HP G62-144DX Refuses to power on

Hi
I have the same model G62-144DX notebook with a similar problem (refuses to power on) although I have no lights whatsoever and was hoping you could help! I'm looking for the RTC battery, so I can remove it and reset the unit, but can't find it. The owner's manual shows it on page 51 under the RAM, but the only thing I see is a small can (appears to be a capacitor) with #
9M3
390
2.5v.
Can you help?
Thanks!

There are 2 service manuals on the page for your model, strange, one says under the bottom cover, the other says remove the main board.
http://h10025.www1.hp.com/ewfrf/wc/manualCategory?cc=us&dlc=en&lang=en&lc=en&product=4150156&task=&

Similar Messages

G62-144DX notebook does not start

Hi,
Out of nowhere, I had a problem with the wireless operation on a G62-144DX notebook w/ Windows 7 HP 64-bit. I noted the wireless indicator light glowing amber (disconnected) instead of blue (connected). In attempting to download the manual from HP (and get the exact model # to diagnose wireless issue) I removed the Battery while the AC power was connected (to read the model # on label under battery) while the notebook was upside down with display open. Since that point I have been unable to turn on the unit. I tried a reset procedure (found online directing to hold power button down for 15 seconds with battery out and AC disconnected) but to no avail. When I press the power button it is normally supposed to light up and the notebook should boot, but it does not. I have verified (with a voltmeter) the AC power adaptor is working and battery is charged and in good condition.
Can someone suggest what I should try next?
Thanks!

Maybe you are looking at the wrong side. My laptop has ram on both sides, one on the underside access by a panel and one on top under the keyboard.
Look here: http://www.notebookparts.com/products/image.php?SECID=&image=http://www.notebookparts.com/images/ful...
It's the yellow circle battery bottom right.

IMac G3 computers still refusing to power up? Here is a solution.

This post is the sequel to the discussion "iMac G3 computers still refusing to power up? Here is what I've found out!", accessible under this link http://discussions.apple.com/thread.jspa?threadID=2326420&tstart=0 .
I made it! I have fixed the issue of the iMac DV refusing to power up.
For this, I had to design and build a prototype of a cost-effective nonresident hardware patch, which I am about to describe in this article. I will also give the instructions of use. Subsequently, I will expose the rationale, which led to the background of the design. Finally, I will report the observations after the experiment with the patch and sketch the theory of its actual operation with the PMU firmware.
*TABLE OF CONTENTS*
1. Applicability condition and restriction
2. Description of the PMU hardware patch
3. Interconnections of the PMU microcontroller with the PMU Hardware Patch
4. Instructions to read before mounting and unmounting the PMU Hardware Patch on the iMac
5. Background to the design of the PMU Hardware Patch
5.1. The genesis
5.2. What the PMU Hardware Patch actually does
6. Recommended updates before using the PMU Hardware Patch
7. User's Manual of the PMU microcontroller
8. Datasheets of the 74HC4049 Hex inverting high-to-low level shifter
9. Datasheets of the 74HC193 Presettable synchronous 4-bit binary up/down counter
10. Errata to the discussion start of February 6th, 2010
h1. 1. Applicability condition and restriction
The hardware patch addresses the issue of a slot-loading iMac, which can be powered up only within two seconds after resetting the PMU microcontroller. It is not required otherwise.
Moreover, it does not need to reside in the iMac, but suffices once to permanently cure the power-management firmware.
h1. 2. Description of the PMU hardware patch
As seen on figures 1 and 2, the PMU hardware patch relies on a low part count: two logic ICs (74HC193 and 74HC4049), two 0805-packaged resistors and two 1206-packaged capacitors, which all fit on a 31mm x 45mm single-sided SMD prototyping board. The circuit consumes a current intensity of about 7.5 milliamps for a supply voltage of 3.3 volts.
The PMU hardware patch functions as a frequency divider of the PMU sub-clock generator output, XCOUT. It applies an active low pulse to the PMU NMI_bar non-maskable input, once every sixteen XCOUT rising edge for half a period. It is disabled when the PMU main clock generator output, XOUT, returns to 0 by oscillations, or when the system is being reset with the PMU RESET_bar input asserted to 0. The peak-to-peak 1.5-Volt oscillations of XCOUT are fed through the 1-nanofarad DC-blocking capacitor to the inverter biased in the linear region by a feedback resistor of twice 270 kilo-ohms, for translation to 3.3V-compatible logic levels.
The power-supply bypass capacitor amounts to 100 nanofarads.
*Figure 1: Schematics of the PMU Hardware Patch*
[Figure 1|http://www.flickr.com/photos/aegidius_2/4923600713/in/photostream/|Click to view in a new tab.]
Note the 0.5mm-diameter insulated copper wires in ochre color on the prototype board (figure 2).
*Figure 2: Picture of the PMU Hardware Patch prototype - component side*
[Figure 2|http://www.flickr.com/photos/aegidius_2/4924196064/in/photostream/|Click to view in a new tab.]
The 10cm-long interface wires can be clamped to the board with cylinder blocks made of epoxy glue (Araldite), as seen on figure 3.
*Figure 3: Picture of the PMU Hardware Patch prototype - interface side*
[Figure 3|http://www.flickr.com/photos/aegidius_2/4924196296/in/photostream/|Click to view in a new tab.]
h1. 3. Interconnections of the PMU microcontroller with the PMU Hardware Patch
The PMU Hardware Patch uses the signals RESET_bar, NMI_bar and the clocks XOUT and XCOUT of the PMU microcontroller, U34 on the Logic Board underside. Both are supplied by the voltage available across the tantalum capacitor C131.
Pin 73 of U34 performs the function INT3_bar because it turns out to be permanently configured as an edge-sensitive interrupt input, once the PMU Hardware Patch has been used. This will be justified in section 5.2. When the computer is plugged to the mains, a pressure on any power button can induce a falling edge on pin 73. U34 responds by asserting pin 75 to logic 0, as long as the computer has to remain powered on from the PAV board.
Pin 10 of U34 is the active low reset input, RESET_bar. It toggles from logic 0 to 1, a few hundred milliseconds after U35 has detected the supply voltage across the capacitor C131 has settled above 2.2 volts, either because a good battery has been inserted in the holder, or else because the computer has been plugged to the mains and the trickle power from the PAV board, T5V, is available. It is also asserted to logic 0, as long as the PMU reset button is depressed.
Pin 9 of U34 is the sub-clock output, XCOUT. The PMU microcontroller selects it for its operation in low-power dissipation mode to carry on the timekeeping, normally as soon as the computer is being shut down. The microcontroller shall then draw no more than 40 microamps typically from the battery.
Pin 11 of U34 is the main clock output, XOUT. It is the default clock of the PMU microcontroller after the reset phase. The microcontroler selects it for its operation in high-speed mode, when the computer is powered on.
Pin 15 of U34 is the active low edge-sensitive non-maskable interrupt, NMI_bar. It is normally unused and its voltage remains pulled up to the microcontroller supply through resistor R124. However, it happens to help resolve the power-up issue when it is controlled by the PMU Hardware Patch. The justifications are exposed in section 5.2.
Figure 4 shows an easier access to the clock and control signal pins of U34, to be connected to the PMU Hardware Patch, from the top of the Logic Board. You will have to solder the PMU Hardware Patch interface wires at the locations pointed to.
*Figure 4: View of the access to the PMU U34 chip signals for the PMU Hardware Patch*
[Figure 4|http://www.flickr.com/photos/aegidius_2/4929783304/in/photostream/|Click to view in a new tab.]
h1. 4. Instructions to read before mounting and unmounting the PMU Hardware Patch on the iMac
All possible updates accessible from the links in section 6 shall be installed. Then remove the battery. All this ensures your iMac will be prepared to interact with the PMU Hardware Patch under the same initial conditions as in the experiment I have carried out.
Afterwards, remove the bottom housing, the metal shield, the SDRAM, the IDE cable and disconnect the hard-drive power cable. Take off the Logic Board together with the Down Converter board and the modem and place it on your workbench. Now carefully solder the PMU Hardware Patch interface wires at the locations pointed to in figure 4. Figure 5 illustrates the result.
Install the boards back in the iMac, reconnect the hard-drive power cable and the IDE cable, and re-insert the SDRAM in its original slot. Put the computer on a large flat and safe area near a power socket. Stand up the PMU Hardware Patch on a plastic pouch, to insulate it for the parts of the Logic Board, as seen in figure 6. Connect the keyboard and the mouse.
Once you have plugged the computer back to the mains, don't take the risk to touch the computer except the keyboard and the mouse, because quite a few visible metal parts are live and lethal by body contact!
Wait for twenty seconds and then unplug the computer from the mains. Wait for a minute. Again, supply the mains to the computer and wait for twenty seconds, before you press the power button on the keyboard. Then let the operating system load until you can see the menu bar. Maybe a window will pop up to warn you that the system date is too ancient, but you can skip it. Now shut down the computer by selecting the command in the Special menu. I know it is awkward to move the mouse pointer when the picture is upside down. But take it easy!
Unplug the computer from the mains and unmount the PMU Hardware Patch. Once you have re-assembled your iMac, you can power it up and use it without the constraint to reset the PMU each time before and then to press on a power button in a hurry within two seconds.
A good tip: get all this task cleanly done by a professional, like a repairman or an electronics technician, if you feel you don't have enough skill in soldering!
*Figure 5: View of the Patch-PMU interconnections*
[Figure 5|http://www.flickr.com/photos/aegidius_2/4929190683/in/photostream/|Click to view in a new tab.]
*Figure 6: View of the mounted PMU Hardware Patch*
[Figure 6|http://www.flickr.com/photos/aegidius_2/4929190963/in/photostream/|Click to view in a new tab.]
h1. 5. Background to the design of the PMU Hardware Patch
h2. 5.1. The genesis
My idea to the design of the PMU Hardware Patch started with the study of the user's manual of the PMU microcontroller and with my observations on the clocks XOUT and XCOUT.
The symptom of the power-up default was accompanied by the disappearance of the clocks XOUT and XCOUT, if no power button was depressed within two seconds after pushing on the PMU reset button. I concluded, it was the reason why the PMU microcontroller could no longer react to a power button signal on pin 73 (P15/D13/INT3) and perform any timekeeping until the next PMU reset.
By looking at the block diagram Figure 1.10.3 (Clock generating circuit) of the microcontroller user's manual, I noticed that any clock oscillator, XOUT and XOUT, can be re-enabled after the CM10 bit has pulsed to logic 1, provided that the SR latch is reset by the NMI_bar non-maskable interrupt line or by the RESET_bar input. If bit CM04 was set to logic 1, then XCOUT resumes the clock oscillations, and likewise for XOUT if bit CM05 was set to logic 1.
I assumed the situation CM04 = 1 and CM05 = 0, as the PMU microcontroller enters the STOP mode. My idea was then to let it avoid the STOP mode and continue operating in the low-power dissipation mode, by periodically refreshing the SR latch reset through a low pulse on the NMI_bar input. Since the 32.768-kHz oscillations on XCOUT fade within a few hundred microseconds, repeating the pulse on NMI_bar at a quicker rate, once every 488 microseconds (i.e. once every sixteen XCOUT clock period) is acceptable.
However, I could not foresee how the non-maskable interrupt routine would interfere with the PMU firmware, whenever the NMI_bar pulse would be acknowledged to let the microcontroller program counter branch to it. I know that events on edge-sensitive interrupt lines are normally latched, which allows the microcontroller state machine to detect them even if they are too short compared to the clock period. And yet, I assumed it differently, after reading this excerpt in the microcontroller user's manual in the section "Precautions for Interrupts": "Signals input to the NMI pin require an “L” level of 1 clock or more, from the operation clock of the CPU". I decided to design and build a PMU Hardware Patch, that would generate a pulse on NMI_bar for a duration of less one XCOUT clock period, actually for half of it. If it is synchronised with the appropriate edge of XCOUT, then maybe the pulse would not cause the branch to the NMI routine. Moreover, when both XOUT and XCOUT are running, the duration of the pulse from the PMU Hardware Patch would exceed the period of the XOUT clock. To avoid the risk that the pulse occurs for more than one period of XOUT, as the operation clock of the microcontroller, I designed the PMU Hardware Patch, so that it remains inactive as long as XOUT is not steadily asserted to logic 1. The PMU Hardware Patch will not either generate any low pulse during the reset phase, as long as RESET_bar is asserted to 0, and as required in the microcontroller user's manual.
Once the PMU Hardware Patch assembled, I took the risk to use it in the iMac DV. What a relief it was, whenever I turned on the computer again, without the need to press the PMU reset button each time. The PMU Hardware Patch works!
After a power cycling of one minute, without unplugging the iMac from the mains, I looked at the time and date I had initially set. The time had not advanced correctly, while the computer was turned off. Instead it was lagging: it recovered with the value I had initially entered, plus about one minute that the operating system takes to load. That means that no clock was running again, while the computer was turned off. Nonetheless I unmounted the PMU Hardware Patch and tried power cycling the computer at any time interval. Powering it on always succeeded without the need anymore to reset the PMU microcontroller before each attempt.
h2. 5.2. What the PMU Hardware Patch actually does
This means the PMU Hardware Patch had definitely interfered with the PMU firmware and cured it with respect to the power-up issue once and for all. I have figured out it interrupts the firmware through the NMI routine, which restores a few data in the non-volatile FLASH memory. These data are used to program the interrupt control register INT3IC, so that pin 73 behaves as the edge sensitive interrupt INT3_bar. This eliminates the need to have any clock running to register a request on pin 73 to power up the computer. Furthermore, when INT3_bar senses a low pulse because a power button is being pushed on, it urges the internal signal "Interrupt request level judgment" to reset the SR latch register, which re-enables any clock oscillator, as seen in figures 1.11.9 (Maskable interrupts priorities (peripheral I/O interrupts)) and 1.10.3 (Clock generating circuit). The PMU microcontroller can resume its operations and look for the source of the interruption. It finds out it has to power up the iMac, because INT3_bar had been latched in as active.
h1. 6. Recommended updates before using the PMU Hardware Patch
+Mac OS 9: Available Updates+
http://support.apple.com/kb/HT1387
+Power PC-based iMac: When to install available updates+
http://support.apple.com/kb/HT2560?viewlocale=enUS&locale=enUS
+iMac: How to Install an iMac Firmware Update+
http://support.apple.com/kb/HT2561
h1. 7. User's Manual of the PMU microcontroller
http://documentation.renesas.com/eng/products/mpumcu/62aeum.pdf
h1. 8. Datasheets of the 74HC4049 Hex inverting high-to-low level shifter
http://www.nxp.com/documents/datasheet/74HC4049CNV.pdf
http://www.st.com/stonline/products/literature/ds/1965/m74hc4049.pdf
http://www.ti.com/lit/gpn/cd74hc4049
http://www.fairchildsemi.com/ds/MM/MM74HC4049.pdf
h1. 9. Datasheets of the 74HC193 Presettable synchronous 4-bit binary up/down counter
http://www.nxp.com/documents/datasheet/74HCHCT193.pdf
http://www.ti.com/lit/gpn/cd74hc193
h1. 10. Errata to the discussion start of February 6th, 2010
1. "PRAM battery": Wrong naming! The Logic-Board battery only serves to support the timekeeping operation when the mains is removed from the computer, whereas the PRAM data are stored in the non-volatile FLASH memory of the PMU microcontroller (in slot-loading iMacs).
2. "(...) sets bit 1 of the CM1 register (system clock control register 1) to 1 (...)". This fragment shall rather read: "(...) sets bit 0 of the CM1 register (system clock control register 1) to 1 (...)".
Aegidius_2
Keep perseverance and reach your goal!

This post is the sequel to the discussion "iMac G3 computers still refusing to power up? Here is what I've found out!", accessible under this link http://discussions.apple.com/thread.jspa?threadID=2326420&tstart=0 .
I made it! I have fixed the issue of the iMac DV refusing to power up.
For this, I had to design and build a prototype of a cost-effective nonresident hardware patch, which I am about to describe in this article. I will also give the instructions of use. Subsequently, I will expose the rationale, which led to the background of the design. Finally, I will report the observations after the experiment with the patch and sketch the theory of its actual operation with the PMU firmware.
*TABLE OF CONTENTS*
1. Applicability condition and restriction
2. Description of the PMU hardware patch
3. Interconnections of the PMU microcontroller with the PMU Hardware Patch
4. Instructions to read before mounting and unmounting the PMU Hardware Patch on the iMac
5. Background to the design of the PMU Hardware Patch
5.1. The genesis
5.2. What the PMU Hardware Patch actually does
6. Recommended updates before using the PMU Hardware Patch
7. User's Manual of the PMU microcontroller
8. Datasheets of the 74HC4049 Hex inverting high-to-low level shifter
9. Datasheets of the 74HC193 Presettable synchronous 4-bit binary up/down counter
10. Errata to the discussion start of February 6th, 2010
h1. 1. Applicability condition and restriction
The hardware patch addresses the issue of a slot-loading iMac, which can be powered up only within two seconds after resetting the PMU microcontroller. It is not required otherwise.
Moreover, it does not need to reside in the iMac, but suffices once to permanently cure the power-management firmware.
h1. 2. Description of the PMU hardware patch
As seen on figures 1 and 2, the PMU hardware patch relies on a low part count: two logic ICs (74HC193 and 74HC4049), two 0805-packaged resistors and two 1206-packaged capacitors, which all fit on a 31mm x 45mm single-sided SMD prototyping board. The circuit consumes a current intensity of about 7.5 milliamps for a supply voltage of 3.3 volts.
The PMU hardware patch functions as a frequency divider of the PMU sub-clock generator output, XCOUT. It applies an active low pulse to the PMU NMI_bar non-maskable input, once every sixteen XCOUT rising edge for half a period. It is disabled when the PMU main clock generator output, XOUT, returns to 0 by oscillations, or when the system is being reset with the PMU RESET_bar input asserted to 0. The peak-to-peak 1.5-Volt oscillations of XCOUT are fed through the 1-nanofarad DC-blocking capacitor to the inverter biased in the linear region by a feedback resistor of twice 270 kilo-ohms, for translation to 3.3V-compatible logic levels.
The power-supply bypass capacitor amounts to 100 nanofarads.
*Figure 1: Schematics of the PMU Hardware Patch*
[Figure 1|http://www.flickr.com/photos/aegidius_2/4923600713/in/photostream/|Click to view in a new tab.]
Note the 0.5mm-diameter insulated copper wires in ochre color on the prototype board (figure 2).
*Figure 2: Picture of the PMU Hardware Patch prototype - component side*
[Figure 2|http://www.flickr.com/photos/aegidius_2/4924196064/in/photostream/|Click to view in a new tab.]
The 10cm-long interface wires can be clamped to the board with cylinder blocks made of epoxy glue (Araldite), as seen on figure 3.
*Figure 3: Picture of the PMU Hardware Patch prototype - interface side*
[Figure 3|http://www.flickr.com/photos/aegidius_2/4924196296/in/photostream/|Click to view in a new tab.]
h1. 3. Interconnections of the PMU microcontroller with the PMU Hardware Patch
The PMU Hardware Patch uses the signals RESET_bar, NMI_bar and the clocks XOUT and XCOUT of the PMU microcontroller, U34 on the Logic Board underside. Both are supplied by the voltage available across the tantalum capacitor C131.
Pin 73 of U34 performs the function INT3_bar because it turns out to be permanently configured as an edge-sensitive interrupt input, once the PMU Hardware Patch has been used. This will be justified in section 5.2. When the computer is plugged to the mains, a pressure on any power button can induce a falling edge on pin 73. U34 responds by asserting pin 75 to logic 0, as long as the computer has to remain powered on from the PAV board.
Pin 10 of U34 is the active low reset input, RESET_bar. It toggles from logic 0 to 1, a few hundred milliseconds after U35 has detected the supply voltage across the capacitor C131 has settled above 2.2 volts, either because a good battery has been inserted in the holder, or else because the computer has been plugged to the mains and the trickle power from the PAV board, T5V, is available. It is also asserted to logic 0, as long as the PMU reset button is depressed.
Pin 9 of U34 is the sub-clock output, XCOUT. The PMU microcontroller selects it for its operation in low-power dissipation mode to carry on the timekeeping, normally as soon as the computer is being shut down. The microcontroller shall then draw no more than 40 microamps typically from the battery.
Pin 11 of U34 is the main clock output, XOUT. It is the default clock of the PMU microcontroller after the reset phase. The microcontroler selects it for its operation in high-speed mode, when the computer is powered on.
Pin 15 of U34 is the active low edge-sensitive non-maskable interrupt, NMI_bar. It is normally unused and its voltage remains pulled up to the microcontroller supply through resistor R124. However, it happens to help resolve the power-up issue when it is controlled by the PMU Hardware Patch. The justifications are exposed in section 5.2.
Figure 4 shows an easier access to the clock and control signal pins of U34, to be connected to the PMU Hardware Patch, from the top of the Logic Board. You will have to solder the PMU Hardware Patch interface wires at the locations pointed to.
*Figure 4: View of the access to the PMU U34 chip signals for the PMU Hardware Patch*
[Figure 4|http://www.flickr.com/photos/aegidius_2/4929783304/in/photostream/|Click to view in a new tab.]
h1. 4. Instructions to read before mounting and unmounting the PMU Hardware Patch on the iMac
All possible updates accessible from the links in section 6 shall be installed. Then remove the battery. All this ensures your iMac will be prepared to interact with the PMU Hardware Patch under the same initial conditions as in the experiment I have carried out.
Afterwards, remove the bottom housing, the metal shield, the SDRAM, the IDE cable and disconnect the hard-drive power cable. Take off the Logic Board together with the Down Converter board and the modem and place it on your workbench. Now carefully solder the PMU Hardware Patch interface wires at the locations pointed to in figure 4. Figure 5 illustrates the result.
Install the boards back in the iMac, reconnect the hard-drive power cable and the IDE cable, and re-insert the SDRAM in its original slot. Put the computer on a large flat and safe area near a power socket. Stand up the PMU Hardware Patch on a plastic pouch, to insulate it for the parts of the Logic Board, as seen in figure 6. Connect the keyboard and the mouse.
Once you have plugged the computer back to the mains, don't take the risk to touch the computer except the keyboard and the mouse, because quite a few visible metal parts are live and lethal by body contact!
Wait for twenty seconds and then unplug the computer from the mains. Wait for a minute. Again, supply the mains to the computer and wait for twenty seconds, before you press the power button on the keyboard. Then let the operating system load until you can see the menu bar. Maybe a window will pop up to warn you that the system date is too ancient, but you can skip it. Now shut down the computer by selecting the command in the Special menu. I know it is awkward to move the mouse pointer when the picture is upside down. But take it easy!
Unplug the computer from the mains and unmount the PMU Hardware Patch. Once you have re-assembled your iMac, you can power it up and use it without the constraint to reset the PMU each time before and then to press on a power button in a hurry within two seconds.
A good tip: get all this task cleanly done by a professional, like a repairman or an electronics technician, if you feel you don't have enough skill in soldering!
*Figure 5: View of the Patch-PMU interconnections*
[Figure 5|http://www.flickr.com/photos/aegidius_2/4929190683/in/photostream/|Click to view in a new tab.]
*Figure 6: View of the mounted PMU Hardware Patch*
[Figure 6|http://www.flickr.com/photos/aegidius_2/4929190963/in/photostream/|Click to view in a new tab.]
h1. 5. Background to the design of the PMU Hardware Patch
h2. 5.1. The genesis
My idea to the design of the PMU Hardware Patch started with the study of the user's manual of the PMU microcontroller and with my observations on the clocks XOUT and XCOUT.
The symptom of the power-up default was accompanied by the disappearance of the clocks XOUT and XCOUT, if no power button was depressed within two seconds after pushing on the PMU reset button. I concluded, it was the reason why the PMU microcontroller could no longer react to a power button signal on pin 73 (P15/D13/INT3) and perform any timekeeping until the next PMU reset.
By looking at the block diagram Figure 1.10.3 (Clock generating circuit) of the microcontroller user's manual, I noticed that any clock oscillator, XOUT and XOUT, can be re-enabled after the CM10 bit has pulsed to logic 1, provided that the SR latch is reset by the NMI_bar non-maskable interrupt line or by the RESET_bar input. If bit CM04 was set to logic 1, then XCOUT resumes the clock oscillations, and likewise for XOUT if bit CM05 was set to logic 1.
I assumed the situation CM04 = 1 and CM05 = 0, as the PMU microcontroller enters the STOP mode. My idea was then to let it avoid the STOP mode and continue operating in the low-power dissipation mode, by periodically refreshing the SR latch reset through a low pulse on the NMI_bar input. Since the 32.768-kHz oscillations on XCOUT fade within a few hundred microseconds, repeating the pulse on NMI_bar at a quicker rate, once every 488 microseconds (i.e. once every sixteen XCOUT clock period) is acceptable.
However, I could not foresee how the non-maskable interrupt routine would interfere with the PMU firmware, whenever the NMI_bar pulse would be acknowledged to let the microcontroller program counter branch to it. I know that events on edge-sensitive interrupt lines are normally latched, which allows the microcontroller state machine to detect them even if they are too short compared to the clock period. And yet, I assumed it differently, after reading this excerpt in the microcontroller user's manual in the section "Precautions for Interrupts": "Signals input to the NMI pin require an “L” level of 1 clock or more, from the operation clock of the CPU". I decided to design and build a PMU Hardware Patch, that would generate a pulse on NMI_bar for a duration of less one XCOUT clock period, actually for half of it. If it is synchronised with the appropriate edge of XCOUT, then maybe the pulse would not cause the branch to the NMI routine. Moreover, when both XOUT and XCOUT are running, the duration of the pulse from the PMU Hardware Patch would exceed the period of the XOUT clock. To avoid the risk that the pulse occurs for more than one period of XOUT, as the operation clock of the microcontroller, I designed the PMU Hardware Patch, so that it remains inactive as long as XOUT is not steadily asserted to logic 1. The PMU Hardware Patch will not either generate any low pulse during the reset phase, as long as RESET_bar is asserted to 0, and as required in the microcontroller user's manual.
Once the PMU Hardware Patch assembled, I took the risk to use it in the iMac DV. What a relief it was, whenever I turned on the computer again, without the need to press the PMU reset button each time. The PMU Hardware Patch works!
After a power cycling of one minute, without unplugging the iMac from the mains, I looked at the time and date I had initially set. The time had not advanced correctly, while the computer was turned off. Instead it was lagging: it recovered with the value I had initially entered, plus about one minute that the operating system takes to load. That means that no clock was running again, while the computer was turned off. Nonetheless I unmounted the PMU Hardware Patch and tried power cycling the computer at any time interval. Powering it on always succeeded without the need anymore to reset the PMU microcontroller before each attempt.
h2. 5.2. What the PMU Hardware Patch actually does
This means the PMU Hardware Patch had definitely interfered with the PMU firmware and cured it with respect to the power-up issue once and for all. I have figured out it interrupts the firmware through the NMI routine, which restores a few data in the non-volatile FLASH memory. These data are used to program the interrupt control register INT3IC, so that pin 73 behaves as the edge sensitive interrupt INT3_bar. This eliminates the need to have any clock running to register a request on pin 73 to power up the computer. Furthermore, when INT3_bar senses a low pulse because a power button is being pushed on, it urges the internal signal "Interrupt request level judgment" to reset the SR latch register, which re-enables any clock oscillator, as seen in figures 1.11.9 (Maskable interrupts priorities (peripheral I/O interrupts)) and 1.10.3 (Clock generating circuit). The PMU microcontroller can resume its operations and look for the source of the interruption. It finds out it has to power up the iMac, because INT3_bar had been latched in as active.
h1. 6. Recommended updates before using the PMU Hardware Patch
+Mac OS 9: Available Updates+
http://support.apple.com/kb/HT1387
+Power PC-based iMac: When to install available updates+
http://support.apple.com/kb/HT2560?viewlocale=enUS&locale=enUS
+iMac: How to Install an iMac Firmware Update+
http://support.apple.com/kb/HT2561
h1. 7. User's Manual of the PMU microcontroller
http://documentation.renesas.com/eng/products/mpumcu/62aeum.pdf
h1. 8. Datasheets of the 74HC4049 Hex inverting high-to-low level shifter
http://www.nxp.com/documents/datasheet/74HC4049CNV.pdf
http://www.st.com/stonline/products/literature/ds/1965/m74hc4049.pdf
http://www.ti.com/lit/gpn/cd74hc4049
http://www.fairchildsemi.com/ds/MM/MM74HC4049.pdf
h1. 9. Datasheets of the 74HC193 Presettable synchronous 4-bit binary up/down counter
http://www.nxp.com/documents/datasheet/74HCHCT193.pdf
http://www.ti.com/lit/gpn/cd74hc193
h1. 10. Errata to the discussion start of February 6th, 2010
1. "PRAM battery": Wrong naming! The Logic-Board battery only serves to support the timekeeping operation when the mains is removed from the computer, whereas the PRAM data are stored in the non-volatile FLASH memory of the PMU microcontroller (in slot-loading iMacs).
2. "(...) sets bit 1 of the CM1 register (system clock control register 1) to 1 (...)". This fragment shall rather read: "(...) sets bit 0 of the CM1 register (system clock control register 1) to 1 (...)".
Aegidius_2
Keep perseverance and reach your goal!

Macbook Pro (Mid 2012 Version) refuses to power on

Hello Everybody
I have some problem here and I was hoping for some help!
Problem: Macbook Pro refuses to power on. ( no fan sound, no hard disk spinning sound)
Event leading up to problem: I was using the laptop when it suddenly it just blanked out( Power went off ). I pressed the power button and the computer started; however, after loading the operating system ( I managed to log in to the OS and was navigating my desktop), the computer blanked out again. Ever since then, the Macbook Pro refused to power on.
Solutions I have tried:
Plug in a new Magsafe Charger : I plugged in a new macbook pro charger which is working ( i verified that its working by plugging it into another macbook). The charging indicator refused to light up even when the working charger is plugged into the macbook pro.
Tried a SMC reset : I tried a SMC reset by pressing left control, left option, left shift and power button and releasing it all together. Nothing changed.
Final Note:
My macbook is out of warranty already so I am prepared to open up the laptop to disconnect and reconnect the battery, or do anything you guys might suggest;
that said, please do not advise me to bring this into a service centre. That will obviously be my final resort. We wouldn't be talking here if we could just bring it to the service centre right?
Thanks for all the help that i might receive guys !

When did it happen? After updating/upgrading? or just randomly?
You can try to perform a SMC reset and resetting the PRAM:
SMC Reset -> http://support.apple.com/kb/HT3964
PRAM/NVRAM -> http://support.apple.com/kb/ht1379

My Lumia 920 frequently refuse to power on

I have had d phone for up to 12 months. Although a good phone, I experience frequent refusal to power on. This requires taking it to Nokia care almost on monthly basis. I use only Nokia chargers, & don't allow the battery to drain b4 charging. What can I do.

Looks like a hardware issue, unfortunately. It is surprising that Nokia Care wasn't able to help, but i would be looking at a faulty battery, or battery connector.

My Hp notebook laptop refuse to power-on

I travelled for 4 months and left my hp notebook laptop for dat period witout using it with d battery intact but on arrival i decided to use it and it refuse to power-on.I tot mayb d ba3 is down so i charged for more long hours but still it didnt on den someone told me dat bcos i left d ba3 in it for dat long period dat it has damaged d motherboard.Is it true? Wot can i do? Cos d person advice me to get anoda laptop but d laptop is new i avnt used it for long

remove the battery
remove the AC adapter
hold down the power button 30 seconds
wait 30 seconds
plug in AC adapter, not battery
try to turn it on

Upgrading CPU on G62-144dx Notebook

I am looking to upgrade the processor on my G62-144dx Notebook, Product WA91UA#ABA. I currently have the factory-installed i3 2.13 GHz processor. I have looked at the manual and noticed that the compatible processors with the speeds that I require -- 2.66 GHz and above, to run Sonar X1 Studio software -- are noted for "model 1.1 only." How can I tell if I have model 1.1?
If I do not have the correct model ("1.1"), would one of the "model 1.1"-specific processors still be functional on this computer, albeit with less than optimal performance, or is there another issue (like physically not fitting the motherboard) that prevents such an installation?
Thanks, trying to decide whether or not to keep this computer or to get a custom-made elsewhere.

Hi,
Your machine currently has:
2.3GHz/1.4GHz VISION A6 Technology from AMD with AMD Quad-Core A6-3400M Accelerated Processor
Source: http://support.hp.com/us-en/product/HP-Pavilion-dv7-Entertainment-Notebook-PC-series/5145684/model/5...
From 2.3GHz to 2.4GHz you won't gain anything. But if you wish, you can try 35W processors listed on page #1 of the following document:
http://h10032.www1.hp.com/ctg/Manual/c03043778.pdf
Note: You can't overclock many branded machines. Vendors lock them in BIOS. One understanding reason: they don't want customers overclock machines then after one or two months cunstomers send machines back due to overheat.
Regards.
BH
**Click the KUDOS thumb up on the left to say 'Thanks'**
Make it easier for other people to find solutions by marking a Reply 'Accept as Solution' if it solves your problem.

Zombie iMac 21.5": refuses to power on for hours

This has happened twice to my 21.5" iMac (mid-range): After writing to disk for hours, I power down the iMac in the evening via Apple menu, disconnect the cables, carry it to another room, connect the power cable, but the iMac refuses to power on.
Measures: verified cable connections, electrical power outlet, reset SMC. Result: iMac refuses to power on.
Solution: disconnect all cables, wait till morning, connect power cable, press power button. Result: No issues, works fine.
Any idea why this happens? Have you experienced this?

Hi, just to share I experience the same thing.
One month ago this happen to me when I power off the socket power (the power to the plug of my iMac 27"). When I power on the socket power and press the power button behind the screen, no respond at all. Tried various method suggested at support site but no improvement. Finally I gave up go to bed and next morning it power up perfectly fine.
After this I use iMac for a month without power down the main socket it work perfectly fine whenever I power up or power down using the push button behind the screen. Just 15 mins before this post, I came back home, the iMac still cool as it not been turn on. I power off the main socket, remove the power plug, put back the power plug again, turn on the main socket power, press the power button behind the screen, no respond at all. Sign......do I need to wait till next morning then can power up again? Sign............
What shall I do?
Do I have to restrict myself do not power down the main socket power so that I can use the iMac as and when I like.
Shall I send for Servicing?
Somebody please help.

My first generation iPhone just refuses to power up. What can I do?

This morning my iphone was fully charged and working fine. I may have mistakenly connected a power cable to it that went nowhere. When I got where I was going a bit later, it refused to power up at all. I have reconnected to the charger, and after an hour, still no signs of life. Any fixes or ideas. It was not dropped, immersed or abused in any way.
thanks.

Bring it into an Apple Store for a free diagnosis and quote for cost of repair/replacement of parts.
If the costs are $500 or over, consider using the money toward a new or "newer" (used) Mac.

G62 144dx key replacement

My left arrow on my G62 144DX black keyboard came off. Looks in good shape but cannot get it to click back on. Any suggestions?

Here is the Service Manual, which you will need:
Manual
This is your board I believe:
GL40 UMA system board with HDMI card reader (for models 1.1 and 1.2 only) 605140-001
It is pretty reasonable on eBay:
http://www.ebay.com/itm/HP-COMPAQ-G42-G62-INTEL-MOTHERBOARD-605140-001-TESTED-WORKING-/271483646585?...
If this is "the Answer" please click "Accept as Solution" to help others find it.

My ipad 2 is frozen, the email system was not working so i tried to turn it off and start again but it has refused to power down

My Ipad 2 mail system was not working so i tried to power down to restart again but it has refused to power down and it also refuses to come on. i have held the power button for over a minute but there is no response.

Have you tried basics from the manual?
Restart 0- you tried.
Reset?
Restore?
iPad 2 User Guide (For iOS 4.3 Software)

IbookG4 refuses to power up

brand new i book will not power up and does not respond to pram proceedure.subsequent attempts yeild a fan sound followed by the start up audio and no start up. Is this a lemon?

Did it refuse to start right out of the box? If so you may have a "DOA" machine. If it started earlier what have you installed since it stopped starting (ram, software, peripherals)
Try starting from the CD disk one by holding down the "C" key and run the disk utility to try and repair the disk.
Have you upgraded ram?
Try removing the additional stick and start up.

Out of the blue, my computer stops working and refuses to power up. Can anyone help?

So I am posting this on a Thursday night. Monday morning and night, my computer was working fine. Come Tuesday, however, and my computer won't turn on. I don't think much of it; I shrug it off and head to school. Come back from school, and the computer still does not turn on.
Now I get worried. So I:
1,) I make sure the cords are all secure and plugged in, which they were. The computer is plugged directly into the wall; it is not on a power strip. The green LED lights up when i reconnect thew power cord after disconnecting it. But, after I hit the power button, the computer flickers and the light turns off.
2.) I swap out the power cord on my computer eith the one for the monitor. Still no luck.
3.) My friends told me it just might be dust. So I removed the shell, and used a can of compressed air. MUCH dust came out. I put everything back together, and still the computer does not work; the same thing occurs as was before.
4.) Now I go through a much deeper cleaning, removing fans and cleaning it all by hand, still to no avail.
I have tried everything I know to fix this thing. Know I am reaching out to the community. Anyone have any advice/suggestions? Has anyone also run into this problem? I own and mainly use an HP Slimline s5310y. This is the computer that broke. It's a 64-but computer running the Windows 7 (64-Bit) OS. Any help at all would be greatly appreciated!

Hi,
Try this procedure and see if you can isolate the issue. Trouble Shooting Power Supply Issues. Don’t skip any steps.
HP DV9700, t9300, Nvidia 8600, 4GB, Crucial C300 128GB SSD
HP Photosmart Premium C309G, HP Photosmart 6520
HP Touchpad, HP Chromebook 11
Custom i7-4770k,Z-87, 8GB, Vertex 3 SSD, Samsung EVO SSD, Corsair HX650,GTX 760
Custom i7-4790k,Z-97, 16GB, Vertex 3 SSD, Plextor M.2 SSD, Samsung EVO SSD, Corsair HX650, GTX 660TI
Windows 7/8 UEFI/Legacy mode, MBR/GPT

Have a PB 540c that refuses to power up now

Could it be the power adaptor that needs replacing?
Sadly, the batteries were were allowed to drain before this happened
Thanks for any help.
Stala
G3 PB Pismo , PB 540c (Mac OS 8.1) and PB 190

Stala
Welcome to the Discussions.
How long was it since the PB was last used? Had the batteries (it sounds as if you had two of them) remained in the PB since last use? Was the AC adapter attached and powered-on the while? If not, have you left the adapter attached and powered on since attempting to start up?
Problems arise when the internal backup battery depletes during storage. The PB then has no way of knowing what startup device to use, where that is and (very probably) which day of the week it is because the settings in PRAM have evaporated or been scrambled. If your batteries are originals, their internal EEPROMs (which are supposed to keep the batteries 'smart') will also have lost their settings. Take the batteries out and disconnect the AC adapter if that has been atached. Let the PB stand for 20min or so.
Then press, and hold for 20sec or so, the keys control-option-command-power (the left-pointing triangle). This is to reset the Power Manager. The PB 500 series has no dedicated reset or interrupt switches. Reconnect the AC adapter, wait five minutes, and then attempt to start up. Repeat, if this is unsuccessful, a couple of times. If you still get no joy, leave the AC adapter attached for a couple of days, with the main batteries inserted, and then try again.
This article and the repair manual may be of use to you, but your starting point has also the disadvantage that the batteries are already out of the race. That is, you may have to do some coaxing of the main batteries to be able to get the backup battery also to take some charge. (Only if the AC adapter does not become warm to the touch during attempted recharge of the main batteries need you suspect the adapter of malfunction.)
Do you have install floppy disks, and the Disk Tools, for the PB?
Apple IIe; 68K: 11DT + 4PB; PPC: 5DT + 3PB; G3: 6DT System 6.0.8 to OS 10.4.x

MX922 is refusing to power off, connect to network. How to move back to USB?

My MX922 is being a royal pain in the butt. It's only a couple of months old, but it's the first Canon printer I've had in a decade that hasn't been great from the start.
It takes forever to shutdown (more than a day right now).
how can I reset it to the factory defaults? I'd rather shut off the wireless support completely (since it doesn't work worth a darn) and just use USB, but I dont' see how to do that.
Thanks
Scott

Sometimes wireless signals can interfere with the printer (especially connected wirelessly). Try powering off your router and power cycling the printer (unplug if need be). Turn printer back on with the router still turned off. Then, you should be able to reset the settings on the printer. On the printer, press Menu > Device Settings > Reset Setting > Reset All. Should be fine from here to power back on your router. Then, you can just connect the cable to your PC and should be able to print.

HP G62-144DX Refuses to power on

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