Graphite Slot loading imac not starting

Question

Hi,
I was given a Graphite imac and told it did not work and did not have a hard drive. I also purchased a second logic board, hard drive, and optical drive. Pressing the front panel power switch causes a small green led near the DIMM slots to light up for less than a second, and I hear a CRT turn on crackle, then nothing more happens. swapping logic boards does not change things. Having a clock battery in or out does not seem to matter. Any suggestions on what I should try next would be appreciated.
Thanks Mark

Answer 1

Hey Mark,
Here's the section on the battery:
"Troubleshooting Logic Board Battery - 14
Logic Board Battery
Important:
Apple highly recommends removing the battery when
handling the logic board. Make sure to use proper ESD protection
when handling modules.
The battery on the logic board controls the stored system settings,
such as date and time. It is only necessary to test the battery when
you can’t power on the computer, or the date and time are reset
every time the AC power is removed.
The battery is also used to power the PMU chip (because the PMU
chip keeps time and must always be running) when the computer
is unplugged from the wall (AC power). The PMU is
very
sensitive
and touching any circuitry that is connected to the PMU can cause
it to crash. If the PMU crashes, the battery life goes from about
five years to about two days if the PMU is not reset. Once the battery
goes dead, the PMU will reset the time and date to 12:00 AM
1/1/04 every time the AC power is removed. To fix this situation,
replace the battery and reset the PMU (refer to “Resetting
the PMU on the Logic Board” mentioned earlier in this chapter).
If the computer has a “No Power” situation, check the battery
before replacing modules. When checking the battery, make sure
the computer is unplugged. Measure the voltage across the battery’s
BT1 positive and ground terminals. The battery should read
3.3 volts to 3.7 volts. If it’s lower than 3.2 volts, replace the
battery and reset the PMU chip."
In my experience they're either over 3.3 volts, completely dead or a few tenths of a volt.
I have seen "PAV" in the discussion forums, does that refer to the small power >supply board coupled to the main logic board, on the same plane?
No that's the "down converter" It takes power from the PAV and converts it to logic board power. The PAV is the big brown board under the CRT. It has all those big parts on it.
What's the CPU speed? Also of the board you subed? How do I check?
If you're looking at the top of the board with the IDE and memory slots at the bottom right underneath there it will say: (eg on a 350 I have here) "part no." here 820-1051-A then "Apple Computer,Inc. ©1999" then a white barcoded label that says at the end 350MHz 64 MB
So this is a 350 that had 64 MB ram originally.
That I asked because depending on the speed the heat sinks will be in different places. This is only a problem if and when you get it booted and only between the 350-400s vs the 600-700s. There's also the issue of the heat transfer pads.
Richard