Mac IIsi, smily Mac icon comes on and off

Hi
I have two IIsi. When they are powered on, both displays smily Mac icon for few seconds then comes an icon with a question mark.
The problem is that sometimes they work as they should and comes a full desktop mode. But when the full desktop appears it comes on and goes off periodically.
But mostly the booting up process stops at the Mac icon with the quesstion marks in it.
I opened up the case and found out that a few capacitors were leaking.
Could it be the issue related to the symptom?
For example that the Simasi effect on the SE/30 is related to the leaky caps.
Thanks.

Electrolytic capacitors (the "little cans") are used to smooth out power. If they have deteriorated to the point where they are leaking, they cannot be doing their job.
The Samasi effect or "Zebra Stripes" appears on Macs with memory-mapped screens. You are looking directly into memory at the garbage that is there. Dynamic RAM is built from tiny capacitors, and cannot remain stable when there is not enough capacitance nearby to smooth out transient power effects.
Electrolytic capacitors are polarized, and must be installed with + and - facing the same way as the originals. They must be at least the same temperature range, and at least the same capacitance as the ones you replace. Higher temp range and higher capacitance is almost always OK, but may cost a little more and be a little larger in size.
Once you have replaced the failing capacitors, you will need to also replace the 1/2-AA sized PRAM backup battery and reset the PRAM to get the blinking question mark to resolve and stay resolved..

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