View Full Version : imsai 8080 CPA question

February 17th, 2006, 09:02 PM
Well the first day with the new imsai was interesting LOL.

But here is my first question :)
On the front and back of the CPA there are some traces that look to have been cut on purpose? Is this normal? on the back side there is some wires and one fried so I need to replace that.
Also fried a chip on the MPU :( . Hope you can buy new replacements for them.
It seems to have sat somewhere damp for the last 15 years so is there anyway to stop this or do you just run and risk it?

Terry Yager
February 17th, 2006, 09:15 PM
It's best to bring it up slowly, using a variac. Start with a low voltage and gradually increase it over a period of a couple-three days. This allows dried-up electrolytic, etc capacitors to re-form, so they are less likely to go *pop* when ya fire it up.


February 18th, 2006, 07:54 AM
Just realized I asked more than one question :)
Thanks for the answer too.

Terry Yager
February 18th, 2006, 09:46 AM
Finding traces cut is not necessarily A Bad Thing. You should be more concerned, and inspect carefully for badly corroded traces, etc, if it has been stored in an unfriendly environment. Can you tell what the fried chip is (was)?


February 18th, 2006, 07:16 PM
On the MPU the fried chip # is DM74367N
I decided to take apart and clean it today and noticed some other odd things.

I have the book that comes with it and was checking the wiring from the PS to the EXP-22 and mine is different then in there? I have no orange wires and the black and white goes to different places on the EXP22 and PS. So I have to believe the computer ran and the manual is useless to me.
The manual says to test the system by plugging in the CPA and giving it power with nothing else in it. When I did that I got a row of lights on the top left all to light up.
The ram card might have a bad capacitor on it not sure but it doesn’t look good part of it is missing.

February 19th, 2006, 08:45 AM
Here is the CPA only in the imsai 8080 running.
Don't see many pictures of them running which I hope to get the whole thing running eventually.