PC-88VA v1-v3 LED Error

[RobIvy64]

Howdy!

Not necessarily PC-98 related, but close enough.

I picked up a couple of PC-88VA computers from a member here. They have LEDs on the front that show which video mode you are using; V1 V2 V3.

The computers power on, but all 3 LEDs illuminate and there is no video or audio. Someone attempted to replace the original 3.6V Ni-Cad battery with an incorrect CR2032 which I have removed and replaced with a new correct battery. I have also disassembled and cleaned one of the machines, reseating all of the socketed ICs.

I see these computers sell on YJ all the time with the same exact error, but I can't find any definitive information on what it means or what to check. Any ideas?

[RobIvy64]

This is the only imformation I can find

http://hanihanisayoko.seesaa.net/category/21726830-1.html

https://sites.google.com/site/allabout88va/home/repair/checkpoint

[98digger]

I don't really know much about the PC-88, but I believe that replacing the capacitors might be the best option for you at the moment. That way, any potential issues that the caps could cause or are causing can be eliminated.

Are there any EPROM on the motherboard? If the PC-88 is failing to initialize into a single video mode, then chances are the components that control it (BIOS EPROM/N88-BASIC ROM/VDC) are acting up.

There is a chance that a certain component in the PC-88VA is defective and prone to failure due to some sort of design flaw. Recall how early VIC-II in the first Commodore 64 revisions failed due to a flaw that would make "snow" appear on the screen and cause sprites collision detection to fail. Similarly, these PC-88VA, if they are mostly being sold as "not-working" on Yahoo Auctions, probably all suffer from a design flaw, but if people are still buying them, then they must be relatively easy to fix. Maybe all you need to do swap out the VDC.

And then, of course, it is important to note that broken PC-9801 on Yahoo Auctions are sometimes purchased with the intent of using the case with a modern motherboard. There is the possibility that people are doing the same with broken PC-88VA; scrapping the original hardware and salvaging the case.

Anyways, I'll be on the lookout for any information about the issue you are having. Hopefully it is something simple that can be resolved relatively easily.


-98digger

[RobIvy64]

Most of the caps are tantalum and are on the floppy controller PCB, so i'm skeptical that is the issue, however I can't rule it out because I have repaired many NEC electronics over the years just by changing the caps.

[Tw3ek]

I posted a question to the writer of the first blog about your issue, as he seems knowledgeable regarding PC-88VA models! I will let you know when/if he replies.

[Tw3ek]

For anyone else interested, the answer given to me was that the cause of this error is the leaking of the secondary battery inside the PC-88VA. 

Robivy, are the traces around that battery damaged at all, or is the battery even present?