CoreGrafx II Video issue

[neokellyzero]

I picked up a coregrafx and it has an issue with the video output.  It kind of remind me of when the 72 pin on a NES goes bad:



The audio is fine, and it runs the game with no problem other than the video.  I tried several game and they all were like this.

I hooked it up to a CD Rom attachment and same results





Any suggestions?  Is this fixable or am I going to need a new unit?

[nat]

Wow.

Ummm.... Wow.

I was going to suggest a dirty cartridge slot, as that is usually the culprit for this problem.

Although, that system card screen.... You didn't actually use a System Card, did you? You just used the internal BIOS on the Super CD-ROM^2 attachment, right? That rules out the cartridge slot.

You've got an internal problem. And that's not what I would classify a video problem. The video is outputting just fine. The problem lies in the information the CPU is providing the video circuitry. I'd say you have a CPU problem or a RAM problem of some sort. I'm not sure if it's fixable. We need to narrow down the component causing the problem which appears to be an IC on the logic board itself. Beyond that my expertise ends. Maybe someone else here who has done more internal tinkering can shed a little more light.

[termis]

I'd agree with nat's assessment. 

Have you tried the video output ports on both the CoreGrafx and the CD-ROM interface?  If one of them works, then well, great -- you've found the problem, though I'd be caught off guard if that was really it.

Troubleshooting something like this might be a tough job for the average Joe.  Wishing you best of luck is the best I can do for you. 

[spenoza]

Troubleshooting something like this might be a tough job for the average Joe.  Wishing you best of luck is the best I can do for you. 

We should stick Redifer on it. He's far from average.

[Necromancer]

We should stick Redifer on it. He's far from average.

Oh, yes - he's 'special'. 

[nat]

He's far from average, even special, but I don't know that he knows a lot about the logic board of a CoreGrafx. Although it's true that he never ceases to amaze....

[ceti alpha]

He's far from average, even special, but I don't know that he knows a lot about the logic board of a CoreGrafx. Although it's true that he never ceases to amaze....

...crosses fingers...

I hate to see an NEC console under the weather.

[FM-77]

[ceti alpha]

NEC certainly was ahead of their time in not only electronics, but with the environmental movement as well. I didn't realize the Coregrafx II was recyclable. 

[neokellyzero]

Have you tried the video output ports on both the CoreGrafx and the CD-ROM interface?  If one of them works, then well, great -- you've found the problem, though I'd be caught off guard if that was really it.

Yeah -it does it on both.  I was hoping that someone had run across something like this before-  it sounds like I may be SOL.  I'm pretty handy with a soldering iron, and have done some console mods(with a guide in hand) in the past, so if it were a matter of replacing some components or something along that line I could do it, but as far as figuring out what the issue is I'm clueless.  I hate to shell out for another core-

[nat]

It's the CPU or RAM.

My money is you have bad RAM.

[SNKNostalgia]

Bad Ram is definitely the most likely problem. Also, is the Coregrafx II using the right AC adapter?

[neokellyzero]

I'm using the original pad-105 ac adaptor.  So if it were the ram would I just need to replace the two RAM chips?  I'm guessing that replacements the exact replacements would hard to find, so am I out of luck on this or do you guys think it's worth trying to repair?

[nat]

I've never had to source RAM for these things-- it's not exactly a common problem.

If you (or someone) wants to open up the CG and see what kind of RAM chips it uses I'll see if I have anything on hand that might work. I have a very large supply of computer boards and equipment from the same era as the CoreGrafx, so you never know.

[neokellyzero]

I opened it up and here is a close up of the RAM chips-

http://i166.photobucket.com/albums/u115/neokellyzero/ram.jpg

Any ideas where I can score replacements or can I substitute anything else for them?

Edit: Never mind I think I found a suitable replacement-