Graphical glitches on CORE GRAFX II

[Koolhass]

Hello guys!

Lately i'm in a bad luck strike! XD. i have a PC Engine Core Grafx II sitting in home waiting for a SSDS3. I finally got one, only to discover that my console has a problem. I have a original PAC LAND HuCard, and the game works flawlessly. However, other games such a Youkai Douchuuki have minor or heavy graphical glitches, rendering them impossible to play

Also, SSDS3 shows the same errors, and CD games won't even past the "press run" screen

Look how it looks Bonker's



Where i do begin to troubleshoot?

Can be related to CAPS?

Will it work to reflow some IC? (i opened the console, and inside everything seems OK, in the surface at least.)

Thanks!

[ApolloBoy]

I highly doubt it's the caps (short for capacitors BTW), Core Grafx consoles tend to be pretty reliable in that regard unlike the original Duo and the TurboExpress/PCE GT, which have leaky capacitors that can damage the motherboard. It's possible that there's something wrong with the RAM considering it's happening with both HuCards and the SSD3. I'd start by trying to reflow the solder joints on both RAM chips, they're at the very front of the motherboard between the power switch and controller port. If that doesn't work, you'll need to replace one or both chips.

[Koolhass]

I highly doubt it's the caps (short for capacitors BTW), Core Grafx consoles tend to be pretty reliable in that regard unlike the original Duo and the TurboExpress/PCE GT, which have leaky capacitors that can damage the motherboard. It's possible that there's something wrong with the RAM considering it's happening with both HuCards and the SSD3. I'd start by trying to reflow the solder joints on both RAM chips, they're at the very front of the motherboard between the power switch and controller port. If that doesn't work, you'll need to replace one or both chips.

Great!, i'l try that and keep you guys posted. By the way, are ram chips interchangeable between PC engine and Core Grafx ???

[ApolloBoy]

Great!, i'l try that and keep you guys posted. By the way, are ram chips interchangeable between PC engine and Core Grafx ???

They should be, the Core Grafx systems aren't that much different than the white PCE internally and I believe they all use the exact same chips.

[Koolhass]

Well, it seems like I made things worse. I used flux to improve the solder in the padas on the ram and nothing happened, same glitches. I thought it might be a good idea to do something similar on the HU C6270 chip and made things worse, first the glitches got worse, and now i got to the point that the console now only shows a white image.

I killed that IC right? How i could be sure? Anyway, i ordered a console to replace parts, but i have to be sure which component it's faulty.

Cheers!

[kamiboy]

Figuring out exactly which component, or trace on the motherboard, the fault lies with is often possible. But it requires high level knowledge of computer electronics, special equipment, such as a logic analyser, and a circuit diagram of the core grafx 2.

Shotgun replacement of the graphical RAM chips might be your best bet.

[Koolhass]

Here some news. I desoldered both ram and HuC6270. I couldn't find any broken traces or glaring problems, so i solder them back again, and the only thing that i get are scrambled graphics.

Anyway, my replacement PC Engine arrived, to my surprise, it's in better shape than the old one, i can play almost everything, only with one annoying graphic glitch, check it out:







Some games are missing chunks of sprites!

A quick visual inspection, anything looks out of ordinary



Backside, only thing i noticed is this rusted area on the back shield and PCB





Also swapped RAM sticks, but the problem remained the same. Any ideas where to troubleshoot?