Corrupt graphics on Core Grafx II

[fagin]

Just fired up my Core GFX II today and appear to have corrupt graphics.  Opened the unit up and can't see any obvious trace issues and I reflowed the solder on the RAM chips.

Any advice or guidance?

[turbokon]

Did you tried cleaning the hucard slot?

[fagin]

Graphics are corrupt even with a Super CDROM2 game.  If I swap the engine out with another, everything is fine.

Flashing pixels and vertical lines are quite commonly related to RAM issues afaik, which are the problems I have.

[pulstar]

Do you have an oscilloscope or a logic probe? You'll be able to see if the RAM is at fault quite easily with either of these.

[fagin]

I only have a multimeter I'm afraid.

[pulstar]

If you're based in the UK I could take a look for you or you could just replace the RAM if you can find suitable replacements.

[fagin]

Thanks for the offer (yes I'm in the UK), however I suspect once I'd sent it and paid for return back and your time, I'd be better off buying my own logic tester.  TBH getting hold of replacement RAM chips is probably not that easy either.

[pulstar]

That's the problem with some of these old consoles, sometimes you have to have a faulty unit to take bits off of. Have you tried looking for the RAM online yet?

[fagin]

Ahh good point.  I have a more or less knackered TG so I could use that as a donor if needed.

Nothing of use being returned on-line against those chip references unfortunately.

[pulstar]

Looks like a donor jobbie to ressurrect the great obey

[Fidde_se]

Sometimes when one of the voltage regulators start to give up, yes it's unusual, but it can start to show missing fragments in the graphics (parts of digital static in color), never seen it take over the picture totally but partly, starting when the regulator goes under 4.6V, it could be worth a check.

And while many circuits can run lower then 5v, not much but a little, big parts of it can still be operable, ram circuits usually don't tend to like it.

middle leg ground, the other is in and the other is out, and out should always be 5V (+/- 0.1v max).
(7805)

[fagin]

I grabbed my nuts and took a RAM chip off of a TE and replaced one of the RAM chips on the CGII.  By luck it was the faulty RAM chip and normal service has been resumed.

 

[pulstar]

Glad you got it working

[fagin]

What of the poor TE, though? ) :

It has a mainboard problem that I couldn't resolve...... so it's now relegated to a spares unit.