PC Engine GT Not loading games - Green/Turquoise screen.

[phipscube]

I'm not having much luck just lately with the GT. MY own has just bit the dust. I've had it 5 years now. Recapped at the time I bought it and soon after I region modded it with the first revision of the Obey chip from BlueBMW. Its been awesome. apart from one thing, it has 3 dead/stuck pixels. I got a homebrew program off someone on here years ago too that would strobe many flashing block colours in an attempt to unstick at least some of the pixels.

Well, a few months ago I finally plumped for a Turbo Everdrive v2.4. Its been great, finally able to play all sorts of super expensive games (like Coryoon) without selling a lung. I now decided to try out the pixel fixing program. I started it up and left it running. My idea was to leave it a few hours then turn it off. Problem is I forgot about it and went to bed.

Next morning I woke up and saw my GT powered on but dead.... I suddenly realised I'd left it on all night. Not such a big deal.... if you don't use Eneloop batteries. I have heared that when they start to die they can cause problems with the obey chip and possibly other things inside the GT as they drop off very quickly. Normally when I'm playing and the screen starts to go white I instantly turn off. Alas.

I found some fresh Eneloops, swapped them out and checked.... it still worked... phew!

But then when I got home form work I turned the GT on to play something and it initially loaded the Turbo Everdrive menu... with slightly corrupt GFX. I turned it off, then on again.... white screen.... tried multiple times.. same problem. tried real games.. same.

I thought maybe I had damaged the obey chip so decided to take out the mod and solder back in all the cart pins etc. still the same problem.

I notice that when I turn the brightness right down the screen has a Green/Turquiose shade to it. Right up its white. The actual brightness itself doesn't seem to increase or decrease, it just changes colour. Its like this with or without a game inserted.

I've checked continuity on the flex cable from the cart board to the main board and all seems to buzz out ok. The pins inside the card connector look ok (although I can't be 100% sure. I hear that TEDs can cause problems in there by flexing the pins too much, if they are flexed too much then they are all evenly flexed) I'm wondering if something is more seriously wrong with it like one of the 62xx chips..

Any advice to narrow this down would be very appreciated

[Xtrasmiley]

Sadly I can't help man, but since you say you tried real games, maybe a new cap kit is in order or a different power supply first? If batteries result in the problem, have you tried an ac kit? I found one on Amazon that is only $10 that works great if you need the link.

[Keith Courage]

Sounds like a region mod issue or that the cart pins got damaged from the turbo everdrive. Shine a flashlight in the cart slot to see if any of the pins are bent. Also, double check the soldering you did when putting the system back to normal minus the region mod.

With bad caps you wouldn't be able to change the brightness.

[phipscube]

Hi, sorry for the delay. I've been away. I've not tried a PSU to be honest. But its always been fine with batts. I tried looking into the cart port with a torch, all pins look fine (If they are bent then its evenly bent, but they protrude nicely). Is there a way to flex them back a little to be sure?

All soldering is fine too, I checked with a multimeter. It was a problem even before I took out the Obey chip. I think I will try and order a new cap kit to see if that helps but I have a bad feeling it's one of the Main chips because even without a cart in the screen behaves differently with its colour, normally the screen would just be white and go brighter and darker with no game in, not from a shade of white to a shade of green with no brightness increase. Its exactly the same with a cart in too. Now and then I get a high pitched tone coming out the speaker too when I turn it on.

Just out of curiosity, does anyone know if the 62xx chips in a regular white PC Engine can be transplanted to a Turbo Express/PC Engine GT? if it does end up being that, I could maybe buy a working cosmetically beat up PC Engine on Ebay for real cheap and swap out the chips...

[Keith Courage]

Yes, the chips are interchangeable.

[phipscube]

OK great I have found a small tool at work that might enable me to reach into the cart port and gently flex the pins. If that doesn't work I'll replace the caps to see if by chance it's one of them. And if that doesn't work I'll try to get a pce to transplant the chips over.

[Keith Courage]

I have had to change a few 6820 chips in these so that might be the problem. However, in most of those cases the symptom was a white screen. Not green

[phipscube]

The screen is white when the brightness is at the normal level, its only green when I turn it right down. I have heared that using rechargeables is bad for the GT especially letting them run completely out whilst power is still on. I did that by accident when I left it running all night. So I feared the worst. Just strange it worked ok in the morning after I checked then by the evening it was dead.