PC-Engine LT screen anomaly

[Balusilustalu]

Hi all,

recently my PC-Engine LT started behaving rather strangely. After about 2-10 minutes the video picture goes completely bezerk. I have taken a few photographs to show the problem.

http://www.solarcoaster.eclipse.co.uk/PCE-LT/lt02.jpg

http://www.solarcoaster.eclipse.co.uk/PCE-LT/lt01.jpg

The longer the LT has been switched off, the longer it takes for the problem to occur, with 10 minutes being about the maximum of playing time I am granted. I managed to play through the first two levels of Soldier Blade (the game featured in these photos in case anybody was wondering) from a, shall we say 'cold-boot'. Switching the device quickly off and back on again leaves me with just a few seconds of normal display. The longer I leave the LT switched off, the more playing time I am granted. Because of this I'm wondering if heat accumulation might have something to do with it.
I must point out that eventough the picture goes wonky like this, the game just keeps on running normally, sound plays fine and the game would still be playable if it wasn't for the screwed up image. No matter how long I leave the LT running, the display does not revert back to normal. Because of this I'm wondering if heat accumulation might have something to do with it.
Anyway, I bought the LT from videogameimports.com here in the UK and contacted them once the problem raised it's ugly head (ironically just a few weeks after their 6 month warrenty period had expired). After a few days of waiting they reported back to me that they knew somebody that had encountered the problem before and knew what needed to be done and that they'd get back to me. Time passed... and passed.. and passed. I tried contacting them again and after some weeks I got a reply that wasn't very encouraging. I haven't heard back from them since last summer. I'm hoping anybody here knows something, anything about this matter. ANY info would be helpful, no matter how insignificant, do post. I'd be very thankful. Having such a wonderfull device as an LT rendered virtually useless is painful to say the least. :(

Thanks for your time!

[omnedon]

That's a first in my experience. Lucky you. :/

Could be a loose joint on the ribbon cable connection to the LCD. If the connection is the snap in type (I have no idea). If the membrane is soldered directly to the PCB, it may be hard/impossible to fix.

You need to get in touch with D-Lite on these forums. He is the PCE/Turbo expert.

[rbudrick]

Well it DEFINITELY sounds like a heat problem. Where does a LT vent? is there a fan? You may want to experiment with running a fan on it while you play, possible with the case open to see if it occurs again. I can't imagine something isn't overheating by your desciption.

-Rob

[Balusilustalu]

Omnedon: Hehe... yeah lucky me... :) I've completely disassembled the LT to check for anything obvious. There are several flat plastic ribbons with several traces printed on them that connect the screen to the motherboard. One of them was a bit skewed in the connector. Re-adjusting didn't make any difference unfortunately. I'll see if I can get in contact with D-Lite. Does he frequent these forums or need I look elsewhere?

rbudrick: Yeah.. that's what I was thinking, so I took some drastic measures. I switched on the LT and put it in my fridge for about 10 minutes LOL When I checked back remarkably, the screen was back to normal (was screwed up when I put it in), but alas, it quickly flipped back to rubbish mode. I've been running the LT outside of it's casing and the problem has actually gotten worse. I can't seem to get a clear picture now at all. :(
The PCE LT is passive cooling in it's extreme, with no fans of any kind. There's not even any heat sinks. (Amazing design that motherboard btw).

My next plan of action will be to mod the LT to gain an A/V output and run it on a telly. See if I can get a clear picture that way.

One other thing, when I switch the LT to TV mode the picture appears fine. I say appears because I can't seem to find any channels through the antenna. (This is probably a regional thing with the PCE-GT and TurboGrafx TV tuner adaptors being know for their inability to operate outside of Japan.) All I'm getting is static which makes it a bit difficult to see if the image is screwed up or not. The On Screen Display of the channel numbers that appear for a few secs. when you switch channels is pristine.

The mystery deepens.... :hmm:

[rbudrick]

Hmmm, I'd be willing to bet that the tv mode doesn't use any of the heat sensitive components (processor, etc). The tv tuner part I believe is somewhat seperate from the rest of the system, but I've never taken an LT apart though, so I'm just speculating. . How fast does system go "clear" when you switch to TV mode?

I wonder if theres a way to see what parts are getting the hottest on that board. Is there noticeable heat coming off of any particular area of the board? I wouldn't say to touch the components, as they may be static sensitive and you could risk electric shock, but you might get a general sense of what part may be failing.

-Rob

[chadtower]

There shouldn't be anything on the board he can zap himself with... though those 6V of power from the AA batteries could, you know, graze his little finger. :D

Now, a static electrical shock, yeah that could fry the board, but he can discharge himself easily before doing it. I'd just run it until it starts crapping out and then put my finger on each of the likely components to see if any are hot.