PCEngineFans.com - The PC Engine and TurboGrafx-16 Community Forum
NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: DrunkenMonk on May 26, 2021, 08:29:04 AM
-
So I've got this Turbo Express with a bad backlight circuit (not really a problem, I can figure that out) and was going to swap the screen over on it anyway to a 3.5" (I wired up a composite screen for easier, open air testing, but it also has weird graphical issues that appear to plague gameplay, which makes me figure it's maybe bad ram or a ram trace or via possibly eroded from an old cap, but I don't see anything physically wrong...
Anyway I'm just looking for insight more than anything else due to how the gameplay is affected by the severe graphical issues, I was leaning more toward RAM and I think I can just use the PC Engine schematics since they're roughly the same - but I don't want to waste all of that time if somebody more experienced would say it's the video chip, in which case I'd be able to use a donor from a PC Engine anyway, totally acceptable to me if that's the issue.
Anyway here's some images of what's being output onto the screen:
(https://media.discordapp.net/attachments/670405530837319730/847087078730498068/IMG_20210526_125842.jpg?width=507&height=676)
(https://media.discordapp.net/attachments/670405530837319730/847087079410368512/IMG_20210526_125858.jpg?width=507&height=676)
(https://media.discordapp.net/attachments/670405530837319730/847087080386461706/IMG_20210526_125909.jpg?width=901&height=676)
(https://media.discordapp.net/attachments/670405530837319730/847087081103556688/IMG_20210526_125936.jpg?width=901&height=676)
I actually intend to revert this back to stock since I found a spare screen once I fix this issue, just this really is easier for open air testing anyway, plug the sucker into my bench psu.
If it's actually the ram itself damaged I can check with some donor ram from a PC Engine before ordering replacements, again I just wanna save time by double checking what people may think the issue is more likely to be opposed to getting stuck in a rabbit hole of diagnosis
-
Anything that looks like this I try ram first. If ram isn't the issue, then it's usually a faulty HU6270 but 95% of the time it's ram causing the problem.
-
So interesting! I didn't even think of the HU6270, I did the ole close visual inspection of the chip and notice there's a whole leg just missing??. Low and behold I solder some kynar there and everythings looking absolutely perfect.
It was specifically leg 64, which is fairly close to cc502, which had leaked quite horrendously on this board, so I wonder if during using IPA + old toothbrush it was a little harsh and maybe I've brushed away a weakened leg? Going to be more mindful of that on future ones for sure...
But test was successful, time to undo the LCD mod and stock this puppy!
(https://media.discordapp.net/attachments/670406420323369008/847477696237142016/IMG_20210527_150955.jpg?width=507&height=676)
(https://media.discordapp.net/attachments/670406420323369008/847477697655472160/IMG_20210527_151015.jpg?width=507&height=676)
Thanks for the super helpful fast response, it made me really look closely to the board instead of giving it the know-it-all once over :-\"
-
Congrats on fixing 'er!
-
Glad it was an easy fix.