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Post by soop on Jun 9, 2018 16:20:00 GMT
I got a GT to try and repair. It has the backlight but no video problem. The soldering looks shit (specifically I think its the wrong kind of solder, its not shiny at all) and it has loads of missing traces. Against the odds it does actually work, I can boot a game and get clear sound, just no video. I looked at the old tread specifically for this issue and tried replacing the specific cap, the 4.7mf one, but no luck. Where's the next place to look? I'll upload a picture so you can see the general area and see if something looks off (I kind of suspect the resistors that seem to have been replaced) Attachments:
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Post by soop on Jun 10, 2018 12:51:24 GMT
Ok, it's actually missing a resistor. I've continuity checked everything (well, all the caps), so I think that might be it.
God knows how I figure out the value tho
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Post by soop on Jun 10, 2018 13:06:47 GMT
Turns out R723 is a zero ohm resistor that triggers copy protection of some kind. Doesn't get my hopes up, but I've jumpered it
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Post by soop on Jun 10, 2018 13:11:33 GMT
Well, that did nothing. On the plus side tho, I haven't made it worse.
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Post by soop on Jun 21, 2018 17:06:00 GMT
Well I replaced the transistor and that did nothing. Any other ideas?
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Post by soop on Jun 23, 2018 17:16:19 GMT
Update, I've checked the voltage off of the pot vr500, and it's too low. It's about 5v, so something between there and the supply must be off. What can I check?
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Post by soop on Jun 24, 2018 12:38:17 GMT
I've taken the shield off the transformer T900, and I'm getting voltages of 7.25 from most of the pins on the inside of the board.
On r515, I'm getting 4.64 volts and on the positive of cc502 I'm getting 6.84.
I understand T900 to be a 24v transformer, so there would seem to be a problem, but I'm unsure where. Could it be the transformer itself?
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Post by spenoza on Jun 24, 2018 14:20:51 GMT
I am sorry nobody has been chiming in. I know fuck-all about this stuff, so I have been staying out of it.
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Post by soop on Jun 24, 2018 15:02:30 GMT
Aww, that's ok. It's quite fun, and I'm learning, but this is useful to document my progress as much as anything!
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Post by soop on Jun 25, 2018 9:05:55 GMT
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Post by soop on Jul 25, 2018 18:50:23 GMT
Dear diary: replaced 901 and 900, but we still have the video problem. I don't even know if there was a next step D: I think I literally have no choice but to mod it with a 3.5" screen
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Post by soop on Oct 17, 2018 16:15:44 GMT
Replaced the screen with a composite 3.5" LCD and it works great. Now the controls are the problem.
So far, I've tested continuity on the pads themselves looks fine. So what else could it be? Everything looks clean.
For some reason, continuity on the pads isn't enough for my dmm to beep.
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Post by soop on Oct 17, 2018 16:38:32 GMT
Checked continuity everywhere, everything is good. It seems like I and II are also linked to directions. I guess it could be a faulty chip? Replaced the capacitor and that did nothing
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Post by soop on Oct 19, 2018 9:19:51 GMT
Balls. Replaced with a working controller PCB and I get the same issue.
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Post by spenoza on Oct 19, 2018 13:31:39 GMT
This is quite a project, eh? Soop's Epic Struggle!
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