REPAIR GUIDE - TurboExpress/PC Engine GT: Video Fix

[fagin]

Any pointers on how to resolve this low voltage issue? 

[thesteve]

First unplug the screen and recheck (keith had a shorted screen)
The video cap fixes all relate to that voltage
The pot near the side of the unit adjusts the -24V supply, the one near the top adjusts the +5V

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[fagin]

First unplug the screen and recheck (keith had a shorted screen)

Around 11.6v with the screen unplugged.

[thesteve]

That's low
Check the large 22uf cap and the 4.7s


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[fagin]

By tweaking VR500 I can just about get to 14v.

Apologies, not sure what you mean by "check". 

All caps have been replaced and it's the same problem I had prior to the cap replacement.

[thesteve]

I was vague because I want you to test the caps and check their connections
Also inspect the board around them


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[cam]

You should fix this problem following this tutorial (in french) :

http://blog.home108.com

Best regards,

[fagin]

Thanks for that link..... where are the screens available from?

[thesteve]

If you need an original screen, anyone doing screen swaps should have a pile of good ones

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[fagin]

It's not an OE screen I need.  Something is obviously mullered with my main board, even after looking at the areas you suggested, I didn't get anywhere. 

[thesteve]

screen swaps can be done, with a composite mod

ebay sells screens, some work some dont

[coryoon]

Hi,

I have a GT with the 'screen on but no picture' issue - screen is black (but lit), sound works etc.

Is there anyone in the UK that does the Cap replacement?

Thanks.

[Rosser]

deleted post

[Moudamir]

Hello everyone,

So I follow the replacement process for the capacitors, mine was showing no video and no audio. Video only backlight sometimes shadows !!! And audio was low.
I've changed the audio circuit !!! And it's perfect. And I've changed the video one it came back for 10 sec and that's it !!! Don't know what to do !!!
I've changed total 10 capacitor out of 18 still nothing. Didn't go under the shield yet...
Any ideas ?

[Keith Courage]

Remove the shield and change the rest before looking at any other options for the problem. That way you can at least rule out the capacitors if the problem still exists.