REPAIR GUIDE - TurboExpress/PC Engine GT: Video Fix

[nat]

Without going back and reading 5 pages, let me ask.... Did you actually replace the video capacitor? If not, why not? It can look "just fine" and not be.

[thesteve]

yes its a full cap change. (just looked at the pics)
take a close look at C900 (its a ceramic cap on the back of the board, by the transformer)

[farankoshan]

So everything looks fine, doesn't it? This is why it's so damn frustrating.. you guys think it might really be a bad transformer or a bad screen? Or worse, both...?

[thesteve]

id suspect you either had no pic or no backlight, not both

[farankoshan]

I think it's backlight. As my tech-friend was able to deduce from his tests, the transformer may very well have been shorted out. I think it's safe to say that this little TurboExpress is officially...blind. I can use this as a big music player I guess...

[thesteve]

do you have it with you?
join us in chat sometime

[farankoshan]

What do you mean?

do you have it with you?
join us in chat sometime

When and what time? Time zone?

[thesteve]

i am usa west coast, others are east coast, asia and other places.
you will find knowledgeable people on just about any time you look.

[Charlie]

Just out of curiosity, why have you narrowed the problem to the transformer?  What did you do to prove it is not the circuit that "runs" the transformer? 

Charlie

[chop5]

farankoshan you can send the motherboard and slot only in a small necklace box or something to save on shipping. just pack it good in a static free bag. one of us can assemble it with one of our units and be able to service it. just an idea. 

[thesteve]

well said chop.
im sure it can be fixed by one of us, i just was trying to save some shipping costs by trying to walk him through it.

[farankoshan]

This is a pretty good idea actually. I will weigh my options and study packing methods.

You guys have been really helpful so far, and I appreciate it!

[farankoshan]

Just got home and spoke to him:

He made a rough map of what the transformer looks like (hope this shed some light for a solution to present itself):

PRIMARY SIDE                   SECONDARY SIDE
  1 - live                                1 - dead
  2 - power supply                   2 - dead
  3 - live                                3 - dead
  4 - live
  5 - ground

And he assumes that the main power line runs between Primary 2 and Secondary 3. Is this correct?

Does the above make sense to you guys?

Does this guy's video relate to the above?


In the middle of the video, he shows a diagram that seems to look like my problem area. Does this make any sense to you guys? You think that this diagram will help me try again to fix Video on my TGExpress?

[thesteve]

nope
he is showing just the cap fixes

[nat]

Nice how the guy in that video doesn't credit any of the original sources for the fixes.