Pc Engine LT/Screen Repair

[wolfman]

Hello,

I am new to this forum. I already had a good look around, there is quite some info here fortunately 

Recently I acquired an LT, which has a non-working Screen. Backlight seems to work though. Since I did not find any info, I am asking here for help.

Is this connected perhaps to a damaged video processor?
Or is the caps? Which ones could that be?
Or is it related to the mainboard?
Are there any replacement screens that would fit? Where could I obtain them?
Does anybody here have some experience with fixing an LT?

I would be happy for any useful input.

Many thanks,
Wolf

[BlueBMW]

Replace all the mainboard caps first.  Ill bet that once you do the screen will come back to life.  Ive had a few LTs do that.

[wolfman]

Thanks for the hint, hope you´re right!

Do you know what screen would be a good alternative, if this won´t help it?

[BlueBMW]

Turbokon has done screen swaps on express systems.  You might consult him on that.

[GohanX]

I turned mine on due the first time in over a year yesterday and got the same thing, backlight was on but nothing on the screen. After a few minutes the caps warmed up and the screen came to life. I ordered some caps, hopefully there's no damage from leakage.

[wolfman]

Hey, thats interesting. I also have a TE that takes a few seconds until you actually see the screen. Sound is also weak, so maybe thats really a cap-related issue. Will have a look at this.

What if its not cap-related? What else could it be? Videoprocessor?

[wolfman]

Is there some sort of documentation of the LT somwhere on the web available, like it is for the TG?

[BlueBMW]

I dont think we have a service manual or anything like that for it.  There should be a cap chart somewhere though.

I really doubt its a video hardware failure.  I would bet money its the capacitors.

[wolfman]

I dont think we have a service manual or anything like that for it.  There should be a cap chart somewhere though.

Oh, thats sad. I hope it will surface some day....

[wolfman]

I have been working on the unit today, and found 3 caps that had been soldered by the previous owner very very badly, looks like they didn´t hold longer than 10 minutes. Unfortunately a few lines already had come of the board, loosening the caps.

Can someone help me find their destination? Since there had been some brutal soldering I am not sure where the original leads ran to...at least I have to guess, which isnt too good. If I would find another spot I could solder a cable to one leg, and put the end where to contact was supposed to be.

The caps concerned are on the left side of the LT main board, around the 9V DC power jack/loudspeaker connector.

I have attached a few pics. You can see the missing lines, I am not sure about where they originally were attached to.

Is there someone who knows that or has good photos where you could see it, and could possibly trace the original route on the board (for maybe a 2nd solution)? That would be awesome.

http://www.flickr.com/photos/65709578@N06/12058745826/#
http://www.flickr.com/photos/65709578@N06/12057881735/#

Any help on this is greatly appreciated!

[turbokon]

Hold the board up against a light source like a lamp. You should be able to see the trace.


Sent from my iPhone using Tapatalk

[thesteve]

Looks like you found the traces (correct arrows on pics)
Have seen a bad diode cause no pic, but caps most often

Sent from my ADR6300 using Tapatalk 2

[wolfman]

Yes, but where do the traces END, thats what I want to knkow. Anyone?

[Keith Courage]

The easiest solution is to scrape off the green to expose some contact to solder to.

[wolfman]

Look, I want to know at which part the trace ENDS. I know that I can scrape the green off...