new to repairing: malfunctioning console system

I'd start by looking carefully for solder bridges and drips, a little scrap of wire you may have dropped, a thin trace that got scraped, etc. I've never seen inside a PC Engine so I'm not sure what's most likely.

James,

Thanks a lot for your avices. Here's a link to show you the mod I did:

Don't consider the pink wire, because in the end I routed that signal from a different pin.

As you can see almost al the soldering is done in the bottom of the expansion bus.

How do I normally check if a chip is malfunctioning? I fear that some static elecrticity may have damaged the video memory.

If it's needed I think I can take a picture of my own modded board and post it somewhere.

Thanks a lot for th help you may give me.

Mauro_

Unfortunately it's very difficult to check some IC's, particularly memory unless someone has written diagnostic software that will run on the system in question. Are there any socketed IC's on the top of the board? I would still lean towards something getting mechanically disturbed in the process. Are you *very* sure none of the expansion bus pins are shorted together? The memory and everything else likely resides on that same bus so a line that's stuck low or high can cause all sorts of weirdness.

James,

Unfortunately there's no socketed IC on the board. Though, I'm quite confident that no pin is shorted with others. I'll post a closeup picture of my mod later, so you can take a look at it.

I really wish it was something mechanical! Do you think a memory chip caould be damaged by a temporary short circuit? I fear so...

Also, what makes me think that some chip is damaged, is that the standard analog (RF) video output has the same problem as the newly modded RGB output. Since the RF video output seems to be routed

*before* the mod I made, the problem must be even before the RF circuit. That's why I fear that the memory is damaged.

If you still have some time for giving me more advices I'd really appreciate it and I will not dispose of the console as I wanted to.

Expect the pic of the board later today.

Thanks again, Mauro_

I've uploaded a few images of the mod. I hope they can be useful, or at least interesting to look for.

If it's just a fixable mechanical problem I'd be very happy! :-)

Here we go:

This is an overview of the board from the top side. You can see the video chip (Hudson HuC6260), the RF analog output on the lower left zone (the big metal plate) and the ribbon cable that covers the top part of the expansion port (on the back side of which I made the mod). Notice the position of the expansion port and the position of the video chip: the analog output is inbetween the 2. that made me think that the video signal is routed first to the analog output and then to the expansin port. Since I had the video disturb also using the analog output, I deduced that the problem could be with the chip, but I'd gladly be proved wrong.

Here is a closeup of the chips

Another closeup of the video chip (a bit blurred, but my camera couldn't focus at that distance, sorry)

Here's an overview of the back side of the board. You can see the expansion port on the lower side with the attached modding wires. On the left there are video pins, on the right side audio pin (I have no problem with the audio output). I used the screws as grounding point.

Closeup of the connections of the mod.

Another closeup. Sorry for the blurriness. Blue red and yellow wires are for R, G and B signals; brown and green wires are respetively for video sync and fast video blanking.

A close side shot of the video connections.

A closeup of the audio connections (as you saw from the board overview, they are on the other side of the expansion connector).

Thanks a lot to everyone than is willing to help me.

Mauro_

What is that just south of your wires on pin 23 and right of R152? Looks to be a blob of solder dropped on the traces. Take a close look at it or a close picture.

- Mike

hmm didn't see the closeups until later. Doesn't appear to be shorting anything.

Ok thanks Michael.

I hope someone can spot something interesting in the pics or give me some other advice.

Thanks to everybody.

Mauro_

You might try the newsgroup rec.games.video.arcade.collecting