new to repairing: malfunctioning console system
 

Hi all.

I'm new to this group and I hope someone can give me an advice.
I was modding a PC-Engine videogame system to have a RGB video output
(by
getting signals I needed straight from the mother board of the game
system). It's not my first time in modding but unfortunately something
went wrong and, even if the mod is working, the video output is not as
it
should be. I guess a video memory bank of the console got fried.

Some sprites are missing and backgrounds in the games look scrambled.
it's
not a malfunctioning of the mod, because the same problem is visible by
using the normal RF output of the console.

My question is: how can I check which is the faulty component? Should I
use a multimeter? How is this kind of testing done?

I'd be glad of reading some howto if anyone wants to point me in the
right
direction, but I'd also love to get a specifical answer.

Tanks a lot.

wrote in message
ps.com...
Hi all.

I'm new to this group and I hope someone can give me an advice.
I was modding a PC-Engine videogame system to have a RGB video output
(by
getting signals I needed straight from the mother board of the game
system). It's not my first time in modding but unfortunately something
went wrong and, even if the mod is working, the video output is not as
it
should be. I guess a video memory bank of the console got fried.

Some sprites are missing and backgrounds in the games look scrambled.
it's
not a malfunctioning of the mod, because the same problem is visible by
using the normal RF output of the console.

My question is: how can I check which is the faulty component? Should I
use a multimeter? How is this kind of testing done?

I'd be glad of reading some howto if anyone wants to point me in the
right
direction, but I'd also love to get a specifical answer.

Tanks a lot.


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:

http://artofwar.free.fr/images_site/...ipeng/pcb2.jpg

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_

wrote in message
ups.com...
James,

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

http://artofwar.free.fr/images_site/...ipeng/pcb2.jpg

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_

It would make more sense for those signals to be integrated
AFTER your mod for RF output. I agree that it's most likely
a "mechanical" issue like a solder bridge or hookup wire short
than a bad chip.

wrote:

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.

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:

http://www.chromozoma.net/pc_engin_mod/IMG_0178.jpg
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.


http://www.chromozoma.net/pc_engin_mod/IMG_0179.jpg
Here is a closeup of the chips

http://www.chromozoma.net/pc_engin_mod/IMG_0180.jpg
Another closeup of the video chip (a bit blurred, but my camera
couldn't focus at that distance, sorry)

http://www.chromozoma.net/pc_engin_mod/IMG_0181.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0182.jpg
Closeup of the connections of the mod.

http://www.chromozoma.net/pc_engin_mod/IMG_0183.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0187.jpg
A close side shot of the video connections.

http://www.chromozoma.net/pc_engin_mod/IMG_0184.jpg
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

wrote in message
oups.com...
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:

http://www.chromozoma.net/pc_engin_mod/IMG_0178.jpg
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.


http://www.chromozoma.net/pc_engin_mod/IMG_0179.jpg
Here is a closeup of the chips

http://www.chromozoma.net/pc_engin_mod/IMG_0180.jpg
Another closeup of the video chip (a bit blurred, but my camera
couldn't focus at that distance, sorry)

http://www.chromozoma.net/pc_engin_mod/IMG_0181.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0182.jpg
Closeup of the connections of the mod.

http://www.chromozoma.net/pc_engin_mod/IMG_0183.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0187.jpg
A close side shot of the video connections.

http://www.chromozoma.net/pc_engin_mod/IMG_0184.jpg
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_

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

wrote in message
oups.com...
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:

http://www.chromozoma.net/pc_engin_mod/IMG_0178.jpg
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.


http://www.chromozoma.net/pc_engin_mod/IMG_0179.jpg
Here is a closeup of the chips

http://www.chromozoma.net/pc_engin_mod/IMG_0180.jpg
Another closeup of the video chip (a bit blurred, but my camera
couldn't focus at that distance, sorry)

http://www.chromozoma.net/pc_engin_mod/IMG_0181.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0182.jpg
Closeup of the connections of the mod.

http://www.chromozoma.net/pc_engin_mod/IMG_0183.jpg
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.

http://www.chromozoma.net/pc_engin_mod/IMG_0187.jpg
A close side shot of the video connections.

http://www.chromozoma.net/pc_engin_mod/IMG_0184.jpg
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_

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


wrote in message
ups.com...
Ok thanks Michael.

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

Thanks to everybody.

Mauro_