PC-Engine Duo R RGB Mod Dim Picture

[doaal]

Hey all, I picked up a Duo R and the RGB mod from oldskoolconsoles as they were one of the only options I could find with good European shipping. However after installing the mod I get a dim picture from my console.



And here's my handiwork:



I know. Not the cleanest joints. I don't have the steadiest hand for fine soldering. But I've wiggled the wires to make sure the connection is secure and none of the wires on IC903 are bridging adjacent pins.

The strange thing is, if I ground any of the pins sending R, G or B signals, the picture brightens up. It's like the amp can't combine all three signals at full brightness. I also get full brightness when using a composite cable, but that's in black and white as my TV is PAL and can't do NTSC colour.

I've done the jailbar fix by replacing resistors as detailed on Console5 but used the resistors bundled with their cap kit rather than what came with the RGB mod.

Duo-Rs aren't known to have capacitor issues but I did recap the board regardless.

I'm using a nice SCART cable (sync on composite) from retrogamingcables. Probing the output side of the amp, I get ground and +5v. Could the amp itself be at fault?

 

[GohanX]

I'm just taking a wild guess, but maybe try pulling 5V from the voltage regulator instead of the cap? It shouldn't matter, but I don't really see anything else wrong. The only other possible thing I see is that it looks like where the power and ground are soldered to the cap the wires are only hanging on by a couple of strands, maybe that needs to be cleaned up a bit.

 

[doaal]

I'm just taking a wild guess, but maybe try pulling 5V from the voltage regulator instead of the cap? It shouldn't matter, but I don't really see anything else wrong. The only other possible thing I see is that it looks like where the power and ground are soldered to the cap the wires are only hanging on by a couple of strands, maybe that needs to be cleaned up a bit.

I took off the wires from the cap, soldered ground to the power switch and got +5v from pin 61 on IC501 as Voultar does:

But I get the same issue.

 

[Neo Alec]

The wires on the C6260 all look like they're touching adjacent pins to me. Have you tested for bridged joints with a multimeter?

 

[doaal]

The area is dirty as I was going mad thinking it must be those wires bridging, and soldered them again and again. But I'm testing each colour on C6260 with the adjacent pins, and nothing is bridged.

 

[doaal]

I can remove the ground wire and the amp still powers. Not sure how that works as even if one of the other wires is grounded, it can't carry it to the ground pad on the amp. Amp pads aren't being bridged. Tapping ground does flash the picture at different brightnesses, but that could have to do with power fluctuating through the amp. Maybe a voltage issue? Again, reading +5v on both the input and output pads on the amp.

 

[HeavyMachineGoob]

Use thinner wire for the HuC6260 pins, like IDE40 or even IDE80.

 

[city41]

Total random guess: maybe some caps are bad? They are notorious on NEC consoles. Can you run the system but not through the mod? Is the normal pic dim too?

EDIT: ah just saw you already tried this. Damn.

 

[doaal]

Use thinner wire for the HuC6260 pins, like IDE40 or even IDE80.

I'll see what I have around. This is the wire the mod came with and it's been a bitch.

Total random guess: maybe some caps are bad? They are notorious on NEC consoles. Can you run the system but not through the mod? Is the normal pic dim too?

EDIT: ah just saw you already tried this. Damn.

To be thorough, I'll say that the Console5 kit was missing exactly C961, which I've left alone. It's actually right above th GPU (marked with a sharpie in the last photo. But yes, composite works normally (just in black and white thanks to PAL/NTSC woes). Still looking forward to actually playing this thing!

 

[doaal]

Use thinner wire for the HuC6260 pins, like IDE40 or even IDE80.

Temp wiring job with AWG24 wire, demonstrating that I'm pulling ground and +5v from IC501 instead of a cap this time. Same dim picture.

 

[HeavyMachineGoob]

Could be a bad op amp chip on the RGB amp board, I've had that before.

Also, all your solder joints in your newest picture are absolutely awful. Get some flux, some decent quality solder and watch some YouTube tutorials like EEVBlog.

 

[doaal]

I'll clean them up once I know what the issue is. When you're up all night soldering on/off all the same wires you stop caring about keeping things clean.

Emailing the guy that supplied the amp to see if he knows what's up.

 

[Neo Alec]

I can remove the ground wire and the amp still powers. Not sure how that works as even if one of the other wires is grounded, it can't carry it to the ground pad on the amp. Amp pads aren't being bridged. Tapping ground does flash the picture at different brightnesses, but that could have to do with power fluctuating through the amp. Maybe a voltage issue? Again, reading +5v on both the input and output pads on the amp.

Because it's common ground, if you have ground connected anywhere else it would still work. If you disconnect 5v and it still powers, then I'd say you definitely have a short somewhere.

 

[city41]

Emailing the guy that supplied the amp to see if he knows what's up.

See if he can send another one. If regular composite out is working as expected, and the install seems fine, I would start to suspect the amp itself.

 

[doaal]

Waiting for a reply from the seller. In the meantime I've:
-Removed CSNYC from the output as composite is already carrying sync on the cable
-Cracked open the SCART cable to make sure there aren't any resistors on the line that the amp is already providing

 

[doaal]

Four days with no response from the seller. Does anyone know of a PC-Engine RGB amp that ships to the UK? Voultar's mod looks solid but doesn't ship.