NESRGB Troubleshooting (Frontloader)

[Meista]

Hi,

I recently bought a used NTSC-Frontloader that came with an NESRGB pre-installed.
The seller claimed that that the connection between the board and
the socket was very loose so that 90% of the time the image is messed up.

I thought to myself, this should be an easy fix and bought the console (extremely cheap !).

When it got here, it was exactely like the seller stated. The board was indeed very loose in the socket.
50% of the time i would only get a black screen (resetting the console would create some glitching lines),
49% of the time I only got glitched images, sometimes with sometimes without music and
1% of the time I would get a perfectly fine picture with music, so the PPU was still fully working.

The TV also changed to the correct channel after turning the console on every time, so some kind of signal was
getting out no matter what.

I then bought a new socket, desoldered the old one (I did a bad job, more on this later) and put the new one
in. After putting everything together, all I got was a black screen, with no music and some glitching lines when resetting the console.
The TV was still changing to the correct channel. So again, some kind of signal was still going to the TV.
The channel numbers or the channel overlay (sorry, I don't know what it's called in english) was/were extremely distorted at this point.

After that I started checking some things (I got a few hints from other threads)

- No legs of the socket were accidentally bridged
- Continuity between the PPU and legs of the new socket is ok for all pins but 2-9 and 14-17, which should be ok.
- Measuring between 5V and ground on the NESRGB board gives me a resistance of 2,2k.
- Measuring between ground and pins 2-9 on the NESRGB board gives me a resistance of sth. around 26M for all pins.
- I hardwired the palette (ground and pad 3) to eliminate any problems with a switch
- Continuity is ok for all the lines (RGB, sync, audio etc.) that feed the DIN-connector

This "should" be ok, I guess ?

I mentioned earlier, that my desoldering job wasn't the best, so I checked the bottom of the motherboard for damaged
traces or pads. And sadly, I found at least one. The pad of pin 18 didn't connect to the trace anymore so I had to
bridge it with a wire. This helped a little. While the picture was still black with no music, the overlay/channel
numbers weren't distorted anymore.

I continued to check for continuity for the rest of the socket legs, pads and traces.
My ability to read and understand schematics is very limited unfortunately, so I was only able to check
obvious connections.

Here's what I found.

The following pins were still connected to traces on the bottom of the motherboard:
5, 6, 8, 9, 10-13, 18 (fixed/bridged), 23-38, 40

And the following pins were still connected to traces on the top-side of the motherboard:
1, 14-17, 19-22, 39

Do any of these pins have a connection on the bottom AND the top side of the motherboard ?

I didn't know where to check pins 2,3,4 and 7 (are these even important anymore, since there isn't any continuity from the PPU anyways ?)

This is where I'm at now, and I have run out of ideas

Any help would be appreciated.

[Spacemonkey]

Hi,

I recently bought a used NTSC-Frontloader that came with an NESRGB pre-installed.
The seller claimed that that the connection between the board and
the socket was very loose so that 90% of the time the image is messed up.

I thought to myself, this should be an easy fix and bought the console (extremely cheap !).

When it got here, it was exactely like the seller stated. The board was indeed very loose in the socket.
50% of the time i would only get a black screen (resetting the console would create some glitching lines),
49% of the time I only got glitched images, sometimes with sometimes without music and
1% of the time I would get a perfectly fine picture with music, so the PPU was still fully working.

The TV also changed to the correct channel after turning the console on every time, so some kind of signal was
getting out no matter what.

I then bought a new socket, desoldered the old one (I did a bad job, more on this later) and put the new one
in. After putting everything together, all I got was a black screen, with no music and some glitching lines when resetting the console.
The TV was still changing to the correct channel. So again, some kind of signal was still going to the TV.
The channel numbers or the channel overlay (sorry, I don't know what it's called in english) was/were extremely distorted at this point.

After that I started checking some things (I got a few hints from other threads)

- No legs of the socket were accidentally bridged
- Continuity between the PPU and legs of the new socket is ok for all pins but 2-9 and 14-17, which should be ok.
- Measuring between 5V and ground on the NESRGB board gives me a resistance of 2,2k.
- Measuring between ground and pins 2-9 on the NESRGB board gives me a resistance of sth. around 26M for all pins.
- I hardwired the palette (ground and pad 3) to eliminate any problems with a switch
- Continuity is ok for all the lines (RGB, sync, audio etc.) that feed the DIN-connector

This "should" be ok, I guess ?

I mentioned earlier, that my desoldering job wasn't the best, so I checked the bottom of the motherboard for damaged
traces or pads. And sadly, I found at least one. The pad of pin 18 didn't connect to the trace anymore so I had to
bridge it with a wire. This helped a little. While the picture was still black with no music, the overlay/channel
numbers weren't distorted anymore.

I continued to check for continuity for the rest of the socket legs, pads and traces.
My ability to read and understand schematics is very limited unfortunately, so I was only able to check
obvious connections.

Here's what I found.

The following pins were still connected to traces on the bottom of the motherboard:
5, 6, 8, 9, 10-13, 18 (fixed/bridged), 23-38, 40

And the following pins were still connected to traces on the top-side of the motherboard:
1, 14-17, 19-22, 39

Do any of these pins have a connection on the bottom AND the top side of the motherboard ?

I didn't know where to check pins 2,3,4 and 7 (are these even important anymore, since there isn't any continuity from the PPU anyways ?)

This is where I'm at now, and I have run out of ideas

Any help would be appreciated.

Poor system, bad install then a botched repair job.

Probably easiest for you to get a replacement NES board and install the NESRGB on that.

[Meista]

Poor system, bad install then a botched repair job.

Probably easiest for you to get a replacement NES board and install the NESRGB on that.

Alright, thanks for the pep talk.

So, after some more investigating/measuring I am now 100% certain that no other traces were damaged
during the removal of the old socket (apart from the one I broke and repaired), but I still can't get a picture
when the board sits firmly inside the new socket, even though there is continuity from the legs of the PPU to
the legs of the socket on the underside of the board.

Now here's where it gets weird. In one last desperate attempt I started wiggling the board around a little, and
just like before with the old socket, in a few positions, the console works perfectly.

I have no idea why, but this does at least show, that all of the components are still working fine.

Does anyone have any idea, what I could check next ?

[Star1]

In regards to your first post, pins 2, 3, 4 and 7 have connections to both the cpu, and cart connector (cc).

2 goes to cpu pin 28 and cc pin 43
2 goes to cpu pin 27 and cc pin 42
4 goes to cpu pin 26 and cc pin 41
7 goes to cpu pin 23 and cc pin 38

Obviously you want a stable connection on both ends.

[Meista]

In regards to your first post, pins 2, 3, 4 and 7 have connections to both the cpu, and cart connector (cc).

2 goes to cpu pin 28 and cc pin 43
2 goes to cpu pin 27 and cc pin 42
4 goes to cpu pin 26 and cc pin 41
7 goes to cpu pin 23 and cc pin 38

Obviously you want a stable connection on both ends.

Thank you, those connections are ok.