NESRGB problem for Twin Famicom

[VEGETA]

Hello,

I have tried to install NESRGB for the twin famicom, followed everything precisely but it doesn't work. I am using classic OSSC.

Please check the images here for the installation: https://imgur.com/a/nHUlz8O

I admit I used a lot of heat via soldering iron on desoldering PPU but I don't think it was to the degree of breaking it. 3 of PPU legs got broken while I was taking it out, thus I installed external wires to make the required connections as seen in photos. I verified scart rgb wires via continuity test and all worked fine. However, scart led doesn't light up (the scart + audio wires bought along the kit from oldskool) but 5v is there. of course, grabbing csync via oscilloscope resulted in nothing.

I have tested this twin famicom and it worked perfectly fine via composite on HDTV. However, it needed for me to wiggle the cartridge in order to make the connection but eventually it worked fine.


what should I do to solve this?

I can:

1- remove the nesrgb board and re-install the ppu then test it on same hdtv via composite. how to do it on the socket while it is in the back side now? I can gently solder the legs on original place though.

2- get a new verified and tested NES PPU and install it in its place. where can I buy one?


I am really frustrated after so much effort that I got this! I even recorded everything to make a high quality video on my channel!

For your kind help.

[mikejmoffitt]

I recommend against using those wires as you have there. Instead, you will be able to do neater and more reliable soldering work if you get some ~28 gauge hookup wire, and cut neat wires of appropriate length with only the required amount of copper exposed on each end.

[VEGETA]

I recommend against using those wires as you have there. Instead, you will be able to do neater and more reliable soldering work if you get some ~28 gauge hookup wire, and cut neat wires of appropriate length with only the required amount of copper exposed on each end.

I know they are not optimal but I have enough space to use them, plus they are so sturdy unlike what they look like. I have verified them to be working via multimeter continuity.

I think the problem is not in these wires, can you help in it?

[VEGETA]

I found a broken cut trace where I used to desolder, it is the one connecting PPU pin 2 to CPU pin 28 which is D0. check image to see: https://imgur.com/a/LcSM8wn

is this lone trace enough to never show any image at all?

I will wire a trace either from PPU to that pad directly or try to patch that very small trace.

EDIT: I patched the trace itself with solder and verified that it is connected properly. still didn't test it.

[VEGETA]

After patching that trace, OSSC started recognizing the sync!! it showed 15 khz but 60.31 hz, 60.08, and bunch of other weird values. Image never showed on TV and I didn't connect the audio. Does this mean that the system really works?

I tried wiggling the 3 cartridges I have but it didn't sync properly. I used to do this for the super famicom until it eventually got it right, but this twin famicom is no use. settles on 60.31hz most of the time and no image.

but right after I wired the Y (in ypbpr) to the ossc it stopped getting any sync signal at all despite trying a lot which is weird considering it just recognized sync. which leads to step 2 mentioned below:


I disconnected NESRGB board and found that some of the connectors shown in this image are not connected together (no continuity): https://imgur.com/a/a2EgRr9

aren't these 2 rows supposed to be connected together? all other connections seem perfectly fine. However, there are about 5 or so pins that doesn't reach between the nesrgb and adapter board. while I checked the ppu and all of its pins are reaching the adapter board just fine.

So the discontinuity is between the NESRGB and adapter board. Should they actually be connected together? if so, then I will do external short wires and try again tomorrow.

[VEGETA]

Hello

it turns out that the rgb din small adapter board had a short from gnd to csync for some reason. thus I removed it.

I have connected Y in ypbpr to ossc and now it shows 60.08 hz and 60.05 hz nearly all the time. with and without cartridge!

if I wiggle cartridge couple of time it can reach something like 60.01 or 60.22.

what to do now?

[VEGETA]

I have wired the switch according to 2nd configuration here: https://etim.net.au/nesrgb/switch/

I hooked the original composite jack to OSSC Y input since it recognizes sync signal, but it gives the same 60.05 and 60.08hz sync signals regardless of switch position, with and without cartridge!

does this mean that the PPU itself is bad?

[mikejmoffitt]

On the adapter, it is expected that some pins will not be connected as you have described. It is necessary for some of the data pins on the PPU to go through the PCB itself in order for the NESRGB system to filter write to the palettes and registers. Forcing a connection where there should not be one will not cause things to go well.

I think you should not read too strongly into the precise refresh rate. It is more likely that the measurement has a margin of error. The presence of a cartridge or wiggling thereof is not going to influence the scan rate of the fixed PPU system. If it fixed your Super Famicom, it is only because the software was not starting before it was moved or cleaned. In the case of the Famicom, you will receive a sync even with no software running (a solid color screen).

It is unlikely that the PPU is bad.

[VEGETA]

On the adapter, it is expected that some pins will not be connected as you have described. It is necessary for some of the data pins on the PPU to go through the PCB itself in order for the NESRGB system to filter write to the palettes and registers. Forcing a connection where there should not be one will not cause things to go well.

I think you should not read too strongly into the precise refresh rate. It is more likely that the measurement has a margin of error. The presence of a cartridge or wiggling thereof is not going to influence the scan rate of the fixed PPU system. If it fixed your Super Famicom, it is only because the software was not starting before it was moved or cleaned. In the case of the Famicom, you will receive a sync even with no software running (a solid color screen).

It is unlikely that the PPU is bad.

I didn't modify or bridge anything at all. Also, I have wired the switch according to previous reply. therefore either nesrgb is on, or it is off. when on I tested Y from YPbPr and when off I tested original composite signal. both had the sync detected but no picture at all via the OSSC.

as a final desperate test i will try it on my HDTV back home when I return next week which accepts composite and component, both 240p. the same HDTV which accepted the original composite previously.

if the PPU is not bad, and the connections are all ok... then what is the reason why ossc doesn't load the image? I don't think I need the dejitter mod or anything since it is already in latest nesrgb right?

can you suggest something?

[Syntax]

When the RGB mod is switched to off you must use the original composite signal. Using the regenerated one causes issues.
This is because no palette is available for the regenerated composite, it either wont start or have bad graphic glitches/missing sprites text ect.

Doing mod work with those crappy pin header wires is a joke. They are usually thin wire that snaps internally at the connector, and are a main point of failure. And your solder joints look cooked dry.
Go get some decent wire and learn how to do it properly.

Your NESRGB kit will be fine, Tim checks everything himself ive never had an issue.

OSSC locks onto whatever it feels like, you never get a solid 60 or 50 with a NES. Why are you even testing without a game?

[mikejmoffitt]

can you suggest something?

I'm suggesting you redo your wiring properly, and check that all the mod work done can be trusted. You may think those wires are fine, but everyone here with more experience and confidence will tell you that using those wires is a poor choice, and you will benefit yourself by doing it correctly. They may not be the problem at hand, but - to put it bluntly, if you think the wiring shown is acceptable, then it raises the question of what other problems may lurk behind similar quality work.

Beyond that, use an oscilloscope to look for missing or problematic signals. Other than that, anything I or anyone else suggests would be a fantasy because there isn't enough information to work with.

Honestly, get a simple game that makes music immediately upon boot (like Adventure Island, Devil World, whatever) and don't even worry about the video until you can hear the game sounds and trust that it is running at all in the first place.

[VEGETA]

When the RGB mod is switched to off you must use the original composite signal. Using the regenerated one causes issues.
This is because no palette is available for the regenerated composite, it either wont start or have bad graphic glitches/missing sprites text ect.

Doing mod work with those crappy pin header wires is a joke. They are usually thin wire that snaps internally at the connector, and are a main point of failure. And your solder joints look cooked dry.
Go get some decent wire and learn how to do it properly.

Your NESRGB kit will be fine, Tim checks everything himself ive never had an issue.

OSSC locks onto whatever it feels like, you never get a solid 60 or 50 with a NES. Why are you even testing without a game?

I switched off the palette as indicated in schematic, so now original composite is the only available one. I have used the original composite from its original jack, not encoded one.

I do have regular wires but they are also thin, but yes more stable than those. tonight I will redo all wiring and see if they will work.

plus, I tested 3 games and no games but same result. I assume ossc should work properly with NES even if it shows 60.05 or 60.08 right?

[VEGETA]

I removed all wires and done them properly this time as you can see, I only wired YPbPr and Audio since others are not needed now. tested all wires and shorts of any kind, all reach its destination.

I still get the same result. I even replaced the cap near the reset button since I read somewhere it can be bad and cause system to never start... put a new one while the old one was ok after testing it.

When I press the reset button I get graphical glitches as you can see in the images here: https://imgur.com/a/jTIGS0p

Also, I noticed that the front light here: https://imgur.com/a/JhgwRDu does not turn on, I don't know what this could be despite it is connected and never removed. while the front light of the power button turns on nicely.

what do you think?

[Syntax]

Put the PPU back in socket and test the system to see if it boots, if it doesn't then repair it and retry the mod.

Clean the cart slot with some cardboard or folded paper sprayed with iso, it will act as a very mild abrasive.
Inspect and retension loose fitting pins.

[VEGETA]

Put the PPU back in socket and test the system to see if it boots, if it doesn't then repair it and retry the mod.

Clean the cart slot with some cardboard or folded paper sprayed with iso, it will act as a very mild abrasive.
Inspect and retension loose fitting pins.

is that light supposed to be on when I turn the system on? despite the power button led is on.

The system is clean and I tried cleaning cartridge and pins to my best but I will try again. last time before the mod it worked after quick cleaning but this time I cleaned the carts several times without result. I never tried to clean the cart socket itself but as I said it didn't give a problem previously.

what potential loose pins to be checked?

also, the toggle switch can be put to "gnd" which disables the mod entirely... but now i cannot test it as there is no system which accepts cvbs here, I would need to get back home till thursday. will surely try it since that tv worked with cvbs previously. I don't prefer to re-solder the ppu back, especially that with switch position to gnd is the same thing.

[Syntax]

Plug in some headphones till you get home and listen for audio like mikejmoffitt suggested.

[VEGETA]

Plug in some headphones till you get home and listen for audio like mikejmoffitt suggested.

I could not listen to anything, I hooked my PC speakers to it.

[Syntax]

Ppu is socketed both sides and putting it back to normal to test should take 5 minutes

[mikejmoffitt]

Right, this:



What is this? Are you positive those pins should connect the way you have soldered them? As mentioned before, some will pass through, but others will not.

[VEGETA]

I have verified that they were correct but nonetheless I took it out, then did as this image here: https://imgur.com/a/W34jYYi

I put those wires to touch the socket pins, then installed the ppu and soldered the wires to respective ppu pins. this (and previous connections) were because those ppu pins were cut\broken so they didn't reach the socket pins.

Result is the same.

Now it is verified that all wiring and connections are good... yet, still no result. Could be that the ppu itself went bad due to excessive amount of heat I used to take it off? but if so, then why it outputs this sync signal?