NESRGB Help

[Tory4]

Hey guys, have some issues I really want to resolve with this NESRGB. My issue is I have no video at all, it's just a black red tinted screen from the multiout I installed and a white screen from the stock composite output (I know it's not supposed to work anymore)

When the console powers on the LED1 lights up on the NESRGB. I set my console to change palettes by means of the controller but I cannot change them (LEDs do not cycle). The continuity from the controller pins to the board was checked and no shorts. I did however open J1 and closed J2 and I can get the pallets 1 and 4 to alternate that way. I do not get a LED0 (unable to get one either by doing the turn off NESRGB board sequence on the controller) and no LED7 blinks (I put the timing capacitor in).

The PPU was checked for shorts and nothing there either. I did find however the clock pin has no continuity from the header to the PPU itself and according to Tim Worrhington's document it appears there should be a trace bridging the two. I did put a little repair in there to bridge them but no difference (should I leave the repair in?). My PPU came out clean and I did not cause any physical damage to it (all pins were in tact). I also researched numerous cases where people damaged their PPUs and they advise they get very hot... Mine does not do that.

-NESRGB is the 4.2 revision I believe
-NES Front Loader US NTSC
-Sony BVM14H5U is my monitor. Everything is working on this monitor, I use the same multi-out cable for my SNES/N64 and it works well.

Jumper info:
I have J1, J5, J6, and J10 currently closed (soldered)
I am using the provided (external) 5v power supply and it is providing a healthy 5v. I am using a factory power supply.

I could really use some help here if anyone has anything to add. I do have a nice oscilloscope that was my dad's but I honestly might need some help what ranges to put it in.

[Tory4]

I just received an email from Tim he advised me the NES is not running and it all makes sense with the pallets not changing because "the NESRGB board doesn't poll the controller itself, it just listens in on the data when the game does it. If the game isn't running the NESRGB controller interface doesn't work."

I also received the following checks:

-Check 5v supply (already done)

-"Then turn off the console and check the continuity between all pins from the PPU to the motherboard. They all connect through except for pins 2-9 and pins 14-18 which do not. If that's all OK, you can do a passive test on the NESRGB board to see if any of the inputs/output pins have failed."

-"Remove the NESRGB board from the console (leave the PPU on) and measure the resistance to ground on pins 1 to 19 and 21 and 22 of the PPU. Then pins 2-9 and 18 that normally go to the motherboard. They should all be very high resistance (mega ohms or infinite) except for pins 14-7, which should measure 10k ohms and pin 22, which should be 100k ohms. If you find one that is unusually low, it usually indicates a fault."

On the clock trace that has been out since revision 2 on the NESRGB board so I will undo that patch before anything.

I am putting all this out there for the next guy who has this issue. I do plan on fixing this even if my PPU is fried, it may just take me some time.

[Tory4]

Hey guys so my PPU "appears it might be ok. The only variance I found was pin 22 was about 55k ohms. I checked with Tim to see if he thought that could be a fault. Any additional feedback is apprecaited.

I did order in a new 72 pin connector (NES original restored) I just figured I would try it at this point...

[Tory4]

Update:

72 pin did nothing (at least I am using an OEM 72 pin now I guess...)

Anyways, I pulled out my osciliscope and checked pin 18 (clock) at the PPU... Nothing... I took a picture of the scope and showed it to Tim. He told me to check the resistor that takes the signal off the header (I was tired last night and didnt think to do this). I will do it to night. If no signal there, I will remove the board from the header and check pin 18 there (im pretty sure this will have the same result as I checked the contiunity between the pins already. If nothing there I would assume the crystal is bad...

Has anyone had one of these go bad?

[Ben Boldt]

I have a Famicom where the clock is kind of weak and wasn’t getting high enough to drive a CMOS input. This is something you could see with a scope.

[Tory4]

So after doing some more in depth work with the scope I found the crystal is good, The board is getting the clock signal and it is being sent to the PPU. I am going to pull out the PPU and reinstall it in my NES MB. If the system runs Tim is going to send me a new board and he will deem the NESRGB board as bad.

He did not advise if the 55ohm resistance at pin 22 was a fail or not so it will be interesting to see if the system works without the NESRGB board. One thing I am going to do in this is I am going to install a IC socket to the NESRGB board rather than soldering the PPU directly to the board. I want to do this in the event the PPU goes bad. I am going to purchase another for the CPU I will install that at some point. If the NES does not run I will get another PPU off eBay and see if that works.

Honestly Im speculative to the NESRGB board being bad but im glad he is working with me to get this fixed. I will be doing this in the next few days.

[Tory4]

Alright guys, the issue was actually the NESRGB Board itself. TIm warantied it for me no issue. I finally have a semi working NES again and Im super happy. One issue... Sometimes the NES will not start. The unit is outputting power, the Red LED will not come on. The silver power regulator is outputting 7 and 5 volts where it should.

Things I have done:
-Swapped switches (POWER and RESET switch)
-Swapped 72 pins.
-Tried 3 different known working PSUs (2 OEM, 1 aftermarket)
-Changed the stock voltage regulator with another OEM unit
-Swapped 5v regulators which supply the NESRGB board (Dont have mine feeding off the stock regulator)

Eventually turning the power button on and off I will get it to come on. Besides that the NES works great.

What are we thinking? Caps?