SNSP-CPU-1CHIP-01 black screen

As per the title.
There is no audio either.
The board is in very good condition with no obvious signs of damage.
I have replaced the reset button, replaced the 2.2uF cap and the 2 10uF caps, swapped over the S-APU chip for another known working one, removed the cart slot and tested traces running under it and to the S-APU but with no change.
The voltage regulator is outputting 4.99v which is surely close enough to 5v, and obviously not over 5v which could cause problems.
There is a slight flicker on screen when I press the reset button, but this probably doesn't mean anything?
Do any of the engineering geniuses have any ideas?
I really hate to scrap a 1 chip console.

 

I’ve seen a lot of problems with the analog circuit on the rgb boards, maybe start looking there especially if you are getting no signal instead of a true black screen, also look for bad traces

 

You wouldn't happen to have a copy of Mario Kart to try in it?
I had a 1CHIP (which I couldn't fix) with a black screen but Mario Kart would show the Nintendo logo and freeze there.

 

Yep, try a few (many) different games.
On 1Chips, the S-APU tends to fail. Without it, games hang when they initialize sound.
Some games show some graphics before doing that, so when you get that, you know what the problem is.

 

How did you remove the cart slot, I thought they were soldered in?

 

I used a desoldering gun to remove the cart slot. Can anyone point me towards any images showing the traces on the underside of the board underneath all that lacquer?

 

I have swapped over the DAC and S-RGB chips but with no improvement. I am beginning to suspect it is one or more of the SMD components in this area on the underside of the board.

 

Thanks for sharing, you've done so much so far. It would be really amazing if you could fix it in the end. Keep us posted

 

Build a test cart (https://tcrf.net/SNES_Test_Program)

 

I have the test ROM on my everdrive, but that won't even work on this console.

 

That defeats the purpose. The test carts frequently initialize properly even on broken consoles. But on a broken console, getting through the flash cart menu might require more of a functional console to begin with.

 

What specific parts do I need to make one? I assume it will only need a basic cartridge PCB like an SHVC-1AON as a donor?

 

That, and either a TSOP adapter or a 27C801 eeprom is the easiest way.

 

I acquired the chip programmed with burn-in revision D (from BadAd) and made a burn in cartridge, but it won't even load that. I tested the cartridge on another PAL SNES to make sure it works.

 

Damn, nearing the end of the road

 

Well unless you have a donor for spare ic's you're pretty much out of luck