Jailbars on a front loader NES - help required

[viper1701]

Hi guys,

I’m trying to get an old French NES to work

I’m having those strange vertical interference, particularly visible on the blacks.



At first I thought there was something wrong with the av out module so I’ve replaced it entirely with the same result

I then changed all the cap on the main board... same

Then replace the cartridge connector... same.

Any idea ?

PS: I also tried to get the image directly from Pin 20 of the PPU and even though the image was quite dark it seems there was no such black bars.

[viper1701]

Hi guys,

Other things I ve tried :

Replace the PPU - no effect
Replace Q1 - no effect

I’m really at a lost. The PCB looks absolutely fine. I’m sure there must be a coupling issue somewhere but I really don’t know.

[nissling]

Since it's a French Nes, I'm assuming you're using its RGB output (simply composite converted to RGB unless modified)? It's a very old design to say the least so that could very likely be the issue.

The only solution that makes sense IMHO is to replace it with an NesRGB board, or get a new console. A defective composite to RGB board with comb filter from the 80s isn't really worth repairing if you ask me.

EDIT: Should be mentioned that the PPU itself isn't any different on the French units compared to other European ones. Only the final stage before output differs.