Atari 8000XE black screen

[Martin72]

I have an Atari 800XE PAL machine and I have extend it to 128K memory with 2 additional 4464 Dram chips and a co25953 replacement. The computer works fine when I use it with the RF output but when I connect it to the composite output I have only sound and a black screen. The cable works fine with another 130XE so this is not the problem. I think the problem is in the modulator because the composite signal is created in this box, does someone has a schematic of a PAL 800XE or 130XE modulator?

Edited November 23, 2022 by Martin72

[Peri Noid]

i think it's this one:

 

Edited November 23, 2022 by Peri Noid

[Peri Noid]

[remove please]

 

Edited November 23, 2022 by Peri Noid
Wrong data, my bad.

[Martin72]

Thank you for the schematic. In the meanwhile, the problem has been solved, one of the connections of the modulator was badly soldered on the mainboard.