Display issue on rev 6A motherboard with DIVMMC Future
I received the system along with a ZX81 and a +3 model both of which have now been restored to full working order and I thought I had done hte same with the rubber key model.
The machine has had capacitors replaced, a new keyboard and membrane and a new metal backplate for the keyboard as the old one was dinged to hell and back and peeling off. I also performed the capacitor od for the modulator to allow composite video.
I then bought a DivMMC Future direct from TFW8B and am seeing an odd issue.
Basically when the unit powers on I get a normal display, when the DivMMC is activated, the display gradually dims, the picture is still visible and I can load and run software but the display is very dark.
Thinking it was a power issue, I replaced the 7805 regulator and the PSU with new versions but still seeing the same issue.
Where would be the best place to start troubleshooting?