MegaSTE Repair Continued - Video Noise

[geogeo_28]

Moving around the 32MHz wire as far away as possible of the video signal did nothing.

[displaced]

So just to wrap up from my side:

Have swapped back to the old PSU and the noise has immediately returned. Have ordered exxos’s recap kit for my model PSU, and I’ll keep the Meanwell as a nice multi-volt test supply. I’ve got a bare STE board I can use it on for tinkering.

Thanks all for your help - I should’ve just recapped the damn thing straight away, but I got swayed by its apparently decent output and the good rep that the MSTE’s PSU has!

[rubber_jonnie]

So just to wrap up from my side:

Have swapped back to the old PSU and the noise has immediately returned. Have ordered exxos’s recap kit for my model PSU, and I’ll keep the Meanwell as a nice multi-volt test supply. I’ve got a bare STE board I can use it on for tinkering.

Thanks all for your help - I should’ve just recapped the damn thing straight away, but I got swayed by its apparently decent output and the good rep that the MSTE’s PSU has!

PSUs are usually worth recapping from the off, though the rest is normally OK.

[displaced]

Yeah - don’t know why I didn’t just go for it. Always seems like a big job for amateurs like me. But I’ve done it once before on an Archimedes, and have replaced caps elsewhere with success. And PSU caps are usually nice and chunky on not especially dense PCBs - so not technically difficult, just needs a good amount of care!

[geogeo_28]

I guess I will try an other PSU and see if this has an impact on the noise.

[exxos]

I guess I will try an other PSU and see if this has an impact on the noise.

If your using my PSU then it has like x10 less noise than original ones, so it wouldn't make any sense if a different PSU solved the problem.

[geogeo_28]

As expected, switching to the original PSU did literally nothing.
I guess I have to take a closer look to the video circuit. :/

[exxos]

As expected, switching to the original PSU did literally nothing.
I guess I have to take a closer look to the video circuit. :/

I don't remember if you have done this fix.. it may help on a STE anyway with your issue..

https://www.exxosforum.co.uk/atari/last/ ... /index.htm

[geogeo_28]

Yup I did this fix. It removes the ghosting but not the noisy vertical lines.

[geogeo_28]

Looking more into this issue. The white lines now starts to be visible at NTSC 60 Hz.
I suspect U401 C301712-001 is failing.
Unfortunately, I don't have a spare part to verify this hyptohesis quickly. :/