Issue 2 48k Yellow Display

Hi guys.

As the title says, I have an issue 2 that's displaying the typical yellow/green colour screen at switch on. The picture is clear and stable, but yellow.

So far I have done the following...

Checked voltages as per Zorns initial startup test video. All memory voltages present and correct.
Component video mod.
Recapped. Checked cap values before replacing all good. Installed in the correct polarity.
TR4 TR5 removed, checked tested good, refitted.
Replaced LM1889N with new one, no difference.
Replaced voltage regulator.
Tried to adjust VR1/2 trim pots, no difference..
Replaced VR1/2 with ones from another board, no difference.

The speccy does appear to be working fine - I have not tested with a keyboard yet, but it's not buzzing or anything, it's just got a yellow display. Adjusting the trim pots will alter the picture from blue to horizontal stripes etc, but I cannot get a white display.

Here's a pic.

I am out of ideas here.

I will have access to a scope as I picked one up on Kijiji, collecting it tomorrow. It's a Siglent SDS1052DL. I am looking forward to learning how to use it - at least the basics anyway.

Any advice would be appreciated.




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