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Author Topic: Noise on RGB signal. Suggestions? (Read 2381 times)

Offline John Fante

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Noise on RGB signal. Suggestions?
« on: 2020.September.15. 21:18:39 »
I managed to recap my "new" Egyptian EP and update to EXOS 2.4 :)

The machine works but I still have a strange noise problem on the RGB signal. See here.

Any suggestions how to find the source for that?

As far as I can see the components are fine but maybe something "broke" when I turned it on the fist time?

At first boot the machine was dead. Red LED on but no picture. With the help from this thread i managed to get it going.

The 5V rail was fine but 12V was way too low which cause the TR2 to fry (maybe killed by a bad C9). I replaced TR2 and C9 and the machine came to life :) But now I have a noise problem (see video).

To cure that I then recapped the board (took a while :) ). That is finished now but the noise is still there.

Any suggestions to where I should start looking for the error?
« Last Edit: 2020.September.16. 08:46:00 by John Fante »

Offline John Fante

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Re: Noise on RGB signal. Suggestions?
« Reply #1 on: 2020.September.24. 12:57:38 »
A quick BUMP :)

Any suggestions would be highly appreciated :bow:

Offline Zozosoft

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Re: Noise on RGB signal. Suggestions?
« Reply #2 on: 2020.October.01. 11:36:57 »
Just a quick idea: this board have the extra GND patch wires? These are missing from most of EP64 machines, EP128 machines come with these. Services got a instructions if any EP64 arrived to repair, also install these to the motherboard. (Somewhere I have a document talking about these)
There are two at bottom side.
And one from the ROM chip to the expansion connector.