AOC CM-735 - problem with red colour

[Rado]

Hello.
I'm trying to repair an old AOC CM-735 monitor. It had cold joint (no
red colour), so I soldered few junctions around transistors (maybe
10). Red colour now works fine, but with few milimetres long flame in
places where red colour goes down. I resoldered junctions again,
cleaned it but nothing. I don't know what should I check now. Can you
help me please?

Thank you.
Rado.

 

[Eric]

could be a sign of a tired picture tube
Hello.
I'm trying to repair an old AOC CM-735 monitor. It had cold joint (no
red colour), so I soldered few junctions around transistors (maybe
10). Red colour now works fine, but with few milimetres long flame in
places where red colour goes down. I resoldered junctions again,
cleaned it but nothing. I don't know what should I check now. Can you
help me please?

Thank you.
Rado.

 

[H. R. Bob Hofmann]

could be a sign of a tired picture tube
Hello.
I'm trying to repair an old AOC CM-735 monitor. It had cold joint (no
red colour), so I soldered few junctions around transistors (maybe
10). Red colour now works fine, but with few milimetres long flame in
places where red colour goes down. I resoldered junctions again,
cleaned it but nothing. I don't know what should I check now. Can you
help me please?

Thank you.
Rado.

I agree with Eric.

Try boosting the filament voltage a little bit by adding a turn or two
to the filament winding on the flyback transformer, if you understand
how the pix tube gets its filament voltage. IT will shorten the
overall life of the picture tube, but it's worth a try.

H. R. (Bob) Hofmann

 

[H. R. Bob Hofmann]

could be a sign of a tired picture tube
Hello.
I'm trying to repair an old AOC CM-735 monitor. It had cold joint (no
red colour), so I soldered few junctions around transistors (maybe
10). Red colour now works fine, but with few milimetres long flame in
places where red colour goes down. I resoldered junctions again,
cleaned it but nothing. I don't know what should I check now. Can you
help me please?

Thank you.
Rado.

I agree with Eric.

Try boosting the filament voltage a little bit by adding a turn or two
to the filament winding on the flyback transformer, if you understand
how the pix tube gets its filament voltage. IT will shorten the
overall life of the picture tube, but it's worth a try.

H. R. (Bob) Hofmann

 

[Rado]

Before I found (I hope) cold junction, red colour had sometimes worked
for short time and without flames. Flames has appeared after
soldering. Couldn't it be just bad capacitor? Blue and green colours
are OK.

Rado.