Resistor exploded in my monitor

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sandord
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Re: Resistor exploded in my monitor

Post by sandord » Mon Dec 24, 2018 11:47 am

exxos wrote:
Mon Dec 24, 2018 11:45 am
Kinda looks likes what happens when got "noisy presets" which control H&V sizes etc.
Perhaps, but the sound is quite alarming, a little too loud for it to just be a dirty pot or something like that.

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Re: Resistor exploded in my monitor

Post by exxos » Mon Dec 24, 2018 11:50 am

sandord wrote:
Mon Dec 24, 2018 11:47 am
exxos wrote:
Mon Dec 24, 2018 11:45 am
Kinda looks likes what happens when got "noisy presets" which control H&V sizes etc.
Perhaps, but the sound is quite alarming, a little too loud for it to just be a dirty pot or something like that.
oh, I dont have sound on normally here so didn't hear it..

I would resolder the large inductors near the LOPT for starters... its possible you may need to identify the one making the noise and take it out and soak it in epoxy to shut it up.
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Re: Resistor exploded in my monitor

Post by sandord » Mon Dec 24, 2018 11:57 am

exxos wrote:
Mon Dec 24, 2018 11:50 am
oh, I dont have sound on normally here so didn't hear it..

I would resolder the large inductors near the LOPT for starters... its possible you may need to identify the one making the noise and take it out and soak it in epoxy to shut it up.
Well, the sound is a few times louder than the usual coil whine. But I'll check the inductors anyway, good suggestion.

But if you look at the video, you can see the picture varying in size, which I think indicates significant power fluctuations. At one point, the picture even goes black for a fraction of a second.

When I recapped the monitor a few months ago, I resoldered like more than half of main board. I definately did the LOPT and the area around it.

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Re: Resistor exploded in my monitor

Post by sandord » Mon Dec 24, 2018 12:00 pm

Could it be that the LOPT pushed the power regulator over the edge?

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Re: Resistor exploded in my monitor

Post by exxos » Mon Dec 24, 2018 12:02 pm

I think you have a bad connection somewhere, either on a preset or wire somewhere, or solder joint. Coils can make the sound in the video. They can resonate and cause the faults you see. I've worked in a workshop for years and heard the row they can make like in the video any many times worse.

You need to start eliminating "classic" faults one at a time. You may have more than 1 fault as well.
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Re: Resistor exploded in my monitor

Post by sandord » Mon Dec 24, 2018 5:09 pm

exxos wrote:
Mon Dec 24, 2018 12:02 pm
I think you have a bad connection somewhere, either on a preset or wire somewhere, or solder joint. Coils can make the sound in the video. They can resonate and cause the faults you see. I've worked in a workshop for years and heard the row they can make like in the video any many times worse.

You need to start eliminating "classic" faults one at a time. You may have more than 1 fault as well.
I agree. I just ran the monitor in the dark and there's absolutely nothing too see except for the heater.

When I get to it, I'll resolder the inductors and see what happens.

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Re: Resistor exploded in my monitor

Post by PaulJ » Mon Dec 24, 2018 5:39 pm

Some times if you have a short in an individual winding that encompasses a few turns of that winding it acts as a shorted secondary for those few turns of that winding. It can case an increase in noise and generates extra heat which will cause the driving device to fail. Does the other monitor exhibit the increase noise. If not can you swap the transformer?

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Re: Resistor exploded in my monitor

Post by sandord » Tue Dec 25, 2018 12:26 am

PaulJ wrote:
Mon Dec 24, 2018 5:39 pm
Some times if you have a short in an individual winding that encompasses a few turns of that winding it acts as a shorted secondary for those few turns of that winding. It can case an increase in noise and generates extra heat which will cause the driving device to fail. Does the other monitor exhibit the increase noise. If not can you swap the transformer?
That other monitor doesn't work. The previous owner told me it suddenly failed on him. The power led doesn't even light up so it probably has power supply issues as well. As I took the power regulator from it, that part may be (partially) faulty as well. I ordered replacement parts but it may take a few weeks for them to arrive.

If resoldering doesn't help, I might indeed try to swap the transformer.

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Re: Resistor exploded in my monitor

Post by sandord » Sat Dec 29, 2018 10:41 am

I think it might be the tube neck connector, I carefully pushed a corner of the neck board with an insulated screw driver and I think the hissing almost went away.

I'm going to let the monitor settle down for a few hours and then discharge the large caps, before taking the neck board off and de-oxidising the connector leads.

I hope that'll do it!

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Re: Resistor exploded in my monitor

Post by sandord » Sat Dec 29, 2018 2:32 pm

I cleaned the tube leads but it doesn't seem to make any difference.

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