Monitor recapping and low ESR

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sandord
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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 7:23 pm

exxos wrote:
Fri Oct 26, 2018 7:18 pm
Some caps "back in the day" were the size of coke cans, replacements like 5% of the size...

bi-polar caps though ? Wonder why... I probably would have just stuck a polyester in it instead :)
Well, let's just try it then. Looks a bit lonely though, such a small cap in such a big place (the circle on the PCB is as large as my thumb).

I have absolutely no idea why bi-polar, the 1084-D2 I recapped yesterday didn't have one but the design was quite different as well. Different manufacturer I think, lots of signs of that (different par number encoding schema, different pcb symbol style etc.)

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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 7:27 pm

Looks really lonely... please don't explode :x

IMG_20181026_202417.jpg
IMG_20181026_202417.jpg (139.84 KiB) Viewed 982 times

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Re: Monitor recapping and low ESR

Post by exxos » Fri Oct 26, 2018 7:34 pm

sandord wrote:
Fri Oct 26, 2018 7:27 pm
Looks really lonely... please don't explode :x
:lolbig: :bravo:
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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 10:24 pm

YIKES!

I just finished recapping the 1084S-P2 and powered it on. Perfect picture! Ultimate stability!

And then...

I heard a popping/hissing sound :shock: :o :cry:

I rushed to pull the plug (the powerbutton is broken as usual with these devices).

The funny thing is that I didn't smell anything odd, which usually is the case when something is burning. A quick inspection didn't reveal anything suspucious. Neither any smoke was visible.

The one thing that crosses my mind is the suction cap that connects the tube to the line transformer, I had a little trouble reconnecting it properly. Though the leads are in the tube hole, the suction cap my be just a little not-so-tightly-connected. Could it be that I heard sparks from underneath there?

Obviously I checked the bipolar cap but it looks okay. I haven't measured anything yet, not even sure how to do that.

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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 10:36 pm

Some more observations:

- the picture didn't turn bad or anything when I heard the sound
- a cable with an interference suppressor on it * MIGHT * have touched some parts on the pcb, so perhaps that was shorting something
- I'm afraid to turn it on again :roll:

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Re: Monitor recapping and low ESR

Post by exxos » Fri Oct 26, 2018 10:44 pm

sandord wrote:
Fri Oct 26, 2018 10:24 pm
The one thing that crosses my mind is the suction cap that connects the tube to the line transformer, I had a little trouble reconnecting it properly. Though the leads are in the tube hole, the suction cap my be just a little not-so-tightly-connected. Could it be that I heard sparks from underneath there?
You can lift the cap up with a screwdriver (BUT insulated handle as it could be charged to like 30KV!) and check its inserted correctly. We use to wire a screwdriver to the gnd strap and poke under the cap to discharge it before checking or removal.
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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 10:49 pm

exxos wrote:
Fri Oct 26, 2018 10:44 pm
You can lift the cap up with a screwdriver (BUT insulated handle as it could be charged to like 30KV!) and check its inserted correctly. We use to wire a screwdriver to the gnd strap and poke under the cap to discharge it before checking or removal.
I've rocked the cap with a well insulated heavy plier and I'm sure it's connected firmly.

Perhaps I should just turn it on for a few more seconds and see if I can see anything if the sound comes back. Hopefully not a spark :shock:

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Re: Monitor recapping and low ESR

Post by exxos » Fri Oct 26, 2018 10:58 pm

sandord wrote:
Fri Oct 26, 2018 10:49 pm
I've rocked the cap with a well insulated heavy plier and I'm sure it's connected firmly.

Perhaps I should just turn it on for a few more seconds and see if I can see anything if the sound comes back. Hopefully not a spark :shock:
If you can turn on via extension cable, and look at the rear and power up, you can see in almost dark if anything is arcing inside or not.
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Re: Monitor recapping and low ESR

Post by sandord » Fri Oct 26, 2018 11:11 pm

exxos wrote:
Fri Oct 26, 2018 10:58 pm
If you can turn on via extension cable, and look at the rear and power up, you can see in almost dark if anything is arcing inside or not.
Good advice!

I just did that. The monitor has been running for minutes now and nothing seems wrong. So it must have been the inteference suppressor causing a short on the PCB. I tied it up higher to avoid that from happening again.

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Re: Monitor recapping and low ESR

Post by exxos » Fri Oct 26, 2018 11:15 pm

Could be be a "singing inductor" ? Those things can hiss/squeal and make a right row...
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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