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Old 09-04-2019, 08:33 PM   #1
geforcefly
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Default Recapping a Packard Bell PB1443CG CRT monitor

I recently got a Packard Bell CGA monitor from 1988 that let out the magic smoke and I want it to work again. Parts of the pictured board smell of bad electronics but I could not find anything burned. I originally thought it was the Samwha CE-W 220uf 250V 85C input cap, so I replaced it with a Panasonic equivalent (an EE series General Purpose 105C cap). The monitor let out more smoke (there would be no video at any time the monitor was on and it would smoke after about 10 seconds). So I decided to look at all the capacitors in the monitor. Other than one cap near the HOT section (circled in the attached picture) that I can't identify without very awkward removal, I was able to identify three different series of caps:
Samwha GA (all 160V)
Samwha SA (most of the large ones)
Chemi-Con SM (most of the smaller ones)

Quick searching wasn't coming up with much on the Samwhas, but the Chemi-Cons seems to be general purpose. I wouldn't think there would be any low-ESR caps in such an old monitor. So my plan is to recap the board full of Panasonic EE series caps (or equivalent).

Before I pull the trigger on buying the caps to fix the monitor, I would like a little input on if those caps are a good option or if something would be better. No matter what I will get 105C temperature-rated ones so that it will be reliable for many more years.
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Old 09-05-2019, 03:00 AM   #2
stj
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

power it up with the back open and a lamp in your hand to trace the smoke, or use your nose - it must smell of something.
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Old 09-05-2019, 04:58 PM   #3
geforcefly
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

I plugged it in, powered it on, and it didn't smoke. However, a high-pitched noise (which is equal to about 1/3 the monitor's normal scan rate of ~15.6KHz) can be heard.
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Old 09-05-2019, 05:44 PM   #4
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

Check for a shorted horizontal output transistor, it is likely mounted to the metal shield or heatsink around the flyback transformer. If it IS shorted, it could be that the smoke came from the flyback transformer itself.
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Old 09-05-2019, 06:53 PM   #5
geforcefly
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

I'll check it out later. Here's what it sounded like on power-on:
https://youtu.be/Ea2YURBEg_8
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Old 09-05-2019, 09:44 PM   #6
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

Quote:
Originally Posted by R_J View Post
Check for a shorted horizontal output transistor, it is likely mounted to the metal shield or heatsink around the flyback transformer. If it IS shorted, it could be that the smoke came from the flyback transformer itself.
That was going to be my suggestion as well. Horizontal circuits in old CRT monitors & televisions are typically the first things to go, even before power supplies.
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Old 09-05-2019, 09:49 PM   #7
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

After listening to the sound it makes, It sounds like the horizontal transistor is driving a bad flyback. Turn it on a couple times then (with the monitor off) feel the sides of the flyback transformer and if it is warm it is bad/shorted
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Old 09-07-2019, 10:36 PM   #8
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Default Re: Recapping a Packard Bell PB1443CG CRT monitor

Thanks for the suggestions. Definitely sounds like a bad flyback. Hopefully I can find one that will work with this 14" monitor. I believe that, along with the caps and a new HOT will restore this CRT to working order. An unfortunate break since there was no prior warning (no unusual artifacts in the picture; it was uniform, sharp, stable, and had good color).
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