Author Topic: Reparing TV PSU  (Read 2550 times)

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Offline PhaedrusTopic starter

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Reparing TV PSU
« on: January 06, 2014, 09:33:13 pm »
Pretty easy project, really, just repairing the PSU in a dead Samsung TV in the hopes of making it work again.

There are some blown caps on the secondary of course, so I'm replacing all of the electrolytics except the 450V primary cap (since it's expensive and probably ok) with 105C Japanese caps.

However, I also found a dead bug that managed to short across two leads of the bridge rectifier (TS4B05G). I tested the diodes with my meter and it tests fine, as well as the PFC fets, but I was wondering if that short might have damaged other nearby components, or the PFC control circuit. Is this likely, and is there any easy way to check?
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Offline bgsteiner

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Re: Reparing TV PSU
« Reply #1 on: January 07, 2014, 03:21:23 am »
any IC's could have gone as well with a dead short like that i would look for any charing or bulging of components or cracks in any IC's
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Offline PhaedrusTopic starter

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Re: Reparing TV PSU
« Reply #2 on: January 13, 2014, 11:26:47 pm »
Caps arrived.

5x Nichicon 1000uF 25V
5x Panasonic 2200uF 10V
10x Rubycon 47uF 50V
10x Rubycon 10uF 50V

All 105C of course. Even if they don't fix the TV, they're still good, useful caps. :)
"More quotes have been misattributed to Albert Einstein than to any other famous person."
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Offline PhaedrusTopic starter

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Re: Reparing TV PSU
« Reply #3 on: January 14, 2014, 02:56:13 am »
Like magic, good as new. But now he wants me to fix his microwave  ::)
"More quotes have been misattributed to Albert Einstein than to any other famous person."
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Offline richard.cs

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Re: Reparing TV PSU
« Reply #4 on: January 14, 2014, 10:07:16 am »
Like magic, good as new. But now he wants me to fix his microwave  ::)
Good news :) Microwaves are pretty easy to fix (assuming you're serious), I've done loads. A couple of tips: that HV capacitor is deadly, it's almost always the door interlocks that fail.

Probably shouldn't go into any more details without starting a new thread.

 

Offline SeanB

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Re: Reparing TV PSU
« Reply #5 on: January 14, 2014, 06:08:28 pm »
Common faults I see on microwaves are door switches ( fuse blows violently), replace all 3 if you are suspecting them. Also common is the HV diode failing. Symptom is HV fuse blowing along with the LV fuse. Also common is an open circuit capacitor which does not blow fuses but the microwave only heats up slowly.

Common is a dying magnetron if cap and diode is fine but low heating. Check as well the fan actually works and blows air and the covers that direct air into the magnetron for cooling are still there so it cools. A blowing oven lamp can pop the fuse as well with no other symptoms other than the light going out, new fuse fixes microwave.

Keep a can of roach killer nearby when opening them, they are the perfect breeding place.
 

Offline PhaedrusTopic starter

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Re: Reparing TV PSU
« Reply #6 on: January 15, 2014, 01:25:22 am »
Heh, he does have a dead microwave, but the part about him asking me to fix it was a joke. I might take a look at it though, so thanks for the advice!
"More quotes have been misattributed to Albert Einstein than to any other famous person."
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