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 Post subject: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Wed 16, 2019 6:27 am 
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Location: Omak,wa,usa
Hello Guys,
My Sony model KV27XBR10 stopped working the second time in its 29 years of service.

Anyway A couple caps went bad on the switching power supply board here is a photo of it and one the caps a 1000ufd at 16 volt which decided to leak fluid on the board causing some concerns where got to clean up the acid from the cap and re- solder .

Far as Clean up what are you guys using? I am using Alcohol and q-tips .

First, I decided I will just go ahead and replace all electrolytic caps on the board the two pricey ones are 1000 ufd at 160 and 200 volt the rest are cheap


Far as the Electrolytic caps go I figure low ERS like these [url]file:///C:/sony%20tv/SLP-15028.pdf[/url]
Here is a photo of the cap and my board nd the bad cap notice the writing is almost gone you see it faintly .


Sincerely Rich


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powersupply board .jpg
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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Wed 16, 2019 12:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: dayton oh usa
entry level low esr like panasonics fc series on the output.
the big cap on the output should also be chosen for low esr as well.
wont hurt to go up a step in voltage or capacitance on it either.
the replacements will be smaller so its easier to upsize to get the size close on those big snap in cans.
105 degree stuff or better.
i remember rebuilding plenty of those boards when the sets hit around 3 years.
those caps could not take the ripple and died early.
if you got it in at the "everything has jagged edges" stage a recap would fix it.
but many ran till the overshot and killed the hot and caused a cascade failure in the power supply.
the choppers were special and too many of the ones on the market were counterfeit.
this means it might work a few seconds to a few weeks and go bang again!


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Wed 16, 2019 2:39 pm 
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Location: Norfolk, VA
If you do go with the Panasonic FC series (a WISE choice!!), always opt for the longest version of the cap. A 1000uF 16V FC series cap comes in several sizes, with the "S" suffix being the short version which has lower ripple current than the long version, that is usually 5mm longer. For singles-9 quantity, I go to Talon, for >10, I usually go to DigiKey - they are good with FIFO, so fresh stuff there. I've only bought Nichicons and the occasional United Chemicon at Mouser - I get Panasonics at DigiKey, to take advantage of their free shipping with prepaid order scheme.

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Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Sun 20, 2019 10:36 pm 
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Hello guys,
today is order day for me far as the caps go .

Sincerely Rich


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Sun 20, 2019 10:46 pm 
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As far as cleaning the board, the last time I had to do that I used water and dish washing detergent. The chemicals in the cap are dissolved in water. You can use alcohol to remove the water or just wait long enough.

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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 21, 2019 4:59 am 
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Hello tom,
I did not see a acid mainly the effects


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 21, 2019 5:06 am 
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Joined: Apr Sun 15, 2012 3:10 pm
Posts: 1016
Location: Buffalo, NY
Tom Schulz wrote:
As far as cleaning the board, the last time I had to do that I used water and dish washing detergent. The chemicals in the cap are dissolved in water. You can use alcohol to remove the water or just wait long enough.

Yeah when I used to work on TV main boards of this vintage, I would just run them under the faucet with hot/warm water and that was enough to clean up nicey nice. After that treatment I'd hit em with the hair dryer on Low. Of course that was just a board as found without any damage from blown up capacitors.
More often than not, they were so sifty with dust, etc I wasn't gonna even try to work on them until cleaned up. From the PIC yours doesn't look too nasty from here...


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 21, 2019 12:59 pm 
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Hello Tom,
yes I once had to take a vcr apart and clean that way the owners kid decided to put a popsicle in the machine .

Sincerely rich


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 21, 2019 11:54 pm 
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Location: Buffalo, NY
LOL, I once pulled a stale peanut butter and jelly sandwich out of my sister's VCR.


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Tue 22, 2019 1:18 pm 
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Hello Tom,
that's funny another time I had help rescue a expensive Panasonic professional vcr used by a high school football couch the kids poured paint into the machine.

Sincerely Rich


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 28, 2019 1:30 am 
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Hello Guys,
I replaced All of the electrolytic caps on the board also cleaned it and soldered everything but still no go.
you don't even hear the main relay energize when you hit the power button.
Sure, glad that I have the factory service manual to trouble shoot it.
Well most of the resistors have been checked and see if they were good and yep, they are next I’ll check to make sure there no open paths in the traces.
There are transistors and diodes also regulators to check but,

I am guessing the Main regulator is gone bad it’s a STR-S6301A and I see eBay has some for sale.

Any ideas or suggestions where to check next.
Sincerely Rich


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 28, 2019 1:44 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: dayton oh usa
check your standby supply.
the blue/white transformer and its associated components.


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 28, 2019 1:59 am 
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hello kc8adu,
sounds good thanks


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 28, 2019 5:08 am 
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Hello kc8adu,
I checked the power transformer and switching transistor for the relay also the relay it looks good I will use my powersupply to power that circuit up with out using the tv just to see if I cant switch the relay


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 Post subject: Re: Repairing My Sony 1990 XBR tv second time in 29 years .
PostPosted: Oct Mon 28, 2019 1:14 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: dayton oh usa
isolation transformer mandatory if you are going to attach anything.
its hot chassis.


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