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Seeking part# for a Hitachi 27ax1b - C725

 
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kbaisley



Joined: 22 Aug 2007
Posts: 4

PostPosted: Wed Aug 22, 2007 1:28 am    Post subject: Seeking part# for a Hitachi 27ax1b - C725 Reply with quote

Hello Everyone,

I have a TV that has blown the C725 Ceramic Capacitor twice. 5 Years ago, shortly after a move from California to Illinois, my TV made that distinct buzz sound and would not power up. I am an amateure electronics hack who has fixed products in the past so I pulled off the cover..

Right next to a large cap in what looks to be a power circuit is the the postion marked with C725 and what looks to be a blue ceramic cap with the following markings ->hr r 222k 2KV CMID
I replaced that cap and the TV set worked for 5 years.. The same cap has burned out again. The store I bought the part from is now a parking lot and my search for a schematic has not been sucsessful yet.

Can anyone provide me the Hitachi part number or part number I can look up on digikey or somehwere ? I try to look up the spec.. but no luck.. again a newbie seeking help from the experienced.

I had a similar problem on a Sony set I had and I was able to get a kit that had several caps / resistors / mics that seem to be a common failure for the power circuit. I cannot find the same for this set.

Is there other parts you can recommend so that I fix this right versus just slapping in the cap ?

Thanks VERY MUCH for your help and patience with a hobbist

Regards,

Kevin
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Wed Aug 22, 2007 2:01 am    Post subject: Reply with quote

Kevin,
It's C724 your looking for but you're really not. Hitachi put out that your to remove and discard C724 if replacing Q711. This stabilizes Q907 your 9 volt regulator and allow B+ to reach IC201 sooner and keep Q711 from crapping out.
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kbaisley



Joined: 22 Aug 2007
Posts: 4

PostPosted: Wed Aug 22, 2007 2:13 am    Post subject: Reply with quote

I am looking at the board and its definitely C725. The capacitor is a blue ceramic and it actually blew this apart. The cap is directly behind the 4 wire plug.

I went to a TV shop before and swapped out just this single part and it lasted 5 years.. but did the same failure.. so something is worn causing this to fail (right rear corner of the circuit board ) Are you suggesting that I repalce Q711 ?

I need to find a schematic or a hitachi cross reference to cross these numbers into a part number or spec I can order from..

Should I move this to the other forum ? I placed in this one by mistake..

Thanks SOOO much for the help minnie !
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Wed Aug 22, 2007 2:25 am    Post subject: Reply with quote

I'll move it to equipment repair in the am and look for part #'s.
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PostPosted: Fri Aug 24, 2007 3:20 pm    Post subject: Reply with quote

you went from a dry climate to a wet one. every time you shut off your TV and it is hot it sucks cold wet air in and that is no good expecialy for large caps. what can you do well buy a pint of boiled lenseed oil and go for it paint your parts. My PC in the phillipines had the same problem after that paint job 10 years now no problem. actualy the USA goverment conformal coating is the best but where to buy ? it varnish is good also. OR LEAVE THE TV ON STAND BY. MOST OF NEW TV have that feature designed into it now.
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Fri Aug 24, 2007 3:28 pm    Post subject: Reply with quote

Huh? what .....painting your capacitors with linseed oil? lol

---that is a new one Rolling Eyes
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Fri Aug 24, 2007 9:38 pm    Post subject: Reply with quote

222k 2kv- 2200 pico fared @ 2000vdc. First 2 digits is value thirds the multiplier, 2 0's so 22 00 or 2200 @ 2kv 0r 2000 volts.
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