[TechAssist] Re: KV35S36 regs in thermal runaway
- From: "Leonard G. Caillouet" <lcaillo@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 22 Sep 2003 13:25:52 -0400
Tony,
Check the duty cycle, it should be pretty close to 50%. IF it is not, look
to one of the components in the primary or try matching your transistors. I
buy them in batches and they seem to match up pretty well but mixing batches
can get you in trouble, even with Sony replacements. Generics are fine if
they are the Shindingen parts and not some copy. I fix dozens of these
power supplies (using Tritronics generics made by Shindengen just like the
Sony pars) and never have a recall due to bad transistors. Check all of the
caps and diodes out of circuit. Check or replace VDR601, especially if R622
is open. I believe that one is a 430v rating.
Look to the secondary, like a problem in the 9v regulator. I just had one
kill Q601,2 that had a shorted SI3090C (IC641).
I also had one once with a bad T603. It rang good on all windings but I got
lucky and had one to compare it to that was reading differently. That was a
lightning damaged set and the only convertor that I have seen bad in a Sony
PS.
Does it fail if you run the PS unloaded out of the set?
Leonard G. Caillouet
Electronics World
Gainesville, FL
352-332-5608
352-332-5668 (fax)
----- Original Message -----
From: "tony saracco" <tcselectronics@xxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, September 22, 2003 12:11 PM
Subject: [TechAssist] KV35S36 regs in thermal runaway
I have changed the .47uf bird tird caps, .22uf blue caps, 2 - .001uf blue
caps ( basically all caps in primary side of reg circuit) statically check
all other reg components but Q 601 an 602 still over heat and die after 45
min. I even tried making heat sinks with no luck there. YES i am using
generic C4834's but can get away with it most of the time without thermal
probs. Have tried both P's and M versions.
any advise or maybe a pws part # if it is still available, Not listed on
tritronix model part list.
could use the SM if someone wants to Email it to me.
thanks much
Tony Saracco
TCS ELECTRONICS
Elgin , IL 60120
847-695-1928
tcselectronics@xxxxxxxxxxxxxxxx
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