[TechAssist] Re: Sony KV27FS100L
- From: Paul <dntwntv@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 3 Oct 2005 10:49:44 -0700 (PDT)
Russ
That is an interesting situation. Do you remember if the power supply in the
Sony had two switching mosfets or not?
Paul
Hoyt's TV <hoytstv@xxxxxxxxxxx> wrote:
Paul, Try disconnecting the anode lead and see if it will run.
I had a KV24FS100 that I repaired the power supply and replaced the HOT and
it would then fire up to a lower than normal HV for a few seconds and go
into shutdown. After a conversation with the Sony Tech at Fultons and doing
the testing he recommended, we decided it needed a HO Transformer even
though it rang OK.
I put that in and it still did the same thing. That's where the customer
said "uncle" and I quit working on it.
A few weeks later I got in a JVC (I think) that was doing the same thing but
the power supply was OK. The H wave forms looked exactly the same as what
the Sony tech said indicated a bad IHVT. The two transformers appeared to be
identical so I put in the new Sony one and got the same results.
For some reason I decided to hook the chassis up to my test jig to see what
would happen. It worked fine on the test jig. I plugged the factory yoke
back in and it still worked fine and stayed on, without any vertical
deflection on the test jig of course. But when I hooked it back up to it's
own CRT it went into shutdown. I unhooked the anode lead and it kept
running. So there must have been an anode short in the CRT.
I never tried the Sony again to see if it had an anode short because I had
removed all the power supply and HV parts when I quit working on it.
Russ Hoyt
Hoyt's TV
Exeter, NH
----- Original Message -----
From: "Paul"
To:
Sent: Friday, September 30, 2005 2:27 PM
Subject: [TechAssist] Re: Sony KV27FS100L
>I don't think the vertical I/C that I replaced was bad. The problem seems
>to be that the B+ never gets up to 135v. It makes about 47v then shuts down
>and goes into standby. I found a dual diode that was shorted in the
>secondary but it supplies the audio amp and removing it did not make any
>difference in the low B+ problem. Unless the secondary needs an exact load
>in order to run, I am at a loss to know what is going on.
> Paul
> Wayne Vanaman wrote:
> I have seen a number of sets that, when the vertical IC fails it takes
> out the video processor. Check for vertical drive out of the processor.
> Pins 28 and 29. These are complimentary sawtooth waveforms, about
> 1.2v pk-pk.
>
> Wayne Vanaman
> Omega Electronics
> 6904 W Fairfield Dr
> Pensacola, Fl. 32506-3310
>
> Wayne@xxxxxxxxxxxxxxxxxxxxx
> WWW.PensacolaTVRepair.Com
>
> 850-456-5995 voice
> 850-458-6369 fax
>
>
> Leonard Caillouet wrote:
>> Four blinks can be either vertical or horizontal or something else that
>> causes the vertical output to not work.
>>
>> Leonard Caillouet
>> Service Manager
>> Electronics World
>> Gainesville, FL
>>
>> ----- Original Message -----
>> From: "Paul"
>> To:
>> Sent: Thursday, September 29, 2005 8:39 PM
>> Subject: [TechAssist] Sony KV27FS100L
>>
>>
>> How reliable are blink codes? This set is becoming more of a problem than
>> I
>> first thought. The blink code is four, indicating a problem in the
>> vertical
>> circuit, as I suspected before getting the service manual. I replaced the
>> vertical I/C as the most likely cause per the self diagnostics. Problem
>> remains, that being the set tries to start but never makes enough B+ and
>> goes into stand by. I removed the HOT and replaced both switching
>> mosfets.
>> Nothing has changed. I have checked the lytics in that circuit, and
>> supply
>> resistors. Nothing shorted or low to ground on the B+ line.Haven't found
>> anything bad yet. When I took the back off and saw that the chassis was
>> the
>> one that has bad tact switches I headed there first. Anyone familiar with
>> this chassis and this problem?
>> Paul
>>
>>
>> Paul ,B
>> Central TV&Video
>> 911W Grand Ave
>> Grover Beach Ca.
>> (805)481-8084
>>
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> Paul ,B
> Central TV&Video
> 911W Grand Ave
> Grover Beach Ca.
> (805)481-8084
>
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Paul ,B
Central TV&Video
911W Grand Ave
Grover Beach Ca.
(805)481-8084
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