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From: hr(bob) hofmann on 29 Dec 2009 21:17
On Dec 29, 10:40 am, Andy Cuffe <acu...(a)gmail.com> wrote:
> On Sun, 27 Dec 2009 21:54:47 -0800 (PST), "hr(bob) hofm...(a)att.net"
>
> <hrhofm...(a)att.net> wrote:
> >Just had a Sony Model KV-1380R given to me a couple of days ago.  Only
> >problem is simultaneous but intermittent horizontal and vertical
> >shrinkage of about 20%, on a random basis.  Removed the set back,
> >problem is still intermittent, but appears to be less frequent.  Tried
> >beating on anything related to power supply, both in normal and
> >trouble modes, no effects.  I suspect something in the power supply
> >since both H & V are affected.  Currently running the set with a
> >voltmeter on B+ which is running about 155V, waiting for something to
> >go wrong.  But I can't sit around watching the set, just check it
> >intermittently.  Anyone had similar problems with this or similar
> >Sonys. Photofact folder is 2564, putting manufacture date at sometime
> >in 1987 or early 1988.  If anyone has a pdf of this folder, please let
> >me know.
>
> My money would be on the STRXXXX voltage regulator that most Sony's of
> that era had.  They are a common failure, although they usually do go
> intermittent.  
> Andy Cuffe
>
> acu...(a)gmail.com

Today the picture had shrunk when I went to my workshop. The
rectified line voltage had risen to 150 V from 140 V when the picture
was full-size. This might be due to a decreased load on the power
supply since the scanning current has gone down. Next thing to do
will be to see what if anything I can do about turning the set off and
on after a failure and see if the picture restores to correct size or
not. This seems to be a bottom-line Sony, so I don't know if there is
anything adjustable from a memory chip that might affect the picture.
I am also going to move my voltmeter to the CRT cap and see what the
HV does when the failure occurs. Stay tuned!

From: Chuck on 29 Dec 2009 23:10
On Tue, 29 Dec 2009 18:17:47 -0800 (PST), "hr(bob) hofmann(a)att.net"
<hrhofmann(a)att.net> wrote:

>On Dec 29, 10:40�am, Andy Cuffe <acu...(a)gmail.com> wrote:
>> On Sun, 27 Dec 2009 21:54:47 -0800 (PST), "hr(bob) hofm...(a)att.net"
>>
>> <hrhofm...(a)att.net> wrote:
>> >Just had a Sony Model KV-1380R given to me a couple of days ago. �Only
>> >problem is simultaneous but intermittent horizontal and vertical
>> >shrinkage of about 20%, on a random basis. �Removed the set back,
>> >problem is still intermittent, but appears to be less frequent. �Tried
>> >beating on anything related to power supply, both in normal and
>> >trouble modes, no effects. �I suspect something in the power supply
>> >since both H & V are affected. �Currently running the set with a
>> >voltmeter on B+ which is running about 155V, waiting for something to
>> >go wrong. �But I can't sit around watching the set, just check it
>> >intermittently. �Anyone had similar problems with this or similar
>> >Sonys. Photofact folder is 2564, putting manufacture date at sometime
>> >in 1987 or early 1988. �If anyone has a pdf of this folder, please let
>> >me know.
>>
>> My money would be on the STRXXXX voltage regulator that most Sony's of
>> that era had. �They are a common failure, although they usually do go
>> intermittent. �
>> Andy Cuffe
>>
>> acu...(a)gmail.com
>
>Today the picture had shrunk when I went to my workshop. The
>rectified line voltage had risen to 150 V from 140 V when the picture
>was full-size. This might be due to a decreased load on the power
>supply since the scanning current has gone down. Next thing to do
>will be to see what if anything I can do about turning the set off and
>on after a failure and see if the picture restores to correct size or
>not. This seems to be a bottom-line Sony, so I don't know if there is
>anything adjustable from a memory chip that might affect the picture.
>I am also going to move my voltmeter to the CRT cap and see what the
>HV does when the failure occurs. Stay tuned

This unit doesn't have adjustments stored in a EEprom. Mark
Zacharias' solution is the most common failure mode causing this
symptom. Rarely the STR IC goes intermittent and even rarer, a
resistor changes value in the regulator circuit. I'd replace the 33
uf cap he mentioned before further troubleshooting. Chuck
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