Hi all,


I am writing from India and think you guys may help me. I
have a Sony 21" KV-K21MF1 TV set. The set has some
problems related to poor cable/antenna reception and
bad sound at times. There is a loud buzz in the TV and
sometimes the channels are in color and sometimes they
turn black and white. Normally on most of the channels
the reception is without color. When I change the
band, the picture comes colored, but the sound is
bad.


However, the TV works perfectly fine with VCD/DVD,
with full colors and oK sound. Sometimes the sound
gets distorted, and when it is switched on again it
gets good. However, after a couple of minutes, the
sound sometimes again gets distorted.


I took the TV to an Authorised Sony repair centre and they told me
that there is a problem with the IF board (block),
which is quite costly. What I gather from reading your
articles is that usually the problems are due to
improper soldering. Can u tell me whether this is the
case with my TV as well..


Looking forward to a help from you.


Thanks,
Nitin

Without taking your tv apart and checking the solder connections in the
IF block in your tv, I cannot say that this is the case with your tv or
not.

It was a common problem in the IF and tuners for Sony's made worldwide
between about 1987 and 1994, still is an occasional problem in the Sony
all in one Tuner/IF combo blocks today.

It is impossible to say what it is without going through it myself.

If there are any bad soldering connections, this will usually cause
intermittent faults, that would occur when tapping or pushing on the module,
or just simply moving the TV set.

These modules do go defective at time, and require to be replaced. Sometimes
if the fault is simple, they can be serviced. The service man would have to
have a way to run the module on some type of jig in order to troubleshoot
it. He would also have to have the proper test equipment to take
measurements of the various stages in it, in order to make proper evaluation
of it. This is usually not feasible.



--

Jerry G.
=====

"getfunky" wrote in message
oups.com...
Hi all,


I am writing from India and think you guys may help me. I
have a Sony 21" KV-K21MF1 TV set. The set has some
problems related to poor cable/antenna reception and
bad sound at times. There is a loud buzz in the TV and
sometimes the channels are in color and sometimes they
turn black and white. Normally on most of the channels
the reception is without color. When I change the
band, the picture comes colored, but the sound is
bad.


However, the TV works perfectly fine with VCD/DVD,
with full colors and oK sound. Sometimes the sound
gets distorted, and when it is switched on again it
gets good. However, after a couple of minutes, the
sound sometimes again gets distorted.


I took the TV to an Authorised Sony repair centre and they told me
that there is a problem with the IF board (block),
which is quite costly. What I gather from reading your
articles is that usually the problems are due to
improper soldering. Can u tell me whether this is the
case with my TV as well..


Looking forward to a help from you.


Thanks,
Nitin

That model does not sound familiar, but most of the Sony IF problems in the
sets with discrete IF blocks were just bad solder connections, though some
have a bad IC. Standard procedure for estimating these is to pull them and
look at the connections if the problem is isolated to the IF block. Either
way they are not expensive to repair. We usually keep one around from a
scrapper that is rebuilt and ready to go to save time.

Leonard

"getfunky" wrote in message
oups.com...
Hi all,


I am writing from India and think you guys may help me. I
have a Sony 21" KV-K21MF1 TV set. The set has some
problems related to poor cable/antenna reception and
bad sound at times. There is a loud buzz in the TV and
sometimes the channels are in color and sometimes they
turn black and white. Normally on most of the channels
the reception is without color. When I change the
band, the picture comes colored, but the sound is
bad.


However, the TV works perfectly fine with VCD/DVD,
with full colors and oK sound. Sometimes the sound
gets distorted, and when it is switched on again it
gets good. However, after a couple of minutes, the
sound sometimes again gets distorted.


I took the TV to an Authorised Sony repair centre and they told me
that there is a problem with the IF board (block),
which is quite costly. What I gather from reading your
articles is that usually the problems are due to
improper soldering. Can u tell me whether this is the
case with my TV as well..


Looking forward to a help from you.


Thanks,
Nitin

"Jerry G." writes:

It is impossible to say what it is without going through it myself.

If there are any bad soldering connections, this will usually cause
intermittent faults, that would occur when tapping or pushing on the module,
or just simply moving the TV set.

These modules do go defective at time, and require to be replaced. Sometimes
if the fault is simple, they can be serviced. The service man would have to
have a way to run the module on some type of jig in order to troubleshoot
it. He would also have to have the proper test equipment to take
measurements of the various stages in it, in order to make proper evaluation
of it. This is usually not feasible.



--

Jerry G.
=====

"getfunky" wrote in message
oups.com...
Hi all,


I am writing from India and think you guys may help me. I
have a Sony 21" KV-K21MF1 TV set. The set has some
problems related to poor cable/antenna reception and
bad sound at times. There is a loud buzz in the TV and
sometimes the channels are in color and sometimes they
turn black and white. Normally on most of the channels
the reception is without color. When I change the
band, the picture comes colored, but the sound is
bad.


However, the TV works perfectly fine with VCD/DVD,
with full colors and oK sound. Sometimes the sound
gets distorted, and when it is switched on again it
gets good. However, after a couple of minutes, the
sound sometimes again gets distorted.


I took the TV to an Authorised Sony repair centre and they told me
that there is a problem with the IF board (block),
which is quite costly. What I gather from reading your
articles is that usually the problems are due to
improper soldering. Can u tell me whether this is the
case with my TV as well..

Come on Jerry, hold off on the text book responses. You take it out, put
it under a strong light and magnefier if necessary to inspect, or just resolder
all the connections. Those who have done many of these know exactly which
pins tend to go bad.

If everyone followed your recommendations, the entire country would be
dark because light bulbs wouldn't get replaced without the proper light
bulb replacement tool. :-)

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
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