Television Problem

[Chris]

I have a 9" Zenith television that has recently started to behave in an
unusual manner. Over approximately a one second time interval, both the
sound and the picture oscillate between being normal and having an extensive
amount of interference. The set is about 15 years old and probably not
worth having fixed. However, I'd be interested in fixing it myself if I can
determine the defective component. It must be either introducing or not
filtering a 60 hz signal. Any ideas?

Chris

p.s. The set is connected to a cable. I've tried various cable connection
points in our house, with no change in the symptoms. None of our other sets
are doing this.

 

[David]

Before even taking the set apart, make sure you have the tv set to the
correct cable mode for your area. If it is set to HRC or IRC it will
exhibit this symptom on many/most standard cable channels.

You are way off base in your assumption about a 60hz signal being
introduced. As a result you need to consider replacing it or having someone
with experience troubleshooting tuner/afc problems look at the set.

That particular set was designed to be module level replacement by Zenith,
as a result there is no way to actually work on the tv set in an operating
condition without the special jigs and set up required.

I would look for any obvious high ESR capacitors (15 years old, going to
have some), as well as failing solder connections (especially inside the
tuner module and the if circuits).

Without some standard tv troubleshooting information, there is no way to
direct you to the exact problem inside the set.

David

"Chris" <chrisw-lfp@comcast.net> wrote in message
news:80Sic.19747$0u6.3223085@attbi_s03...

I have a 9" Zenith television that has recently started to behave in an
unusual manner. Over approximately a one second time interval, both the
sound and the picture oscillate between being normal and having an
extensive
amount of interference. The set is about 15 years old and probably not
worth having fixed. However, I'd be interested in fixing it myself if I
can
determine the defective component. It must be either introducing or not
filtering a 60 hz signal. Any ideas?

Chris

p.s. The set is connected to a cable. I've tried various cable
connection
points in our house, with no change in the symptoms. None of our other
sets
are doing this.

 

[Chris]

David,

Thanks for your reply. It helped to resolve the problem. I got out the
manual again and manipulated the band selector and AFC settings until it
worked. With the band selector setting at catv, I toggled the AFC switch
from search to fixed. The problem went away. However, I later tried to
re-introduce the problem and wasn't able to. I suspect the set is near the
end of its useful life ...

The 60-hz thing was only a guess, just based upon how rapidly the
picture/sound was oscillating. It doesn't surprise me that I was off-base.

When I was young, I built a Heathkit AR-3 receiver. I learned how to read
resistors, how to solder, etc. It was great fun and provided a sense of
accomplishment. Because I was able to get it to work, I have a positive
attitude about being able to fix this set. However, based upon your
explanation of its modular design, it would probably be a difficult repair.

Again, thank you for taking the time to reply to my posting ...

Chris W.

Seattle, WA.

"David" <dkuhajda@locl.net.spam> wrote in message
news:408c0cb4@news.greennet.net...

Before even taking the set apart, make sure you have the tv set to the
correct cable mode for your area. If it is set to HRC or IRC it will
exhibit this symptom on many/most standard cable channels.

You are way off base in your assumption about a 60hz signal being
introduced. As a result you need to consider replacing it or having
someone
with experience troubleshooting tuner/afc problems look at the set.

That particular set was designed to be module level replacement by Zenith,
as a result there is no way to actually work on the tv set in an operating
condition without the special jigs and set up required.

I would look for any obvious high ESR capacitors (15 years old, going to
have some), as well as failing solder connections (especially inside the
tuner module and the if circuits).

Without some standard tv troubleshooting information, there is no way to
direct you to the exact problem inside the set.

David

"Chris" <chrisw-lfp@comcast.net> wrote in message
news:80Sic.19747$0u6.3223085@attbi_s03...
I have a 9" Zenith television that has recently started to behave in an
unusual manner. Over approximately a one second time interval, both the
sound and the picture oscillate between being normal and having an
extensive
amount of interference. The set is about 15 years old and probably not
worth having fixed. However, I'd be interested in fixing it myself if I
can
determine the defective component. It must be either introducing or not
filtering a 60 hz signal. Any ideas?

Chris

p.s. The set is connected to a cable. I've tried various cable
connection
points in our house, with no change in the symptoms. None of our other
sets
are doing this.