I have a JVC 28" Television - its over 10 years old but still gives a good
picture most of the time.

My problem is that on an irregular basis the TV will appear to go into
standby (loss of picture and sound) and the power LED goes from bright to
dim.

A well aimed hard bash on the side will get it working again, sometimes for
a month, sometimes for a week or sometimes for a few minutes.

When it's working everyting is perfect so I'm assuming I have a dry joint or
loose connection rather than a faulty component.

Trouble is, when I take the back off it always works and I have been unable
to spot the problem area.

I'm good with electronics but don't know TVs that well. From my description
is there any particular area I should be looking (to narrow my search) or
could the fault lie anywhere.

Cheers,

Nigel

This type of fault can be difficult to find. It is probably a cold solder
(dry joint), or a defective connector, or a component that is mechanicaly
defective. These types of faults are difficult to find, even for the very
experienced.

The tech would prop the chasis up on its end, and carefully excersize the
various areas of the circuit boards to provoke the problem, in order to zero
in on it. The places to start looking are in the scan generator, power
supply, and scan amplifers. Start with areas where there are components that
run very hot.

When working on the TV set, take care for very serious safety issues. To
find this type of intermittant, the set will have to be operating to provoke
the fault. You may be best off to send it out for proper and safe service,
done by an experienced tech.



--

Jerry G.
=====



"Nigel Heather" wrote in message
...
I have a JVC 28" Television - its over 10 years old but still gives a good
picture most of the time.

My problem is that on an irregular basis the TV will appear to go into
standby (loss of picture and sound) and the power LED goes from bright to
dim.

A well aimed hard bash on the side will get it working again, sometimes
for
a month, sometimes for a week or sometimes for a few minutes.

When it's working everyting is perfect so I'm assuming I have a dry joint
or
loose connection rather than a faulty component.

Trouble is, when I take the back off it always works and I have been
unable
to spot the problem area.

I'm good with electronics but don't know TVs that well. From my
description
is there any particular area I should be looking (to narrow my search) or
could the fault lie anywhere.

Cheers,

Nigel

the areas you probably want to check are around the voltage regulator and
the standy circut i find that the regulator is usually close to where the
ac line goes in, before playing with a hot set i would drain everything
and flip the pcb over and go over with a magnifying glass when in doubt
resolder, then reseat all of the conectors and clean the as much dust out
of the set as you can. the only other part of the set that would throw it
into standby mode is the xray protection circut but since a gentle beating
will whip this tv into shape thats probly not the problem. but just incase
you can inspect the set for signs from electrical arcs around the flyback
and the "suction cup" on the top half of the picture tube

I found this site which lists some common faults with my set (AV28F1EK).
The first entry (intermittent loss of picture and sound) seem to be worth
following up.

Okay I know what a preset looks like but rather than try every one is there
anything that could help identify the Automatic Gain Control (for example is
it likely to be an IC). I assume that it won't be on the High Tension board
(is this correct?).

I'm loathed to take it to a TV repairer. Maybe I was unluckly but when I
tried this before with the set, the guy had it for 4 weeks and eventually
said that he couldn't find anything wrong and then tried to charge me £50
for the investigation. I refused of course but in the end I had to pay him
£20 to get the TV back off him.

Thanks again.

Cheers,

Nigel