All,

my TV, a JVC AV-25F1EG, about 12 y.o. gave up recently. I guess it's the
high voltage that has blacked out.

After switching on, only sometimes for just a sec I hear sound and an image
pops up on screen. This image vanishes again, leaving a center glow on the
tube for just a sec. This being combined with obvious sounds coming from the
back of the TV (high freq tone that goes higher with time) makes me draw the
conclusion it's likely the high voltage.

Can anyone make a more educated guess from the described symptoms and shed
some light on if this is a repair one can do safely at home (security issues
re. high voltage).

I definately do not want to throw it away as I really LOVE its design and
overall performance.

Looking foreward to your info.

regards,
Michael

Going by your description, it seems that the protection circuits are
shutting the set down. This is because the high voltage, one of the scan
circuits may be out of specs, and or the one or more of the main power
supply outputs may be going too far out of specs.

The only way to start is to verify that the main supply is in specs, and
work from that point on. The first basic thing that tech will do is
measure the power supply outputs that feed the various areas, and
compare the readings to the service manual's information. If this is in
specs, then he will measure the outputs of the scan circuits, and also
test the high voltage.

To do this type of work, the proper tools and training would be
required. If the problem is a bit complex, the service manual will most
likely be required to follow through. There are also safety issues to be
respected when working on TV sets, or appliances.

I would suggest that you give the set out for an estimate, and then you
can make an intelligent decision if the set is worth to repair.
Considering that the set is 12 years old, many of the components are
aged, and there may be other unreliable factors.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
==============================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
==============================================
"blabla" wrote in message
...
All,

my TV, a JVC AV-25F1EG, about 12 y.o. gave up recently. I guess it's the
high voltage that has blacked out.

After switching on, only sometimes for just a sec I hear sound and an
image
pops up on screen. This image vanishes again, leaving a center glow on
the
tube for just a sec. This being combined with obvious sounds coming from
the
back of the TV (high freq tone that goes higher with time) makes me draw
the
conclusion it's likely the high voltage.

Can anyone make a more educated guess from the described symptoms and
shed
some light on if this is a repair one can do safely at home (security
issues
re. high voltage).

I definately do not want to throw it away as I really LOVE its design
and
overall performance.

Looking foreward to your info.

regards,
Michael

"Jerry G." schreef in bericht
...
Going by your description, it seems that the protection circuits are
shutting the set down. This is because the high voltage, one of the scan
circuits may be out of specs, and or the one or more of the main power
supply outputs may be going too far out of specs.

The only way to start is to verify that the main supply is in specs, and
work from that point on. The first basic thing that tech will do is
measure the power supply outputs that feed the various areas, and
compare the readings to the service manual's information. If this is in
specs, then he will measure the outputs of the scan circuits, and also
test the high voltage.

To do this type of work, the proper tools and training would be
required. If the problem is a bit complex, the service manual will most
likely be required to follow through. There are also safety issues to be
respected when working on TV sets, or appliances.

I would suggest that you give the set out for an estimate, and then you
can make an intelligent decision if the set is worth to repair.
Considering that the set is 12 years old, many of the components are
aged, and there may be other unreliable factors.

Thanks for your helpful comments.
It looks as if the TV is being shut down (at least most of the times)
allright.
The funny thing though, is that, once the TV runs (after numerous tries),
it's working perfectly for hours. So there might be a relation to the
initial currents that are going through the system at tv startup (from
stand-by)?
Anyway, due to lack of proper (secure)tools the best thing to do is indeed
bringing it in for an estimate.
Indeed it could be difficult to find spareparts for it, but I really LOVE
the looks and general performance (at least when it's working) of the
system.
**********************
HEY NOW.... WAIT !!!!!!
I just took the back of the TV (I'm a wiseguy anyway) and cleaned the inside
by blowing away all the dust inside. It was piling up on and around the
components in some static formation (like iron filings do when around a
magnet) and guess what: The TV is working flawless when switching on and
off.

Is it possible for dust to cause the described symptoms, or should I go and
have my own "magical breath" tv show? Has anyone any experience with dust
causing shortcircuiting?

Thx,
Michael

Bad solder on printed ciruit board
remove and resolder bad area,s
pull out you magnifier and throughly
check that board for bad ring joints.

kip

--
"

Yes ...
Check all the joints on the board as I suggest and reflow
the solder on anything that looks poor.


kip

--
"Watch the return E-Mail addy its false"
"blabla" wrote in message
...
"john" schreef in bericht
.. .
Bad solder on printed ciruit board
remove and resolder bad area,s
pull out you magnifier and throughly
check that board for bad ring joints.

kip

Thanks for your comments, however I don't think it's bad solder, 'cause
it's
never been soldered before (except in the factory).
Can solder go bad over time by the (over)heat(ing) of (individual)
components? If this is the case I might have to check the circuits indeed.