Sony KV20TS32 no pic -- good sound

Guest
Hi. Got a Sony KV20TS32 here. Good sound, HV present. Good vertical from
vert chip and horiz going to HOT, going by scope. Red led flashes.
Checked/touched up bad solder joints. When turned off, shows flash of raster
as it goes down. Haven't check HV level yet with the HV probe. Just seeing
if you have seen this before.

Cheers, Danny
 
Troubleshoot for a weak crt. The AKB circuit is probably blanking the video
due to a dud crt. Check the newsgroup archives for lots of posting about
the Sony video blanking problems.
David

<djnoble35209@charter.net> wrote in message
news:100bp7uke12ft0e@corp.supernews.com...
Hi. Got a Sony KV20TS32 here. Good sound, HV present. Good vertical from
vert chip and horiz going to HOT, going by scope. Red led flashes.
Checked/touched up bad solder joints. When turned off, shows flash of
raster
as it goes down. Haven't check HV level yet with the HV probe. Just seeing
if you have seen this before.

Cheers, Danny
 
If you are describing red flashes in the picture, this is most probably from
the CRT being defective. This is common on many sets using the Aperture
grill type tube.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


<djnoble35209@charter.net> wrote in message
news:100bp7uke12ft0e@corp.supernews.com...
Hi. Got a Sony KV20TS32 here. Good sound, HV present. Good vertical from
vert chip and horiz going to HOT, going by scope. Red led flashes.
Checked/touched up bad solder joints. When turned off, shows flash of raster
as it goes down. Haven't check HV level yet with the HV probe. Just seeing
if you have seen this before.

Cheers, Danny
 
Thanks for the replies on it. I messed with some more this evening, and
noted something. I turned the screen control up and video came up instantly,
not gradually. If pushed far enough, retrace lines become visible as usual.
Turn it down enough, video drops instantly. I scope video going up to crt
board to see it. If reduced to a point, video instantly vanised, just
leaving the frame with timing spikes. Turn screen up some, instant video and
it looks fine. I haven't seen this action before, usually is a gradual
thing.

Cheers, Danny
 
You must have never repaired a Sony tv set with a weak crt and the famous
AKB circuit before.

The only thing you need to do to confirm a weak tube is to take your dual
channel o'scope. Sync on channel B with it hooked up to the horizontal sync
pulse, you can use vertical pulse if the scope has a good delay sweep
feature. Place the A channel on the AKB return line. With the tv set from
an OFF position for more than 30 minutes (the tube guns must be cold), turn
on the tv and monitor the AKB return pulses. There will be three of them
close together, R G B. Look for one of the pulses that rises significantly
faster than the other two or lags behind the other two and rises very
slowly. If one gun is way out of balance or all three rise very slowly,
the tube is weak and the permanent fix is to replace the tube.

David

<djnoble35209@charter.net> wrote in message
news:100ebe98vc3oqa9@corp.supernews.com...
Thanks for the replies on it. I messed with some more this evening, and
noted something. I turned the screen control up and video came up
instantly,
not gradually. If pushed far enough, retrace lines become visible as
usual.
Turn it down enough, video drops instantly. I scope video going up to crt
board to see it. If reduced to a point, video instantly vanised, just
leaving the frame with timing spikes. Turn screen up some, instant video
and
it looks fine. I haven't seen this action before, usually is a gradual
thing.

Cheers, Danny
 

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