Sony model #HT32744. Hit power button, relay clicks, high voltage
starts up, then relay clicks a few times and no go. Checked bridge
rectifier, shows voltage while starting up, but goes to nothing when
relays click. Had disconnected power to HV board before, and after I
did this. No difference. I don't have a schematic, and have no info on
this particular model #, besides having only about 2-3 years
experience. I'm aware several things could cause this, but without a
service manual, I'm shooting in the dark. Looking for a little advice
on this set as well. Thank you to all replies.

On May 30, 5:36 pm, Golf wrote:
Sony model #HT32744. Hit power button, relay clicks, high voltage
starts up, then relay clicks a few times and no go. Checked bridge
rectifier, shows voltage while starting up, but goes to nothing when
relays click. Had disconnected power to HV board before, and after I
did this. No difference. I don't have a schematic, and have no info on
this particular model #, besides having only about 2-3 years
experience. I'm aware several things could cause this, but without a
service manual, I'm shooting in the dark. Looking for a little advice
on this set as well. Thank you to all replies.

Forgot to mention, I checked all diodes, resistors in the power
supply. Not sure how to check the voltage regulator though. Thanks.

Also forgot to mention, this isn't a Sony. It's a Sanyo. Too many sets
on the bench!. Thanks group.

Thanks for reply Jamie. The flyback does tick during start up, but I'm
not sure if this is normal or not. I haven't tried ringing the
windings or anything yet.

Golf wrote:

Sony model #HT32744. Hit power button, relay clicks, high voltage
starts up, then relay clicks a few times and no go. Checked bridge
rectifier, shows voltage while starting up, but goes to nothing when
relays click. Had disconnected power to HV board before, and after I
did this. No difference. I don't have a schematic, and have no info on
this particular model #, besides having only about 2-3 years
experience. I'm aware several things could cause this, but without a
service manual, I'm shooting in the dark. Looking for a little advice
on this set as well. Thank you to all replies.

HV supply is bad? (FLyBack)? or maybe the HV-TRAnsistor?


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Golf wrote:

Thanks for reply Jamie. The flyback does tick during start up, but I'm
not sure if this is normal or not. I haven't tried ringing the
windings or anything yet.

also, many units derive low voltage from the flyback when it's
fired up. I have found in some cases where this voltage gets
rectified, the filter caps are bad.. and other times, devices
connected to this source are shorted..
the main PS unit also may monitor this source to know when to
shut down the unit if voltage is gone or never gets there after
a couple of sec's


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

also, many units derive low voltage from the flyback when it's
fired up. I have found in some cases where this voltage gets
rectified, the filter caps are bad.. and other times, devices
connected to this source are shorted..
the main PS unit also may monitor this source to know when to
shut down the unit if voltage is gone or never gets there after
a couple of sec's

Thanks again. Iv'e checked every cap in the PS and all good. I'm sure
the main PS isn't the problem. Iv'e also checked several other
electrolytics, and nothing yet. Again, without a manual or schematic,
I can only check each component as I go. This may be beyond my
capability, but I'll reply after the flyback test - even though I was
told by a tech this can give false results. Thanks again.

I can hear it, and feel the static electricity build on the screen.
But it doesn't stay up long enough to show any raster - only a sec. or
two. Thanks for the reply. Any suggested checks much appreciated meat.
You have helped me before.

On May 30, 8:32 pm, Meat Plow wrote:
On Wed, 30 May 2007 19:08:35 -0700, Golf wrote:
I can hear it, and feel the static electricity build on the screen.
But it doesn't stay up long enough to show any raster - only a sec. or
two. Thanks for the reply. Any suggested checks much appreciated meat.
You have helped me before.

Sounds like it could be going into X-Ray protection. It will do that if
the HV goes to high if the tuning in the HV circuit is incorrect. I don't
recall how old the set is but I used to work on plenty of them in the
80's and I doubt they got rid of that circuit. There are a couple caps
in that circuit that provide tuning along with other devices. Sets that
acted like this I would ramp up on a variable supply and monitor the
voltage at the anode to troubleshoot it. That's about the extent of my
help however right or wrong it turns out to be

Thanks Meat. Again, this is a SANYO. I f'd up in the original post
saying it was a Sony. This set is only 3 years old. I agree that it
may be a protection circuit shutting it down, and I do have a variable
supply that I can try, and go from there. Thanks for the info.

You need a HV probe for the anode. Start it out around 60 volts and see if
it fires. If not jump up 5 volts until you get it to start. Look at the
HV, if it goes above 25KV it should shut down. Have fun and watch those
lethal voltages. Let me know what you find. Watch the chassis too because
most of them are above ground around 200 volts. Don't be brave

OK, I managed to get the set to stay on around 70V on the variable.
The high voltage stayed up but the flyback was still ticking. Anode
checked 18KV and was stable. Set shut down around 80V on variable.
Checked the raster while HV was up, and saw a faint glow in the middle
of the set (about 1" square) that pulsed with the flyback ticking. If
I vary the voltage below or above 70V, the relays in the PS start
clicking like crazy. I suppose the flyback could be bad even though
the HV is stable?

On May 31, 12:01 pm, Meat Plow wrote:
On Thu, 31 May 2007 09:55:55 -0700, Golf wrote:

You need a HV probe for the anode. Start it out around 60 volts and see if
it fires. If not jump up 5 volts until you get it to start. Look at the
HV, if it goes above 25KV it should shut down. Have fun and watch those
lethal voltages. Let me know what you find. Watch the chassis too because
most of them are above ground around 200 volts. Don't be brave

OK, I managed to get the set to stay on around 70V on the variable.
The high voltage stayed up but the flyback was still ticking. Anode
checked 18KV and was stable. Set shut down around 80V on variable.
Checked the raster while HV was up, and saw a faint glow in the middle
of the set (about 1" square) that pulsed with the flyback ticking. If
I vary the voltage below or above 70V, the relays in the PS start
clicking like crazy. I suppose the flyback could be bad even though
the HV is stable?

Unless there was a common problem with flybacks on this chassis I would
not include it on my possible list. That's one problem I have being out of
the loop and not knowing these things. When the set does shut down at 80
what was the HV? You might want to get your wallet out and snag some
service literature and check some voltages. Also you could look for some
cold solder joints in the SMPS and HV block/flyback before you spend money
because I've read about issues with newer sets and lead-free solder.

Thanks. I am now looking in the SMPS. Trying to find info on the
switching IC to see if I can determine if it may be a problem. I
already checked all componenets in this area. Haven't checked solder
joints yet. BTW - the HV was steady 18KV when the set shut down.

Sony model #HT32744.

Shucks! I thought this was an announcement that Sony, USA had closed its
doors...
--
Al, the usual