Sony KV-36XBR400 no HV

[James Sweet]

This set has a SCC-S47B chassis, odd symptoms in that when powered up
there is no HV, however when turned off the HV spikes to several KV for
just a moment as the thing is turning off. No diagnostic codes are
displayed on the LED and I've looked pretty closely on the deflection
board and retouched a bunch of solder joints but nothing has made a
difference yet. Looking at the HV driver IC I'm seeing 0 and 3.8V on
pins 1 and 2 respectively which should be 2.5 and 1.8v. Pin 7 has 0.1
but is listed as 4.0. Pin 12 is 0 but should be 4.6, pins 14-16 should
be around 160v but instead are sitting around 10v and pin 18 should be
1.7v but is instead 202(!)v. Any ideas on what to try next?

 

[kip]

Known for Bad yokes...
Also does this set have a splitter if so disconnect and try it.

kip

 

[Leonard Caillouet]

Known for Bad yokes...
Also does this set have a splitter if so disconnect and try it.

Bad yokes? Have not seen that. Sony told me to change a yoke on one once
but it did not fix the problem. Lots of intermittent and shutdown problems.
I would not recommend attacking this one without the service and training
manuals, as well as all of the tips from Sony ESI.

Leonard

 

[Jerry G.]

You will have to get the service manual, and use proper troubleshooting
methods to find this type of fault. In the past, but not always, I have
had the flyback, and a number of capacitors go defective in the
horizontal output section that causes this type of fault. Also, if there
is a vertical deflection failure, the horizontal output can go to the
protection mode, and therefore can do this type of fault. I have also
seen a defective CRT put the set in to the protection mode.

--

Jerry G.


This set has a SCC-S47B chassis, odd symptoms in that when powered up
there is no HV, however when turned off the HV spikes to several KV for
just a moment as the thing is turning off. No diagnostic codes are
displayed on the LED and I've looked pretty closely on the deflection
board and retouched a bunch of solder joints but nothing has made a
difference yet. Looking at the HV driver IC I'm seeing 0 and 3.8V on
pins 1 and 2 respectively which should be 2.5 and 1.8v. Pin 7 has 0.1
but is listed as 4.0. Pin 12 is 0 but should be 4.6, pins 14-16 should
be around 160v but instead are sitting around 10v and pin 18 should be
1.7v but is instead 202(!)v. Any ideas on what to try next?

 

[James Sweet]

You will have to get the service manual, and use proper troubleshooting
methods to find this type of fault. In the past, but not always, I have
had the flyback, and a number of capacitors go defective in the
horizontal output section that causes this type of fault. Also, if there
is a vertical deflection failure, the horizontal output can go to the
protection mode, and therefore can do this type of fault. I have also
seen a defective CRT put the set in to the protection mode.

I have the service manual, hence knowing what voltages should appear but
I haven't been able to track down the source yet. Vertical deflection
failure will trigger a full shutdown with fault code supposedly, the set
doesn't shut down, it'll run all day with sound but no picture,
something is preventing the HV from coming up.

 

[JANA]

Try removing the CRT socket board from the tube. Turn on the power, and see
if the HV comes on and stays up. If so, the CRT has a short in it, or it is
very far over-biased. I found that most of the time, it is the CRT in this
case.

--

JANA
_____

You will have to get the service manual, and use proper troubleshooting
methods to find this type of fault. In the past, but not always, I have
had the flyback, and a number of capacitors go defective in the
horizontal output section that causes this type of fault. Also, if there
is a vertical deflection failure, the horizontal output can go to the
protection mode, and therefore can do this type of fault. I have also
seen a defective CRT put the set in to the protection mode.

I have the service manual, hence knowing what voltages should appear but
I haven't been able to track down the source yet. Vertical deflection
failure will trigger a full shutdown with fault code supposedly, the set
doesn't shut down, it'll run all day with sound but no picture,
something is preventing the HV from coming up.

 

[Leonard Caillouet]

Do you have the training literature? I find that to be as useful as the
service manual on these sets.

Leonard

 

[kip]

Yes very common on that Model...Mainly Horizontal troubles.
kip

 

[kip]

Check or change those parts,try heating the IC first.

IC8002 (MCZ3001D) , C8024, C8024, C8031,C8033 .


kip

 

[James Sweet]

Do you have the training literature? I find that to be as useful as the
service manual on these sets.

Unfortunately no, I'll try pulling the neck board next time I'm out
there though, shorted CRT would at least be a nice easy explanation.

 

[James Sweet]

Yes very common on that Model...Mainly Horizontal troubles.
kip

What's the usual symptom of a bad yoke? If I ring it with a flyback
tester will it likely show as bad?

 

[Tom MacIntyre]

What's the usual symptom of a bad yoke? If I ring it with a flyback
tester will it likely show as bad?

It's been awhile, but other than ringing and swapping, I don't recall
any sort of recognizable and specific symptom of a bad yoke. I have
seen one situation at least where the yoke rang okay and was bad, but
I don't personally ever recall the reverse scenario.

Tom