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Sony KV-36XBR400 no HV

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?
Reply to
James Sweet
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Known for Bad yokes... Also does this set have a splitter if so disconnect and try it.

Reply to
kip

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

Reply to
Leonard Caillouet

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.

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Jerry G.

1.7v but is instead 202(!)v. Any ideas on what to try next?
Reply to
Jerry G.

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.

Reply to
James Sweet

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.

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JANA _____

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.

Reply to
JANA

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

Le>> You will have to get the service manual, and use proper troubleshooting

Reply to
Leonard Caillouet

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

Reply to
kip

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

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

kip

Reply to
kip

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.

Reply to
James Sweet

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

Reply to
James Sweet

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

Reply to
Tom MacIntyre

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