Sony KP-46WT520 Picture Problem

[SOPHM]

When turned on there's sound but no picture within 10 seconds or so it shutdown and standby blinks 10times.

If left off awhile and turned on 1st time you might get picture if not then few time on and off get it.

If left unplugged for awhile then turn it on you get picture on first try.

Either way when you have picture and turn it off you wont get picture till it sits off or unplugged.

I know the parts you should change with the 10blink code that's service manual say, But if i can still get picture they might be working or they might be having Intermittent problems.

HV Protection 10 times 10:0 or 10:1
• Q8014 or Q8013 have shorted replace along with R8051 on D Board
• IC8005 is damaged (D Board)
• No picture
Q8014/Q8013 TRANSISTOR 2SK3568 No idea how to test with DMM
R8051 FUSIBLE 0.1 10% 1/2W Check and was in tolerance range
IC8005 IC TL1431CZ-AP No idea how to test with DMM

So what do any of you's think.. Thanks for any info

[SOPHM]

I must have TV's with problems no one seen or heard of before.

[Justmanuals]

This Parts & Service manual can now be purchased for $11.77 and downloaded immediately after payment from:

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[SOPHM]

[vtech]

Not familiar with the specific set but can give you the following info;
In general, power Mosfets either work or when failure occurs, it shorts out all the way around and very rarely open or become intermittent. However, when it fails, it will almost always result in a blown fuse or some sort of a circuit protector. You may utilize a DMM to check for shorts between the pins. (preferably out of the circuit)
There is no 100% way of reliable testing of a Mosfet with DMM but as GO/NO GO test, there should be low or very-low resistance between drain-source on either direction and rather high resistance between Gate to source or Gate to drain. (it can get confusing if/when there is a built in diode between any of the pins though as I think that's what you have?). Once damaged, it can never work again. So if at any time, you can see an operational circuit, it is more than likely OK.
On the other hand the "1431" reference regulator IC which comes in various suffixes, is a rather sensitive device and since it is used in the feedback circuitry in SMPS circuit, can easily cause a shut-down problem. (never had much luck in using a DMM to test it though; besides was always inexpensive).
While I can not be sure in your application, in my previous experience with Matsushita's power supplies, TL1431 along with the existing opto-isolator were among the top culprits in shut-down problems when everything else checked out OK.
I might add that electrolytic capacitors in switch mode power supply can also cause problems.

[SOPHM]

Thank you very much vtech for the info...

[SOPHM]

As of now the TV picture only comes on once you turned on and off 2-3 times

[SOPHM]

I replaced IC8002(MCZ3001DB) and found IC6400(MCZ3001DB) to be same chip so I replaced both at once.

Since changed It has been working since then.

[book]

How did you disconnect the 2 red cables/tubes on the D board?

[jts1957]

I'm sure it's described in the literature.

http://elektrotanya.com/?q=showresult&what=KP-46WT520&kategoria=&kat2=all
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