Sanyo DP42746

[cmj21973]

Someone threw away a perfectly good 42" plasma tv!

Yeah right.


Found this set on the curb waiting for trash pick. No remote or power cord. Looked in trashcan for them, but seen dog pile bag on top and said screw them.

I have a power cord that will work. Can get a remote if you all think its worth saving.

Took back off and plugged it in. No standby light, if it has one.

Voltage reading just plugged in:
Va=70 measures 0
Vsc=-190 measures .21
Vs=203 measures .01
Ve= 84 measures 0
Vset=195 measures 0
Vg measures .12
5Vsb measures 5.19
D3V3 measures 0.01
D12V measures 0.23
D5V measures 0.59

Pressed power. Front red LED on, steady, and screen black. No signal source attached.

Green LED error code, on PSU, flashes 12 times indicating problem with D12V.

Voltage power button pressed:
Va=70 measures 0.06
Vsc=-190 measures 0.19
Vs=203 measures 2
Ve= 84 measures .12
Vset=195 measures 0.05
Vg measures 0.06
5Vsb measures 5.19
D3V3 measures 0.01
D12V measures 0.23
D5V measures 0.5

Disconected the power cable to what I believe is the Y-SUS board. Applied power and pressed power ON button. PSU code error LED stays lit, no flashing.
Reconnect Y-SUS power cable and disconnect ribbon connect it to what I believe is the T-CON board. Applied power and pressed ON button. PSU code error LED stays lit, no flashing.

Voltage reading in this state:
Va=70 measures 69.7
Vsc=-190 measures -189
Vs=203 measures 201
Vset=195 measures 195
Vg measures 15
5Vsb measures 5.2
D3V3 measures 3.4
D12V measures 12
D5V measures 5.2

Questions:
1) It's a 2006 set should I spend money on fixing it or part it out.
2) I'm fairly sure it needs a Y-SUS board and the Upper & Lower Y buffer board, but how do I test if the display panel is bad or good?

Have Owner's manual and Service Manual.
Can't upload them, will PM/Email if needed.

[tom66]

Re: Sanyo DP42746

It's a HDTV so it might be worth fixing.

I would check for shorted diodes on the output side and for a PSON signal.

[PlainBill]

Re: Sanyo DP42746

I wouldn't even bother parting it out, except for the main board. This has the unholy trio of LJ92-01200A Y-sustain and LJ92-01202A and LJ92-01203A buffers. You are correct, you will wind up replacing or repairing at least the Y-sustain and one of the buffers. The upgraded buffer pairs are available on eBay for $150. Repair service on the LJ92-01200A will run $75 with shipping both ways. I'm guessing that a remote will run $30.

PlainBill

[cmj21973]

Re: Sanyo DP42746

Found test for Y-SUS, Upper & Lower Y-Buffer.

http://blog.coppelltvrepair.com/2010...er-boards.html
http://blog.coppelltvrepair.com/2010...according.html

[PlainBill]

Re: Sanyo DP42746

Found test for Y-SUS, Upper & Lower Y-Buffer.

http://blog.coppelltvrepair.com/2010...er-boards.html
http://blog.coppelltvrepair.com/2010...according.html

Based on my experience, there is a problem with this. If you find the upper buffer is not shorted and you replace only the lower buffer and the Y-Sustain there is a very good chance the upper buffer will short when power is applied, taking out the Y-Sustain.

PlainBill

[cmj21973]

Re: Sanyo DP42746

Correct, replacing all three boards is a must.

Well, I'll put set back together and store it until I can afford to buy parts to fix it.

[cmj21973]

Re: Sanyo DP42746

Both Y-buffers tested bad. With the Y-buffers removed still get 12 flash D12v error code, so Y-SUS is bad also.

I'm going to do a little dissecting on the Y-buffers.

If I can't fix and watch it, I'm going to learn from it.

[cmj21973]

Re: Sanyo DP42746

After some more web searching,

I've decided to rebuild the Y-buffers and Y-SUS boards.

Y-SUS board:
1) IPM IC STK795-518 tested ok
2) all fuses are good. (small through-hole fuses and large ceramic)

Web search turned up location of shorted power mosfet(s).
Will pull and check them. I'll replace the shorted ones or all of them.

If this repairs the Y-SUS to working status, I will then tackle rebuilding the upper & lower Y-buffers.

My reasoning:
Buy Y-SUS and Y-buffers(upper&lower)= $200-$300
IF the only thing wrong with Y-SUS is short power mosfet(s)= $4-$28

[PlainBill]

Re: Sanyo DP42746

I suggest you view the following two videos. They are from a professional TV repair shop and a TV with a problem similar to yours.

http://www.youtube.com/watch?v=VyEzo...feature=relmfu
http://www.youtube.com/watch?v=cbEJn...feature=relmfu

PlainBill

[cmj21973]

Re: Sanyo DP42746

Thanks for the vids.

If I can't repair the Y-SUS, I promise it will be my stopping point.

Now it's my understanding that if the upper and lower Y-buffers are removed and that the Y-SUS is good then when the set is powered up, the error LED on the PSU will stay on, no flashing, indicating that the Y-SUS is working correct?


P.S.
Thanks to the above vid links, I found these.
http://www.youtube.com/results?searc...05l105l0.1l1l0

[tom66]

Re: Sanyo DP42746

Thanks for the vids.

If I can't repair the Y-SUS, I promise it will be my stopping point.

Now it's my understanding that if the upper and lower Y-buffers are removed and that the Y-SUS is good then when the set is powered up, the error LED on the PSU will stay on, no flashing, indicating that the Y-SUS is working correct?

If the Vs voltage rises to nominal then it's probably okay.

[cmj21973]

Re: Sanyo DP42746

I suggest you view the following two videos. They are from a professional TV repair shop and a TV with a problem similar to yours.

http://www.youtube.com/watch?v=VyEzo...feature=relmfu
http://www.youtube.com/watch?v=cbEJn...feature=relmfu

PlainBill

If I make it to the point of rebuilding the Y-buffers, I already decided to replace all 12 ICs on the buffers.

[cmj21973]

Re: Sanyo DP42746

Got the heat sinks off of the mosfets on the Y-SUS. The thermal compound , what little there was, done harden like tile grout. The heat sinks on the upper and lower Y-buffers were the same way, no wonder they fail.

[cmj21973]

Re: Sanyo DP42746

I should have ask if these IXTA36n30p (Q5006, Q5005, Q5007, Q5008, Q5009, Q5010, & Q5011) could be tested without desoldering them.

You can test them for continuity without removing them, right?

DMM set to continuity (200 Ohms buzzer), place neg. probe to D(tab) and pos. probe to G and then S. If continuity sounds it's shorted (ie bad).

I had one were source was shorted to drain.

1) Since they are all off the board, will this test find any more bad ones?
http://www.4qdtec.com/mostest.html

2) If not, what kind of test should I run?

3) should I just replace them all?

[PlainBill]

Re: Sanyo DP42746

Typically only one of the set will short. They are mounted in parallel, with (I believe) individual resistors on the gate. Replace the shorted one. No other tests required.

PlainBill

[tom66]

Re: Sanyo DP42746

You can temporarily run it with 6/7 MOSFETs but only do this for a minute at a time. Did that on a Panasonic plasma before replacing the FET entirely as a good way of confirming it was at fault.

[cmj21973]

Re: Sanyo DP42746

Seven IXTE36n30p should arrive in mail, today.

Anything I should test/check before I install them, apply thermal heat sink compound, and resolder all three heat sinks in place?

[cmj21973]

Re: Sanyo DP42746

I replaced all seven IXTA36n30p mosfet, reapplied thermal compound & heat sinks.
Installed Y-SUS and connected power cable and ribbon connector to T-CON. Applied power to the set to put it in standby mode. Didn't press the ON button.

The error code LED, on the PSU, is now lit steady. No flashing error code.
The left LED on the T-CON board is flashing while the right LED is lit, not flashing.

Am I correct that the power issue with the Y-SUS is repaired, and that the flashing left LED on the T-con is due to the Y-buffers not being installed?

The upper Y-buffer has one bad (shorted) IC and the lower Y-buffer tested good.

Should I test the set with just the lower Y-buffer or wait until I rebuild both Y-buffers?

[cmj21973]

Re: Sanyo DP42746

Installed lower Y-buffer and the plasma panel works, atleast the lower half.

Still don't know what the left blinking LED on LJ92-01270 indicates.

Connected tv cable to both digital and analog antenna inputs, nothing. Tried changing channels and volume using the set control board buttons. Pressing the volume and channel buttons caused the set to cycle off and on.

[dcavman]

Re: Sanyo DP42746

just recently got one with the same error code please let me know how it worked out for you