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I have a Sanyo DP55360 55" that has the following symptoms.

Resolved Question:

I have a Sanyo DP55360 55" that has the following symptoms.

Power on - Green light for a couple seconds then powers off (no backlight, display or audio)

It will do this 3 times then will not power up until power cord removed for approximately 30 seconds. It will then allow power up with fault as above.

With back removed, only indication on power up is a blue flashing light (LED ?) on the board mounted top center.

Any ideas ??

Rob
Submitted: 2 years ago.
Category: TV
Expert:  Michelle-Mod replied 2 years ago.

Hi, I’m a moderator for this topic and I wonder whether you’re still waiting for an answer. If you are, please let me know and I will do my best to find an Expert to assist you right away. If not, feel free to let me know and I will cancel this question for you. Thank you!

Customer: replied 2 years ago.

Hi,

 

I haven't received any responses at this time. Any assistance would be appreciated.

 

Rob

Customer: replied 2 years ago.
Relist: Other.
No answer received
Expert:  Michelle-Mod replied 2 years ago.

Sometimes, finding the right Expert can take a little longer than expected and we thank you greatly for your understanding. We’ll be in touch again shortly

Expert:  TV Tech1 replied 2 years ago.

Hmm, got a Voltmeter?

 

If so, then you can see if the power supply is supplying power to the inverter board which lights up the lamps...if your TV's backlights aren't lighting up at all, then I'd see if the backlight inverter is getting power, and if the Power On command line is going active or not.

 

Here is a picture of your Inverter -- Take your black probe, connect it to GND, and measure Vin2 for 12/18/24 Volts.

Check ON/OFF...it should be either 0 or 5 Volts. That turns on the inverter like a light switch.

 

graphic

 

Tell us if you do get a constant voltage on the Vin, and whether you see the On/Off test voltage goes Hi and Low or not.

 

Of course it will all shut off when the Green light stops.....

 

 

Customer: replied 2 years ago.
Relist: I still need help.
Expert:  TV Tech1 replied 2 years ago.

Welcome back, did you run that test that I showed you?

 

 

Customer: replied 2 years ago.

I apologize, I somehow either missed your original response, or didn't get notified.

 

Vin2 - 24.63V

On/Off - Starts at .012V and only jumps to .2V at highest before shut down.

 

Rob

Expert:  TV Tech1 replied 2 years ago.

On/Off-- when it jumps, do you see the backlight lamps light up? There usually are slots on the back of the panel that you can see light come from. If there are none, then try to check the front of the panel, it's best to check it in a dim/dark room to verify.

 

IF they do not light up at all, we should disconnect the plug, put our voltage probe on the pin for the On/Off and see if it goes high/low or stays low.

 

Right now, it looks like the On/off line isn't turning on the backlight.

 

 

Customer: replied 2 years ago.

No backlight response at all.

 

Voltage on cable for On/Off with it unplugged is consistent with earlier readings. It appears to take a slight jump to approximately .1V just as system shuts down.

 

Meter is fairly quick (Fluke 12) however it isn't a recording meter so the .1v is approximate.

Customer: replied 2 years ago.

No backlight response at all.

 

Voltage on cable for On/Off with it unplugged is consistent with earlier readings. It appears to take a slight jump to approximately .1V just as system shuts down.

 

Meter is fairly quick (Fluke 12) however it isn't a recording meter so the .1v is approximate.

 

I was incorrect on the meter. It is a memory type. Max voltage at the On/Off is .380V

Expert:  TV Tech1 replied 2 years ago.

Ok, it looks like the main board isn't firing the inverters up at all. The plug that you were testing. It comes from the power supply board doesn't it. So it could be the main board or the power supply board dropping the Power on command. I know the main board doesn't mark the Pow_On line....Follow the cable back to the board it connects to. Look around the plug. On the board Sanyo usually marks the Pon or it may be labled as INV on (inverter on)

 

We need to determine if the Main board or the Power board is killing the power on line to the inverter.

 

We got our work cut out for us.

 

Right about now, I could use a picture of your entire chassis, a closer picture of your power board and one on your main board.

 

Let me see if I have an example of the reference or legends printed on some of the boards. Nope, the Sanyo markings are too basic to see an On/off line marked on them.

 

Ok, so this is what we'll have to do. Process of elimination.

 

The main board has one cable that connects to the power supply board. It's going to have the 5 volt standby, and a 12 Volt line or a 9 volt, or it may be 15. We will be looking for a 3.3 Volt or 5 Volt line that goes High and Low when the power button is pushed. You will find the line on a 10 wire cable connected between the Main board with all the input jacks, and the power supply board. You can eliminate any lines that provide the standby 5, the 9/12/15 lines, and of course the ground lines too. Anything else is CONTROL lines turning on the power supply/inverter or feeding back any inverter OK line. Look for one that fires up 3 times

 

Right now, I suspect the power supply board more than the Main board, simply because the power supply is more notorious for failures, but I like to check it as much as possible.

 

 

Customer: replied 2 years ago.

Power SupplyChassisgraphicMain BoardgraphicgraphicOK, where to start ??

 

The plug I was testing is actually a split harness with most of the wires going to the PS board and the rest going to the Main Board. The connection I was testing actually goes back to the Main Board as part of a 3 wire harness. Verified I was testing correct input by checking continuity from On/Off test pad to pin on plug.

 

I am including pictures of:

 

Full Chassis

PS Board

Main Board

Close up of markings on PS board for cable going to Main Board

 

Hopefully pics come through OK, 1st timer attaching here.

 

 

 

Expert:  TV Tech1 replied 2 years ago.

A picture is worth a thousand words.....

 

 

graphic

 

This job would be soooo easy if every manufacturer would simply use pictures in their schematics.

 

 

Take a look at the barcode on your main board --

 

graphic

 

TV Tech1, Technician
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Experience: 30 Years experience. Authorized Warranty servicer.
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