Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then off.

[grimacelord]

Hello this will be my first real post here. I have been reading these forums for awhile, hoping to learn more about component level repair for HDTVs and I have one that I am stumped on.

This is a Sanyo DP32648 32" LED HDTV. The symptoms are no power, no display. The green standby power light will briefly turn on upon pressing the power button, but it will turn off after a few moments.

I am very new to troubleshooting and repairing components on power supplies, so please bear with me here. I have already purchased and replaced the main board, thinking it may have been that based on some research I had done looking into the problem. Having received the main board and installing it, there is no change. Same exact symptoms. This is when I began to troubleshoot further.

I don't know exactly what you guys will need to help troubleshoot this, but having read many threads here, I get a sense of the general questions you guys ask so I have already done what I could or know how to and documented my findings. The multimeter readings were taken with only the main board connected and not the inverter. Here they are:

• All capacitors appear to be in good visible condition (i.e. not bulging, etc.)
  
• The large main capacitor C800 marked 240V/470uF reads at 169DCV while the TV is plugged in and either powered on or off. There is no change.

The pins on the main board connector read as following:

Plugged in and OFF:

PSON: 0.00
5V: 5.04v, no green light on face of TV.
12V: 0.10v
24V: 0.00

Plugged in and ON:

PSON: 5.00v
5V: 5.00v
12: 0.11v
24V: 0.00

I am afraid that this is where my knowledge of what to do next ends. Hopefully you guys can help me. I have a soldering iron and basically all the tools I would need to further troubleshoot this upon your direction. I have attached some pictures below. I hope it's enough, but ask if you need something more specific. Thanks a lot!

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

It may well be the photo but the pins on the transformer look as though they need soldering.

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

It may well be the photo but the pins on the transformer look as though they need soldering.

I suppose it does look like that in the photo. The pins are all soldered well on the underside. Here is a photo for the transformer pins at an angle to show what I mean. Thank you though!

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

What are the IC part number given on top of them for IC601, IC900 & IC 301

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

What are the IC part number given on top of them for IC601, IC900 & IC 301

Here are the part numbers you requested:

IC601:
DLA001D
DEI 912P833

IC900:
2A08417
5541

IC301:
LM258A
88M
AN3E G4

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

In a thread on this forum they replaced a faulty DLA001D with a L6598D so it may be worth checking you have the voltages on that IC.

Can you carefully check what dc voltage there is between pin 10 & pin 12.

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

Have a read through the following thread which may help you.
https://www.badcaps.net/forum/showth...hlight=DP32648

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

In a thread on this forum they replaced a faulty DLA001D with a L6598D so it may be worth checking you have the voltages on that IC.

Can you carefully check what dc voltage there is between pin 10 & pin 12.

Plugging just the power supply in and not connected to any other boards or powered , it reads 0.00v between those pins. It also reads 0.00v when plugged into the main board.

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

You need to apply power which is why I said be careful taking the readings that your probes do not slip.

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

You need to apply power which is why I said be careful taking the readings that your probes do not slip.

I re-tested with power on this time and same reading. 0.00

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

With your meter connected across both legs of C800 what voltage do you have.

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

With your meter connected across both legs of C800 what voltage do you have.

C800 reads 170DVC whether it's plugged in and off or plugged in and on. It makes no difference.

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

What is the part number on Q601 & Q602

[budm]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

Just in case:
Sanyo 1AV4U20C17201 Power Supply Unit (DPS-153AP-1 A)
http://www.shopjimmy.com/sanyo-1av4u...pply-unit.htm#

[budm]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

Fusible resistor R632 (under the heatsink) is OK?
pictures provided by shopjimmy.

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

What is the part number on Q601 & Q602

Q601 & Q602 both: FQP16N25C

Just in case:
Sanyo 1AV4U20C17201 Power Supply Unit (DPS-153AP-1 A)
http://www.shopjimmy.com/sanyo-1av4u...pply-unit.htm#

Thank you, budm. I also had this same part bookmarked in case I had to bite the bullet and just replace the board. That's what I have always done though, replace the entire board. I wanted to try and replace the faulty components and become better at diagnosing/troubleshooting and ultimately fixing what's wrong rather than just swap the whole thing out. I understand that I still might have to though...

Fusible resistor R632 (under the heatsink) is OK?
pictures provided by shopjimmy.

I'm still very new at this sort of thing, so I hope I am doing this right. I set my multimeter to the 200 ohms setting and I removed one leg from the circuit and it reads 14.9 but then declines down to 00.5 where it stays steady. If I am doing something wrong, please let me know.

[budm]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

So you measure the resistance between the two legs of that resistor with one leg of the resistor not connected to the board anymore and it shows 14.9 Ohms and then go down to 0.5 Ohms, right?

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

With the power supply disconnected from the mains can you put your meter in diode check mode and compare the two mosfets.

Black lead on D and red on S, then reverse the leads. Readings.....
Black lead on G and red on S, then reverse the leads Readings.......
Black lead on G and red on D, then reverse. Readings...........

[grimacelord]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

So you measure the resistance between the two legs of that resistor with one leg of the resistor not connected to the board anymore and it shows 14.9 Ohms and then go down to 0.5 Ohms, right?

Correct.

With the power supply disconnected from the mains can you put your meter in diode check mode and compare the two mosfets.

Black lead on D and red on S, then reverse the leads. Readings.....
Black lead on G and red on S, then reverse the leads Readings.......
Black lead on G and red on D, then reverse. Readings...........

I was actually*moving ahead a little bit when you sent me that link earlier from that other thread. I began troubleshooting on these on my own and I have actually removed both Q601 and Q602 from the board entirely because apparently still being in the circuit can give some funny readings. That's what I read anyway. Here is what they read.


Q601:


Black lead on D and red on S, then reverse the leads: 577
Reversed: Meter reads 1, but it always reads 1 when it's not touching anything even.

Black lead on G and red on S, then reverse the leads: 1
Reversed: 1

Black lead on G and red on D, then reverse: 1
Reverse: 1




Q602

Black lead on D and red on S, then reverse the leads: 578
Reversed: Meter reads 1, but it always reads 1 when it's not touching anything even.

Black lead on G and red on S, then reverse the leads: 1
Reversed: 1

Black lead on G and red on D, then reverse: 1
Reverse: 1

I also followed this video on how to test MOSFETS. It essentially involves shorting all 3 pins with the black lead then placing black lead on S red on D, while keeping the black on S, move the red lead to G for a moment and then back to D. This apparently shows how it acts as a capacitor and charges it. One of the MOSFETS will charge up to a point where my multimeter stops reading it, while the other will only charge to 115 and sit there, unmoving. I don't know if this information helps or not.

[dick_barton]

Re: Sanyo DP32648 32" LED HDTV - No power/display, standby PWR light turns on then of

The mosfets appear to be fine given those readings.
A circuit diagram would really come in useful at this point.