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

[grimacelord]

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

I'm heading home for the evening, but I will be back to resume troubleshooting at 8:00AM EST tomorrow morning. If you'd like me to try anything then, please post it and I will check this thread in the morning and do whatever it is that you asked and get back to you. Thanks a bunch for your help!

[dskall]

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

Well there is a repair kit for your power supply that will probably fix the problem. You will have repaired the board without just replacing boards. You can test each component on the board that comes in the kit to find the bad part or parts. A good intermediate step between board level replacement and component level replacement

[grimacelord]

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

Well there is a repair kit for your power supply that will probably fix the problem. You will have repaired the board without just replacing boards. You can test each component on the board that comes in the kit to find the bad part or parts. A good intermediate step between board level replacement and component level replacement

I found that same repair kit and used the replacement parts listed in it as a checklist for me to check on my original board. I have a limited understanding of these things and how to go about testing these components properly, but from what tests I did perform, it seems as though the original components the repair kit would replace seem to be fine? (except for the mosfets) I could be doing something wrong though.

So far, the two mosfets that I removed from the power supply do not behave the same, even though they are both the same type. One behaves differently than the other on the multimeter doing the same steps. This doesn't seem normal to me.

No 12v or 24v on the mainboard connector. Power light comes on only after pressing the power button and it turns off within 3 seconds. I have 3 attempts at this before I must unplug the power supply and then plug it back in, granting me 3 more attempts. Wash. Rinse. Repeat.

Main capacitor reads 170DCV whether plugged in and off or plugged in and on.

dick_barton led me to this thread where another person basically was having the same issues with the same TV. This person replaced the 2 mosfets and it fixed it for him.

I see it's requested that repairs be documented as well as troubleshooting, so this is one I recently repaired without asking questions here:

Note: I added DP26648 to the title because the User's Manual does and leads me to the thought that maybe both sets use the same boards. If this is not the case, sorry to have misdirected any readers.

The trouble manifested as a red LED for about three seconds, then nothing, for three attempts. Then, nothing further until the set was unplugged, at which time I could get three more tries.

Voltage checks showed 5VDC, but no 12VDC or 24VDC at the appropriate connectors (CN902 & CN903). There was 163.5VDC across the main capacitor (C800). With each power on attempt (for three attempts), PSON showed 5.01VDC for about three seconds.

There are two MOSFETs (Q601 & Q602) connected somewhat in parallel with C800. Q601 measured 161.0VDC at the drain, 0.0VDC at the Gate and 10.7VDC at the Source during the three second window. Q602 read 1.2VDC at the Gate, 10.7VDC at the Drain and 0.0VDC at the Source during the three second window. I had trouble measuring the MOSFETs in circuit with the diode setting on my meter, so I removed them for testing. They were both FQP16N25C types, but I got different readings comparing them out of circuit, so I ordered and installed two new ones. BTW, readings of the new ones were different from both of the originals, but, of course, matched each other fairly closely.

With the new ones installed, the set appears to be functioning normally.

I went ahead and purchased the 2 mosfets because of how different they behave on the multimeter compared to one another and because Ed Hall here essentially had the exact same scenario that I do and this was his fix.

Should the mosfets not work, I'll try the repair kit out. I wish I understood more about why those components are necessary to replace and how to identify future components that have failed.

Unless someone else has some other thoughts or suggestions for me to try, I'll update once I receive the new mosfets.

[dskall]

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

I learn a lot from youtube videos once you get past the bulging cap videos. norcal715 has very good videos. As others. Also how to test fets. I'm sure not everyone would agree but the cheap Chinese component testers will test a range of components including esr of caps. I think they do a pretty good job, but most need to be removed from the circuit to test good. Only about $15. Just my 2cents