Samsung PN64E533D2F

[krygods]

This TV has no standby light.

I've measured the voltages at connector CN801:

CN801

1 PS_ON - 2.3VDC
2 STBY - 0.53VDC
3 GND
4 +15V - 0VDC
5 GND
6 GND
7 D5.3v - 0VDC
8 D5.3v - 0VDC
9 GND
10 +15v - 0VDC
11 +15v - 0VDC
12 D5.3v - 0VDC

I also tested the same connector with the main board unplugged only change is:

PS_ON - 3.74VDC
STBY - 0.44VDC

I've checked all diodes on the top and bottom of the board and they all test good.

Looks like somebody has changed some of the transistors and one of the ICs on the heat sink.

They did a really poor soldering job so I removed all the components as well as the heat sink cleaned it all up put it all back together still tests the same as above.

This is the first plasma that I've attempted to troubleshoot but 0.5VDC for STBY voltage seems way to low?

Pictures are before the cleanup job. Looks much better now got rid of all that white silicone.

[budm]

Re: Samsung PN64E533D2F

1 PS_ON - 2.3VDC
2 STBY - 0.53VDC

Something does not add up in the reading, if main board only getting 0.53VDC to run the board, then I cannot see how the PS-ON command signal from the main board can be higher than the STANDBY Voltage, it has to be measurement error some where.
What is the board P/N? I need to see the pin names and numbers on the connectors on that power supply board.

[freakaftr8]

Re: Samsung PN64E533D2F

Check fuse F802s. Also the 2 transistors on that bank near F802s. Check middle pin to end pins. Bet the lower one or the upper one is shorted. Also check the other two transistors at the end of the power supply that were replaced. Bad solder connections will automatically short those MOSFETs out. Also if you look underneath the board near the two transistors by the power connector that were replaced there is that IC. That is a regulator IC. That's known to fail as you can tell it looks like its been replaced before.

[krygods]

Re: Samsung PN64E533D2F

Power board P/N BN44-00515A

I'll check all those suggested parts.

Also attached pictures of all connectors on the power board.

[fzabkar]

Re: Samsung PN64E533D2F

Just in case you thought that the white stuff wasn't original:

http://assets.shopjimmy.com/media/ca...00515a-top.jpg

[krygods]

Re: Samsung PN64E533D2F

LoL, yea I knew that stuff was supposed to be there. Whoever tried repairing this board before I got the TV did a crappy job of trying to work around the silicone and heat sink.

[budm]

Re: Samsung PN64E533D2F

OK, you need to check the DCV (between the two legs) on that filter cap I marked.
I also need the P/N of those two devices.
BN44-00515A Pictures provided by SHOPJIMMY.

[krygods]

Re: Samsung PN64E533D2F

Before I saw post #7 I've taken all the transistors from the heat sinks to test for shorts and QS804 P/N 12N50 source and drain are shorted.

[budm]

Re: Samsung PN64E533D2F

QS804 is the the VS SMPS section, it is the lower half of the Half bridge drive for the VS Power transformer. Did it cause the main AC fuse to blow?
Fuse F802S is for the STBY SMPS section. So the STBY power supply should still be working.

[krygods]

Re: Samsung PN64E533D2F

Both fuses test good.

If I put all the transistors back on the board except the one with a short can I perform the testing you specified in post #7?

[krygods]

Re: Samsung PN64E533D2F

QM800 and QM801 P/N D4184

[budm]

Re: Samsung PN64E533D2F

The other MOSFET (TOP drive) should be left out, those two MOSFETs should be replaced at the same time, so I would leave both of them out.
You should be able to power up the power supply board by itself to find out if you do have the DCV between the two legs of the cap that I marked.

[krygods]

Re: Samsung PN64E533D2F

The cap you marked CX858 shows 5.3VDC

[budm]

Re: Samsung PN64E533D2F

The cap you marked CX858 shows 5.3VDC

OK, so we do have DCV feeding the QM800 and QM801 but some how you only have <1Vdc on the STBY pin 2.
Notes; I expect higher than 5.3V due to the Vdrops on the switched devices.

'D4184' I am not sure if the full P/N will be 2SD4184 (NPN) which is not MOSFET.

[krygods]

Re: Samsung PN64E533D2F

P/N is AOD4184 I believe

[budm]

Re: Samsung PN64E533D2F

OK, that makes more sense, it is N-CH MOSFET.
So what DCV do you have against GND on S, D, and G?

[krygods]

Re: Samsung PN64E533D2F

QX800

Gate = 73.6mVDC
Drain = 5.33VDC
Source = 0.45VDC


QX801

Gate = 0VDC
Drain = 5.33VDC
Source = 0VDC

[budm]

Re: Samsung PN64E533D2F

So they are not getting the Gate Voltage to turn them on.
BTW, you mean QM not QX? And the QM800 looks like the print is QM880.
But any how, the Gate of the QM800 (QM880) has the trace going some where which I cannot trace it out.

[krygods]

Re: Samsung PN64E533D2F

Yea it is QM808, I attempted to remove QM808 to get a better look at where the traces go but I've broken off one of the legs so I'll go ahead and order two of those.

I'll get some better pictures in the meantime and also I see that there is a kit available for this PSU from shopjimmy. Should I also order this to have the parts on hand also considering that you said that the bad transistor should be changed in pairs??

Looks like we'll have to work with this board too as I don't see any available other than one that claims to be "NEW" for $250, that seems a bit pricey to me.

[krygods]

Re: Samsung PN64E533D2F

Any suitable substitute for AOD4184 to avoid having to order from China? Seems to be the only supplier I can find for AOD4184.