42" Samsung HP-T4254 Clicking and more Clicking

[XtraTN]

I've been working on this set for a while. I got it with symptoms of once I plug it into the outlet it starts clicking and that's it.

Opened it up and looks like the previous owner bought the repair kit for this set but from the soldering it was pretty sloppy. So I checked, tested, and resoldered every single component that was replaced.

MOSFET Transistors 4 QX801, 802 & QS801, 802
SMD resistors 12 RS862, 863, 867, 868, 879, 878,
RX802, 803, 804, 805, 832, 833
Diodes 4 DS801, 802, DX803, 804
Fuse 1 F803

I found that QX801, QS801, and QS802 were still bad. So I replaced them. 2 "FQA13N50CF" and "FQPF9N50C"

Plugged everything in and still getting nothing but clicks.... Removed the PSU and checked the MOSFETs just in case and they are still good...
Removed the Ysus, and it still clicks, then with the Xsus, but still clicks... So is it still a power supply issue? I just hate plasmas so much... =(

[capkid]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

You just haven't worked on enough plasmas . The suspect state of the TV because of a sloppy repair attempt can make it a little challenging. Have you checked the caps with an ESR meter?

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Yep, seems two caps were also replaced, Radial Capacitors CX813, 814. Checked those also and they were good.

[capkid]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

I know that Tom has mentioned in the past that these Samsungs sometimes have issues with cold solder joints: https://www.badcaps.net/forum/showth...light=hp-t4254

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Checked for cold solder joints but don't see any. I reflowed any that seem dried though.

I've been looking at other peoples threads for this power supply and it seems that some of my resistors may be in the wrong place. Does anybody have the correct values for these resistors?

SMD resistors RS862, 863, 867, 868, 879, 878,
RX802, 803, 804, 805, 832, 833

[capkid]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Checked for cold solder joints but don't see any. I reflowed any that seem dried though.

I've been looking at other peoples threads for this power supply and it seems that some of my resistors may be in the wrong place. Does anybody have the correct values for these resistors?

SMD resistors RS862, 863, 867, 868, 879, 878,
RX802, 803, 804, 805, 832, 833

I just fixed an HP-T4234 about 4 months ago. I believe the repair kit is the same for the HP-T4254:

RS862: 20 ohm
RS863: 10K ohm
RS867: 20 ohm
RS868: 10K ohm
RS879: 20 ohm
RS878: 20 ohm

RX802: 20 ohm
RX803: 20 ohm
RX804: 10K ohm
RX805: 10K ohm
RX832: 20 ohm
RX833: 20 ohm

Yep, it looks like at least RS863 and RX833 are incorrect on your board.

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Perfect thanks! I was right some of the resistors are in the wrong places, I'll rearrange them and see what happens. I always hate how they block out the labels to the repair kit in the photos =/.

[tom66]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

I'll just leave this here.
https://www.youtube.com/watch?v=za3EixgxBkk

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Whoo I got it, It working now =D. Seems the resistors were in the wrong order, 20 ohms where 10k ohm was suppose to be. I would guess since the resistors were in the wrong place it didn't provide the correct voltage to drive the FETS correct?

[tom66]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

It could have caused any number of possible issues!

[capkid]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Nice. That was pretty easy.

[WALTO TDI]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

I wish my problems were solved so easily!! Well done

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

The tricky part were the MOSFETS. They were NOT shorted that's for sure but I was getting weird readings:

pins 1-2: infinite ("1") in both directions <--(is this an open circuit?)
pins 2-3: 0.536 ohms and infinite in other direction
pins 1-3: infinite ("1") in both directions

but I used my DCA55 semiconductor meter and it told that it was faulty.

[tom66]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Did you use the DCA55 in circuit? Or did you remove them for testing?

[XtraTN]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

It was removed and then I tested it with my DCA55.

The DCA55 would just cycle in the "analyzing phase" and that was it. However I measured the other "FQPF9N50C" and it was able to take the reading just fine stating it was an N-Channel MOSFET.

[Bip38635]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

Thanks for the info. Loose joints on power board.

[Emerica]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

I made similar repair to a sammy found at the garbage.
It would not turn on , only clitck.
Found blown up reg/fets mentioned above inside. Totally blown apart.
Did the suggested repair from preher-tv and above.

Tv would now turn on but after ~5-10mins , it started clicking on and off by itself.

I tried to get the 1000 and 470 caps, to replace them all, but shop only had the 1000's on hand, I replaced all of them and tried again, it's been working for a few days now without turning off.
None of the caps replaced looked bad to the eye. If you haven't, replace all the caps.

[coreyand]

Re: 42" Samsung HP-T4254 Clicking and more Clicking

I have the same board with the the HPT4254X set. Ive got a problem with constant clicking and the set never fires up. Upon inspection this board was previously repaired. I dont know if the parts are correct from the information I have gathered here, The supposed replaced components which are questionable are shown in the pictures I have attached.

Does anybody know the correct reading I should be getting from these? Should they be taken out of the circuit when testing the readings? I did see the reply from capkid with the readout but reading are way different and they are some different ones than he listed so I was looking for some verification.

This is what I am getting with my meter

RX832: 9.95K
RX803: 9.94K
DX804: 9.94K
RX805: 9.94K
RX804: 10.3
RX802: 10.0
RX833: 9.9
DX803: 10.0

Im not sure what kind of reading I should be getting from the IC36AS that are on the heatsink. It looks like there was previous damage here that has been repaired from the old ICs but I cant be for certain if its these ICs that caused the soot left on the heatsink. I removed one and looked it over and didnt see any visual damage, but I could be wrong. When plugged in it just does the repetitive clicking, I do get 5v on my standby though but nothing else.