Samsung HPT4254X BN44-00161A P.S.Dead

[Ltank]

Hi the power supply was working then started cycling on/off. The Service Manual proceeddure walked me through a procedure and said the Control Board was bad.
I put a known good one in and set was still dead. Put original in and had same results.
But previously I sprayed Freeze Mist on the two 0723 daughter boards on the P.S. and it worked for a short while. Should have bought the P.S. instead but I blindly followed the service manual suggestion.
On the board is a MC33067P Resonate Controller IC, the back is SMD 3 leg zenner diodes. With codes of ZG, ZH and 18Y. Problem is that the ZG and ZH get looked up and that # is shown as a 2 legged device at both Digikey and Mouser. Any suggestions? I previously had Seen a post on the daughter board but can not find it again. Strange that some fixes are easy and others are another story. Any help is appreciated.

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I saw this video on U-tube but the guy was hard to understand and the volume was low. https://www.youtube.com/watch?v=sBiic_SV9KY
I found a complete repair for the PS at for 75 bucks but i did not need the whole kit. http://www.preher-tech.com/Parts-Kits.html
I know the problem was on the sub board so I got the part numbers and ordered them from Mouser. I hope I selected all the right parts. We shall see!I will keep you posted.

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I finally found a P.S. schematic so I will post it to save you guys any head ache from trying locate one.

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Power supply has good 5vdc standby but relays RL801S and RL802S dont energize to put 120vac to the Bridge Rectifier DB801S that gives power to the rest of the power supply. The relays check good 270 coil resistance and operate when tested on bench P.S. Feels strange to work in the front section of the supply. Almost all my other problems have been on the secondary cold side. I got pretty good on those.I really hate to spend alot of time on it but it bugs me now. And it the principle that I dont want to let it win. Doing industrial electonics for years was swapping boards. The copany did not allow componant level repair. I hope I am on the right track. Any help is appreciated.
Thanks

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I looked at the PS repair kits online and they have caps, mosfets and parts for the Sub 1 and Sub 2 board. I checked caps ESR, changed out the Sub 1 and 2 board IC controller IC, check other caps. No shorted Mosfets or fuses
the relays that supply 110vac to bridge rectifer are not turning on. Evidently
not getting VCC and VCC_S to RS850 and RB854. Any Ideas?

[prism109]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I am trying to troubleshoot my bn44-001661a power supply my VE voltage is reading 15 vdc not the 102 vdc it should any ideas what to check?
Thanks

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hello gents

Could you please tell me what the problem is if I haven't got 5V on stby ? I only have 3,2V or something like that and I don't know why? I have measured everything from that area and they seems to be ok.
Could you please give me some advice for a beginner? I'm not stupid and I've fixed the ex PSU but this one is doing my heading. The PSU came from USA and I'm wondering if its any problem as they are using different voltages?
I'm looking forward to hear from you guys.

Thank you

[budm]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Diagram:
Pictures of your board?

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hello

I have attached 2 pictures. I have replaced the mosfets, smd resistors, diodes, capacitors but still no click. Its something on st by I think but I haven't got too much experience to find the problem. That's why I need your help.

Thanks
Cris

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I spent alot of time on it and finally gave up and bought another. I did not try to repair it any farther. Sorry. I tried rebuilding the two small daughter board but it did not fix it.
I know more about PS now but my problem was that the relays that supply 120vac to the bridge rectifier was not turning on giving voltage to the PS

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Exactly what is the P'S do or not do? Any voltages ?

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hello
I had a PSU which I've managed to fix it but then I've done a short and I burn it and it was dead. Few weeks ago I bought a PSU from UK as was cheap and now I'm trying to fix it.
The voltages I've got just 3.4V at CN807 and nothing else. I've checked the mosfets, bridge rectifiers, caps, controllers etc and still dead. I took the chip ICB802 viper from the old board and I've change it, I changed a new ICP801, I've changed the SUB1 and SUB2 chips, transistors smds. Still no click. Its doing my heading but I'm never give up.

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

The "new" PSU was from USA sorry and I don't know if this is any problem as you are using different voltage.

[flocko]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hi you need 5v standby on the board when you have this then PS-on needs to go low and the relay will click then you need he VS-on to go high that will bring the rest of the board to life, I have found in the past that the main fault with this board will be the lead free solder used and cracking on components you need to have a good look on the back of the board and just reflow were you see any bad joints Flocko

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hi Flocko and thank you for your info. I have resolder entire board and I've changed the fets and the resistors smd and the diodes near the fets so it's still no click.
We are using 230V in the UK and the board was bought from USA and maybe this could be a problem. I have posted the schematic see above. Thanks. Cris

[Cristian80]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Hi

I've changed some resistors smd, I've checked the Viper22A as I have 3 but still 3.2V. Its doing my heading.

[coreyand]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

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?

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.

[Ltank]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

I would check every power mosfet and transistor for open or shorts. Then check the diodes forward and backward resistance with the diode check on meter. may have to lift one leg of componants when checking. Check ESR on electrolytic caps. Tedious I know. Check reistors for discoloration due to heat. Viisually inspection dont always show a reistor that is burnt open. If you find a open reisistor check the mosfet or transistor associated with it. All fuses OK?

[coreyand]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

All fuses okay, when I got the tv the fuse by the caps were blown but replaced it and it has not blown again. Still have not made any progress. I just brought a 52 samsung home with a good screen and possibly just needed to clean the connections on the tcon board. Not even going to bother with now due to the panel being broken from a screw I didnt see laying on my work table. Now I have the power supply from it for parts for this tv. Gonna check all diodes, typically a bad diode would pop the fuse wouldnt it?

[coreyand]

Re: Samsung HPT4254X BN44-00161A P.S.Dead

Alright, I checked all the diodes they all seem to be okay. I seem to have something wrong with QX801, Qx802. Are these IC's? Either way one shows a short on all legs so something is up with that but what are the values supposed to be at for these. This is what is printed on them IC36AS, FQPF, 13N50CF. Also the leg these are connected to is where all the other components are that have been replaced. Any suggestions from here would be helpful. Thanks.

To add, I do get 5v on the standby but anywhere else Ive tested either a low reading compared to what it should be, all the while the clicking goes on in the relay.

Didnt mean ICs, meant mosfets