haier le42b1380 power supply issue

[freakaftr8]

so I picked up this 42 inch Haier led tv with some shorted MOSFETs that power the 12 and 24 volt supplies. Power supply model htx-pi420402a.
shopjimmy has a repair kit for it that supposed to repair every known problem with the power supply which there are three different issues that can happen I had the issue where I had no back lights and no 24 volt or 12 volt to power to the main board and the T CON board.
I replaced known bad components including some LED drivers. I bought the kit and replaced every component and now I have a chirping standby and I found an extra part not included in the kit which is a Schottky barrier diode that shorted and cracked. replaced that all on the secondary side of the power supply I even replaced every component just to be sure.
I had found a few that were iffy but still have absolutely no power on 12 on the 24 volt even though I have standby although it's chirping.
In my knowledge in the past I have come across these power supplies having shorted rectifier diodes I have not found any bad part now but yet I still have no 12 volt dunno 24 volt. Anyone have any experience on this particular power supply?

[ReeceyBurger123]

Re: haier le42b1380 power supply issue

Could you upload clear pictures please of the boards please ?

[freakaftr8]

Re: haier le42b1380 power supply issue

[freakaftr8]

Re: haier le42b1380 power supply issue

it seems I have exhausted every effort to test every component on this board and I'm still not getting 12 volts or 24 volts this is really weird anyone have any ideas?

[selldoor]

Re: haier le42b1380 power supply issue

Pictures are not really clear enough for trouble shooting - shooting them in daylight usually gets better result and they should be posted on the forum using manage attachments. I have added these three so the dont disappear

With just the power supply connected to the mains what voltage do you get on the two BIG caps
Care will be high voltage DC

[budm]

Re: haier le42b1380 power supply issue

Are you getting >360VDC (160~170VDC when TV is plugged in but power switch is not activated) on the the two legs of the main filter 450VDC caps when power switch is activated? Without boosted PFC Voltage, the rest of the switched supply will not work.
Any Voltages on any of the pins of the connector that goes to the man board?

[freakaftr8]

Re: haier le42b1380 power supply issue

YesI'm getting 384v at the filters. Have standby and 5v to mainboard. i press power button I get green LED but the 12 volt and 24 volt just do not come up. I replace various MOSFETs diodes and regulators that come with this kit. and I apologize for the pictures unfortunately using my cell phone sometimes it doesn't seem to post properly.
thanks for fixing the pictures for me if you look in picture 3 you'll see the 12 volt and 24 volt regulated output supply that includes the two MOSFET transistors replaced and the two led controllers

[freakaftr8]

Re: haier le42b1380 power supply issue

Looks like others have this same or similar issues. They use this supply in different branded tvs all the same unit. Seiki, viore, haier. All cheap junk. Panels not even samsung. Some off the wall brand.

www.badcaps.net/forum/showthread.php?p=500264

https://www.badcaps.net/forum/showth...ighlight=Seiki

[johnboy1313]

Re: haier le42b1380 power supply issue

Unfortunately, I have nothing to add here. My thread is linked in the post above. I have the same, no 12V, no 24V, no backlights problem with the same PSU in a Seiki SE421TT. I was just about to pull the trigger on the kit but I don't want to throw away money. I will be watching this closely.

To the original poster. What were the part numbers of the two driver ICs and the two FETs included in the kit? I want to try to source them individually.

[freakaftr8]

Re: haier le42b1380 power supply issue

Hi johnboy I don't have the part numbers with me but none of the actual semi conductors that are replaced on the board are the physical part numbers from the old ones coming off the board there all parts that have been either substituted or the originals are no longer available the new part numbers I will get back to you tonight on as soon as I get home in a few hours. but before I do this there are two barrier diodes that are located on the top of the board near where the LED ouputs are make sure that both of these diodes test good and are not shorted.

[johnboy1313]

Re: haier le42b1380 power supply issue

Do you mean the two in the pic labeled DF1 and DF4? If so, no, they aren't shorted.

[budm]

Re: haier le42b1380 power supply issue

That grey rectangular cap laying on its side next to the two min filter caps, can you read value and verify its capacitance?

[freakaftr8]

Re: haier le42b1380 power supply issue

Ok that cap is a 223j so .022uf. It reads ok.

For johnboy the two mosfets are MDD1901 AK065CGG and the led controller ics are 13408y tl494c

[johnboy1313]

Re: haier le42b1380 power supply issue

Thank you.

[budm]

Re: haier le42b1380 power supply issue

Hmm, I just look in my garage and see that I have this Seiki SE421TT that was dead and did not have time to look t it yet.
I just plug it in and it came on!
I will take it apart next week and take pictures and Voltage reading on the power supply board when I am off work next week.

[freakaftr8]

Re: haier le42b1380 power supply issue

Ok that would be great Bud! Thanks. Also I'm curious to see if the 12 and 24 volt supplies come up if the LED strings are disconnected from the power supply I am possibly in just very slightly think I'm onto something. As in low resistance reading on one of the connectors which would prove what others have said on this forum about shorted LED strip wiring against the grounding frame of the LCD panel

[budm]

Re: haier le42b1380 power supply issue

I hope it uses the same board as yours. I do not know why it is working right now, it is still on.
I will do the details experiment next week with LED string removed to see what condition it will go into.
that is what I heard too that the wire to the string of LED shorted out to the chassis, what you can do is to remove all the LED string connectors an take the reading between the chassis and the pin on the LED wire connector to see if it will show any resistance, it should show open circuit.

[budm]

Re: haier le42b1380 power supply issue

OK, the backlights just went off, it will flashes on for seconds and goes off, so it looks like after warm up it stops working. I have a feeling that it will be LED string problem.
I see that the bottom left section of the screen is dark when it flashes on for seconds, so not all the LEDs are on, I did not see that problem when I first turn it on 1/2 hour ago.
It looks like it has 4 LED strings, the two on the top edge and the one on the bottom right edge are on, but the bottom left edge is not on.

[freakaftr8]

Re: haier le42b1380 power supply issue

Interesting. Yes your set has the same ps.. All my led strings read open .You should remove that connector tthe the strips out on and get an ohms reading. That's one expensive power supply. High in demand.

[freakaftr8]

Re: haier le42b1380 power supply issue

Also probe all 4 voltage output on ps