BN44-00516a

[jeffer76]

I have a BN44-00516a that had a shorted Qs802 and Qs804. Probably because the pins had cold soldered joints. F801s was also open. Ordered repair kit from ShopJimmy. Now I have no standby voltage, but PSon has approx. 4.5 volts. I was reading previous forum posts on similar boards (specifically BN44-00514a). My problem is exactly the same as this thread: https://www.badcaps.net/forum/showth...ht=bn44-00514a
Any help would be greatly appreciated.

[jeffer76]

Re: BN44-00516a

Here are some photos of the power supply board.

[jeffer76]

Re: BN44-00516a

Update: Found UQ802 (picture 4) was defective. This part was a part I replaced as part of the kit that was ordered. Replaced part with the original and 5v standby returned.
Since the original problem was QS802 and QS804, I figured it was worth a shot to reinstall this part.

[jeffer76]

Re: BN44-00516a

I am trying to bench test this board to make sure all the voltages are working before installing it into the tv. I jumpered PsOn to ground resulting in my 15v and 5.3 voltages. I was under the assumption that I should also get the Va voltage, but I am still measuring 0v. Do I have to turn on the VS voltage to get the VA? Does VsOn need a high or low to actviate?

[thoma]

Re: BN44-00516a

http://www.electronica-pt.com/esquem...ng-smps-29728/

http://www.electronica-pt.com/esquem...ng-smps-29727/

http://www.electronica-pt.com/esquem...40d5003-29726/


http://www.kenotrontv.ru/forum/files...7-bn44-00620a/

[flocko]

Re: BN44-00516a

Vs-on should be taken high with a 470-1000 ohm resistor to 5v stby that should bring in the Vs+Va voltages

[jeffer76]

Re: BN44-00516a

Thanks for the help. I used a 680ohm resistor across vs-on and stndby. Worked perfectly.

[pokepoke0610]

Re: BN44-00516a

Jeffer76,

It sounds like I might have a similar problem to you (my original post was "Samsung S64FH Sound but no picture then no power"). I have found that QS802 and QS804 were shorted on my board and I have replaced them (I had bought the BN44-00516A repair kit).

My question is how did you determine that UQ802 was defective? Appreciate any insight you might have.

[dick_barton]

Re: BN44-00516a

What is the component number on UQ802?

[pokepoke0610]

Re: BN44-00516a

It appears to be a MCV14A - an 8-bit microcontroller from Microchip if my search skills are correct.

[dick_barton]

Re: BN44-00516a

Can you post a photo of it. Looks a bit odd to have a uprocessor in the power supply so I believe it's a mistake.

[jeffer76]

Re: BN44-00516a

After installing the kit, my 5 V supply was missing. I believe UQ802 is the controller for that voltage line. Since that wasn't my original problem I just reinstalled the original part

[pokepoke0610]

Re: BN44-00516a

I wouldnt trust me either! Not equipped with everything here so I will have to take a photo tonight.

The part from the repair kit I purchased also shows the same marking

MCV14A
-1/SL

It does seem to have a Microchip logo. You can barely make out the Microchip logo in the 4th photo of the 2nd post by Jeffer76 if you zoom in on the 14-pin SOIC.

[dick_barton]

Re: BN44-00516a

Well I can't argue with you since I really cannot make it out but I am surprised that they have used a microprocessor on the power board. Live and learn.

[pokepoke0610]

Re: BN44-00516a

Oh I get it now - you replaced all components on your board with the shopjimmy repair kit and for some reason the replacement UQ802 was defective.

For your board did you find any other components to be bad? I have been trying to trouble shoot on the board. I would prefer not to have to remove the conformal coating to remove the ICE3BR2565jf offline converter - maybe I am just being lazy but my board re-work skills are marginal at best.

[pokepoke0610]

Re: BN44-00516a

Dick,

I will take a photo and post when I have a chance. It certainly seemed surprising to me although micros are pretty cheap and can be easily used for measuring and sequencing rails.

[dick_barton]

Re: BN44-00516a

Dick,

I will take a photo and post when I have a chance. It certainly seemed surprising to me although micros are pretty cheap and can be easily used for measuring and sequencing rails.

Yes, what you say is true but yet another device proned to failure due to corrupted memory.

[budm]

Re: BN44-00516a

Well I can't argue with you since I really cannot make it out but I am surprised that they have used a microprocessor on the power board. Live and learn.

Samsung has been using it for a while, here is the diagram for BN44-00329B that has MCV14A.

[dick_barton]

Re: BN44-00516a

Thanks Budm. I'm reasonably familiar with Microchips products. As I said earlier just another item proned to failure. Thanks once again for the information.

[budm]

Re: BN44-00516a

I do not know why they have to make it so complicated.