Re: Samsung 24" power supply BN44-00195A first stage voltage?
thanks - yeah, I am removing the glue right now. -)
I started with the cap CM808 and now I am in process of removing it from the QB802. My first switcher repair and I am removing glue. Interesting. -)
Actually - could you please say what the difference is between the two chips?
It looks like the sparking is what killed the whole device - and it seems the voltage came from the area of that IC. It had to - since sparking is gone with power disconnected from the 2 MOSFETs driving the final transformer...
andy2
Member
Last Activity: 08-16-2012, 12:18 PM
Joined: 08-12-2012
Location: torrance
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
I'll remove the glue. But right now I am inspecting the QB802. I think it is burned. It should not pass the 16V with the collector of PC801S disconnected.
Right?
This optocoupler has a different part number than the print. Board says PC802S and it is the first one from the edge of the board. I took out the jumper J810, so I expected the M_Vcc to be 0V, but it is going through.
I also see a small chip in the TDA4863G - it looks like that part is gone too.Leave a comment:
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Pictures
All right everyone, thanks for your patience, I uploaded the pictures as required. -)
But I should also admit to making few innocent mistakes. I should have a pole in front of my desk with a road sign saying parts numbers on your board don't match the schematic. -)
Anyway - I was to remove the DB803 right? Well, I did remove a DB803 as it was printed on the board - but guess what? I actually should have removed DB804, because that's how those parts are messed up. -)
The damage is clear - it is that jumper I mentioned - before (immediately...Last edited by andy2; 08-15-2012, 12:18 PM.Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
update:
The 11N60 QP801S mosfet is blown, but that was not a primary problem.
I also saw a burned shunt - it was covered with glue so initially it was hard to see - but now I connected the power with QP801S removed and the DB803 disconnected but everything else in place and I saw a huge spark going over that broken shunt.
The shunt number is J823 and it is not shown in diagram. Only on the board.
It is close to that big cap. Right next to RB801S resistor but it is a separate circuit....Last edited by andy2; 08-14-2012, 11:09 PM.Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
Question:
My plan was indeed to remove the RM801 first and check the 5.2V. But since you mentioned the other parts removal - why do I need to remove RM831 with DB803 removed? I thought removing the DB803 diode cuts off the power M_Vcc so there should be no voltage on pin 15 of the ICM801 and the voltage on enable pin 9 would be low - am I correct?
Also - since the PRC_out shunt RM801 is taken out - then the QM801 and subsequently QM802 would not be powered so the 24V side would not power...Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
thanks guys, you are great, but I am gonna take it slow, because I have to work. I'll not hesitate to ask about specifics later.
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
There was a loud explosion noise from the monitor and it stopped working. -)
The board has 1 fuse blown and I just started on it. No visible damage though.
Thank you for that jpg. It's very very helpful....Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
Thank you guys. I am glad I found this forum. -)Leave a comment:
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Re: Samsung 24" power supply BN44-00195A first stage voltage?
Thanks, indeed after reading the TDA4863G description today the DC voltage I asked about should be in range of input AC times 1.41. It is input dependent. For the US ~120Vx1.41=170DC or so, not more. But I am puzzled by this voltage increase you keep mentioning - why would it increase with load? It shouldn't... Unless the measurement is sensitive to noise. The maximum voltage on that cap shouldn't exceed the mentioned value so with 240V rated AC input it should be maximum 338V DC or so. I think. For a 450V rated...Leave a comment:
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Samsung 24" power supply BN44-00195A first stage voltage?
The power supply is made by Dong Yang - BN44-00195A
It is a standard power board for Samsung 245B 245BW and 2493HM
The diagram is here:
[url]https://cdn.badcaps-static.com/pdfs/37e40dc6e13bb8b5d00b1cf8a620fd8c.pdf[/url]
Question:
What voltage should I expect on the first stage of that switcher - on that big cap in the center of it?
On the diagram it is called PFC_OUT and it is the voltage measured directly on that cap which per diagram is CP803 and should be 150uF and on the board it says CP801S and it is 82uF cap. It is the same...
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