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Old 09-30-2012, 10:20 AM   #1
Mr_K
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Post Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

As said, i have a faulty Samsung PSU (BN44-00427A) PD46B2_BSM

The main fuse was blown. All other fuses are fine. There is a short between + and - of the bridge rectifier (BD8015). I have removed both of the big coils to see if the short is on primary or secondary: Primary short after bridge rectifier is still present. But thereīs also something wrong on the secondary side: e.g. Short over D3601. Itīs not the diode....!

Any advise on this one?

Thank you for ur help!
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Old 09-30-2012, 10:29 AM   #2
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Check the MOSFETs for the PFC stage, one is likely short. Post some pictures and we can highlight the PFC stage.
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Old 09-30-2012, 10:39 AM   #3
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Please check at Jimmys They have a nice one

Edit: D3601 is in the top right corner

Last edited by Mr_K; 09-30-2012 at 10:50 AM..
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Old 09-30-2012, 11:08 AM   #4
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

This is an LED set? More and more of these are failing nowadays...

Check the FETs I've highlighted for shorts; you may have to desolder the PFC ones.

Depending on the topology, the D3601 -could- appear short even if it is OK. If you want, you can remove it from the circuit to test, but for now I'd say focus on the primary short.
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File Type: jpg fets.jpg (696.9 KB, 392 views)
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Old 09-30-2012, 11:09 AM   #5
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

[accidental double post - please ignore]
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Old 09-30-2012, 12:08 PM   #6
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

First of all thank you for your quick support.

One of the "lower" FETs (10NM60N) has a short. The other one is fine. The two other FETs (mdf9n50) have no pass in any direction. This seems a bit strange to me.
And there is still a short at the diode. I made a mistake. Itīs named D9601 not D3901. The one in the top right corner. The diode itself is fine. Even after removing all the FETs.

Last edited by Mr_K; 09-30-2012 at 12:36 PM..
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Old 09-30-2012, 12:35 PM   #7
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Can you highlight the faulty one?

If the diode itself tests fine out of circuit, then that is probably not a problem. The diode might in parallel with a low-ohm resistor, for example.
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Old 09-30-2012, 12:56 PM   #8
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

These two. Propably the red one, but im not 100% sure. I may have mixed them while measuring...
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Last edited by Mr_K; 09-30-2012 at 12:59 PM..
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Old 09-30-2012, 02:35 PM   #9
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

They look like they are paralleled; in which case, I'd say one failed would make the other look failed. If possible, remove them from the circuit and test. You should be able to run the set for a couple of minutes with the bad fet removed, as long as it didn't damage anything else.
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Old 09-30-2012, 02:47 PM   #10
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

I already removed all the 4 FETs with the results posted above. Iīll try to get some replacement parts tomorrow and check the board.
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Old 10-01-2012, 01:47 PM   #11
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Ok, TV is working with the faulty FET removed. I was not able to find a replacement part today, so I have to order them. Itīs 10MN60N May I replace it with a IRFBC40? This one is only capable of 6.2Amps.......
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Old 10-01-2012, 01:59 PM   #12
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

I wouldn't recommend it. Closest I can find:
http://www.digikey.com/product-detai...APBF-ND/812095
(9.2A rating, 0.75 ohm)
But NOT insulated! So you will need an isolating mica pad.

or http://www.digikey.com/product-detai...-E3-ND/2799082
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Old 10-01-2012, 02:06 PM   #13
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

These are not easy to get for me.... Maybe this one?
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Old 10-01-2012, 02:10 PM   #14
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

The current rating is too low and the gate charge isn't specified. You didn't mention your country so I can't make suggestions relevant to you.
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Old 10-01-2012, 02:12 PM   #15
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Please check Reichelt I would like to order from them.....in germany.
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Old 10-01-2012, 03:15 PM   #16
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

Do you not have Farnell or RS in Germany?
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Old 10-01-2012, 03:25 PM   #17
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

We have both of them. But iīd prefer Reichelt (i need to order more parts there) OR RS - not Farnell

Last edited by Mr_K; 10-01-2012 at 03:37 PM..
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Old 10-01-2012, 04:13 PM   #18
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

well, RS stock 'em;
http://uk.rs-online.com/web/p/mosfet...633D424F544826
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Old 10-05-2012, 01:36 PM   #19
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

I recieved my FETs today and another problem shows up. With one FET installed the TV is running fine but as soon as both FETs are installed, the short comes back
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Old 10-05-2012, 01:45 PM   #20
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Default Re: Faulty Samsung PSU (BN44-00427A) PD46B2_BSM

After removing the apparently shorted device does it test shorted out of circuit? Maybe there's a physical short on the circuit board, like a damaged trace or solder bridge.

Last edited by tom66; 10-05-2012 at 02:13 PM..
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