BN44-00522A service manual

[lospiratos]

Can somebody please help me to find the service manual for a Samsung BN44-00522A power supply? It's from a Samsung UE40ES7000 TV.
Was able to find BN44-00522B, but not BN44-00522A. Unfortunately they are different.

Symptoms are that the relay switches every few seconds. Also with the backlight disconnected. No voltages are coming up, except the 5V standby.

With the main board disconnected the backlight should work, but it doesn't. Checked with a scope, but no voltage is being applied so it's certainly not caused by the backlight.

Currently I suspect ICM801, but would like to have a circuit first.

[William1967]

Re: BN44-00522A service manual

Not available it seems, you can try to find the datasheet for ICM801 and go from there.

[dick_barton]

Re: BN44-00522A service manual

There looks like a small 20mm ceramic fuse alongside the 68uF, 450V caps. Is that OK?
Some photo's of your board top and bottom may help.

[lospiratos]

Re: BN44-00522A service manual

Both fuses on the board are OK. Will post some photos later.
Can the service manual be requested somewhere? Will Samsung support help with this?

[R_J]

Re: BN44-00522A service manual

Check the value of RM807, if it is open, icm801 is bad. You can also check icm801's internal mosfet between pins 1(D) & 2(S)

[R_J]

Re: BN44-00522A service manual

If you disconnect the main board from the power supply, check if you get B5V and B13V, the backlight may not come on with this power supply unless you supply 5v to the BLU_ON/OFF pin

[lospiratos]

Re: BN44-00522A service manual

I only measure 5V standby voltage, the other voltages are not present.
I think icm801 is ok. At least no shortages on the internal MOSFETs. All fuses are also still ok. Also the capacitors around that IC are fine.
Something I noticed is that there is no voltage present on the VCC pin of that icm801, which is probably not normal. For that reason it doesn't start to oscillate. The high DC voltage is present.

[lospiratos]

Re: BN44-00522A service manual

I think I've found the problem. Transformer TS801 seems to be broken. Does somebody know where I can get a new one?

[R_J]

Re: BN44-00522A service manual

I think I've found the problem. Transformer TS801 seems to be broken. Does somebody know where I can get a new one?

What do you mean "Broken"? that is the standby transformer and it is working. Do you have voltage across CS805? and CS802? QS801 should be the vcc regulator/switch. It will have a zener and a regular diode on it's base to hot ground, and the transistor (and vcc) is controlled by one of the optos

[lospiratos]

Re: BN44-00522A service manual

The 5V output part of it is indeed working. But there are also other secondary windings that generate the voltage for the MOSFET drivers and that part is not working anymore. The windings measure in megaohms range. Some windings even seem interrupted. No short on the rest of the circuit, so not sure what happened. I think it will be safer to replace the board.

[R_J]

Re: BN44-00522A service manual

Yes there are two other windings besides the main secondary, One is vcc for the ic itself the other is for vcc for the rest of the primary ic's . It is rare for the transformer winding to go open, check where the wire comes out of the transformer and is attached to the transformer leg, sometimes the can break there.

Primary
Pin 1= Gnd
Pin 2= Vcc
Pin 3= FB
Pin 4= Drain
Pin 5 =VS
Secondary
6&7 connected together
8&9 connected together