BN44-00496B A5V only have 2.2V

[jeremykum]

Re: BN44-00496B A5V only have 2.2V

After studying the schematic, I want to share this 2S110

Leg 2 - 1.28v seems normal
Leg 4 - 268v seems undervolt (schema shows 308v)
Leg 8 - 9.8V seems undervolt again as per schema 15v

Negative probe at Main filter cap

[dick_barton]

Re: BN44-00496B A5V only have 2.2V

Have you lifted one end of each of the 4 diodes that rectify the 5V dc feeding the A5 output. I think they are probably the 4 larger diodes alongside each other. One of them may be leaky. Also test the capacitors connected to them on the A5 line.

[jeremykum]

Re: BN44-00496B A5V only have 2.2V

Normally there is one DC supply always available at the output which is the standby supply. This powers the mainboard and when the set is taken out of standby sends a signal to the power supply to switch on all the other DC supplies.

If you disconnect the mainboard from the power supply what dc voltages do you have at the connector of the power supply?

Mainboard cable not connected to powerboard
Only have at CM801:
A5V - 2.2V
Power on/off - 0.729v

[jeremykum]

Re: BN44-00496B A5V only have 2.2V

You need to clean the solder balls from between the legs of the mosfet tidy up the solder joint of diode D9808 close by the mosfet

Schematic attached may be similar to your power supply.

Noted, thanks.

[dick_barton]

Re: BN44-00496B A5V only have 2.2V

Normally there is one DC supply always available at the output which is the standby supply. This powers the mainboard and when the set is taken out of standby sends a signal to the power supply to switch on all the other DC supplies.

If you disconnect the mainboard from the power supply what dc voltages do you have at the connector of the power supply?

[jeremykum]

Re: BN44-00496B A5V only have 2.2V

In the center of the burning up , there is a vertical resistance or maybe an inductor coil , it's not clear . Maybe it has changed of value or open ..

Yes, it's an inductor if you referring to the vertical part. Measure 0.4ohm 0.0uH test frequency 200kHz, so not open. But 0.0uH? Anyway at this writing moment, I just test onboard, didn't remove it. And looking at the circuit, I assume this section is for LED strip power.

Can clarify, the powering sequence of a tv powerboard?
I am not very sure the cold side sequence. Is there a standardized sequence as in laptops?

Sorry for the many questions asked, but trying to grasp the whole idea of a tv powerboard.

[dick_barton]

Re: BN44-00496B A5V only have 2.2V

You need to clean the solder balls from between the legs of the mosfet tidy up the solder joint of diode D9808 close by the mosfet

Schematic attached may be similar to your power supply.

[jeremykum]

Re: BN44-00496B A5V only have 2.2V

What has caused the burning up on the circuit board ?

So far, tested the cap there value sufficient, underneath have a mosfet FDD7N25LZ. I removed and tested not shorted. Here I snap to photo at different angle, the bottom side. The topside burnt is exactly underneath this mosfet.

[jiroy]

Re: BN44-00496B A5V only have 2.2V

In the center of the burning up , there is a vertical resistance or maybe an inductor coil , it's not clear . Maybe it has changed of value or open ..

[dick_barton]

Re: BN44-00496B A5V only have 2.2V

What has caused the burning up on the circuit board ?

[jeremykum]

Hi everyone,

I have this board, the output here only available 2.2V at the A5V circuit. Definitely this things doesn't powers up.

B5V
B13V
measure 0

LED connector at D1/DI+ give me constant 90V

So far, I replace optocoupler as the anode/cathode doesn't give correct reading. Also replace the SSC 2S110 out of trying.

Can anyone give me some suggestion?
Also I need the schematic for this board too.

I am familiar on laptop electronics, but not so much on TV powerboard.