bn44-00214a no 12 and 24 voltages

[anna1980]

At this moment Im trying to fix this power supply.
Problem is
When I power on the tv the tv the red light appears. It sometimes responses to the remote, sometimes a couple of blinks but thats al

The power supply is a bn44-00213a from which I downloaded the schematics
When searching on this forum I checked a couple of thing.
* I checked all the soldering joints and some of them I touched up a bit
* I did the blowdryer test to check of the capacitors might be the problem. But I didn't expect them to be bad anyways. But that all didnt help
* When not connecting pin 1 and pin 3 of cnm802 a get a steady 5.26v. No more voltages on the rest of the pins. The Bridge rectifier shows 230ac in and 310vdc out. So the main cap.
* when connecting pin 1 and 3 the voltages on the connections jumps from 5.26 up and down from 3 - 3.3 volts. Maincap is still 310 volts

Something I did see was some black (looks like burned) near CX802S, NT811 and CY802S and CY801S.
The thermistor is a 5d-15 with a resistance of about 7 ohms. I think a bit high but it went down a soon a the soldering iron came near it.

Somebody got any hints

[R_J]

Re: bn44-00214a no 12 and 24 voltages

Check the voltage ACROSS CB802, CB806, and CP811, these are in the primary and use hot ground, so it is easier to check the voltage across them.
It could be that these caps are bad causing the vcc voltage to drop when the rest of the power supply tries to start up

[anna1980]

Re: bn44-00214a no 12 and 24 voltages

Hi
Just checked them
not connected pin 1 and pin 3 of cnm802
cb802 -> 10.7
cb806 -> 26.6 v
cp811 - > 0

connected
cb802 > jumping from 12-14
cb806 > jumping form 0.6 to 1
cp811 > not really any voltage

[Unspun01]

Re: bn44-00214a no 12 and 24 voltages

The NTC thermistor 5D-15 is an inrush current limiting NTC. Measuring 7 ohms is not too bad. Nominally, the specs say it is 5 ohms with 15mm diameter. Resistance should drop as the device warms up.

There should not be black marks on adjacent components as seen in your photos. This suggests it may have experienced a surge or something.

When plugged in, what is the voltage you measure across the pins of the large capacitor with the red dot on it?

One thing I would do is gently scrape away that brown/yellow adhesive on the front of the circuit board. That junk is known to become conductive as it ages and cause power board issues. There are several spots in your photo that has it. GET RID OF IT. scrape it with a pick or whatever so that it does not bridge any electrical connections. With that adhesive scraped off, try re-connecting the board and testing again.

[anna1980]

Re: bn44-00214a no 12 and 24 voltages

When plugged in, what is the voltage you measure across the pins of the large capacitor with the red dot on it?

Maincap is 310 volts. I am going to double check it tomorrow
its 310volts in standby AND 310 when pin 1 and 3 on cnm802 are connected

[R_J]

Re: bn44-00214a no 12 and 24 voltages

Hi
Just checked them
not connected pin 1 and pin 3 of cnm802
cb802 -> 10.7
cb806 -> 26.6 v
cp811 - > 0

connected
cb802 > jumping from 12-14
cb806 > jumping form 0.6 to 1
cp811 > not really any voltage

In standby CB806 is about right, but when you turn it on something is killing it, either the CB806 is bad (open) or there is something shorted on the m_vcc line after QB802. Check QB802 emitter to hot ground, there might be a shorted component like icp801s, or ICM801
Try replacing CB806 first.

[anna1980]

Re: bn44-00214a no 12 and 24 voltages

Just to conclude my topic. Thanks to r_J. This weekend I finally got the tv repaired. I changed cb806 but no joy. But I had the ICP801S for just in case. And that was it. It's now up and running.

Thank you all