Author Topic: I have a powersupply board for TV -> PD46B2-BDY  (Read 170 times)

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Offline Tony.TTopic starter

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I have a powersupply board for TV -> PD46B2-BDY
« on: January 26, 2024, 08:23:53 pm »
I have the board PD46B2-BDY

But internet sais that it is the same as Samsung bn44-00427B ??

I cant agree but it is very similar.

The Schematic seems to be somehow correct but not the labels...But anyway
https://pdfcoffee.com/samsung-bn44-00427b-schematic-pdf-free.html


The problem is that OVP on the led driver side seems to kick in all the time. FLAG on pin 14 on slc4011m  (dont have datasheet on it but found pinout) is high and also ovp1 and ovp2 is high. And then the relay shuts down.

Connected 12V....5V directly to the transistors named 12V....5V.  And i third powersupply to 85V. (normally 85V)

When i turn on 5V...12V the relay clicks.  Instead of having 85V produced by the board a use third powerspupply on the 85V rail and start to increase the voltage. As soon i reach 53V the relay clicks and should cut down the switching by shutting og the mains.  But as i use external powersupply i can still maintain 53V.  The SLC4011M starts to switch as it gets 12V on VCC but now something strange happens.  After the diode that is after the coil it gets 380V.  Boost converter i know.  But this seems WAY to much.  That is why OVP kicks in.   i have tried to unsolder the mosfets that SLC4011 is switching on by one (green track) and ALL 4 coils ...after their diode gives 380V.  When there is no mosfet, i can see switching frequency on the gates (using oscilloscope). But when they are connected i get nothing???  As soon i lower the voltage to 49 V....the relay activates again and no switching is made....no 12V at input on SLC4011M.

PSon is NOT activated 5V during the test.

I have a spareboard that i can put power on and it is stable.  No clicking at all.  But this board as soon i just turn it on...it turns on...then off. On again...and continues like this. Restarting all the time.

Any ideas what king of problem it can be?  if i unsolder the 85V bridge to the coil...the board does not restart. Some kind of problem it is on the leddriver part....  No shortage that i could see.  Used thermal camera and nothing gets warm at all.

The spareboard that i have...stays 85V after the diode that is after the coil even at standby. But this board boost it to 380V even if PS on is low. and no rebooting. But this board seems to start to switch even with PSon low.... and to 380V and as i said...OVP kicks in.

Any ideas?
 


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