Dead Samsung Plasma PS-42C7HD No Standby

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

ok just tried again i am now getting 112v between the legs of that cap you marked CS814

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

ok just tried again i am now getting 112v between the legs of that cap you marked CS814

That is way too low, your AC is about 230VAC, right? So 112VDC is very low.
Meter set correctly?

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

ok checked
all readings a-b b-c etc are 0
diodes ok
however dont know what/how check NTC

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

yes meter set correct am getting 230V ish back at D that you marked

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

NTC is check with Ohm meter.
We need to get more than 112 VDC on that filter cap for the standby power supply. You did not have the meter set to AC when you checking the dc Voltage on that cap CS814, right?

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

no meter set to DC for check on that cap

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

could the thermister be reducing the volts to the cap

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

NTC resistance has to be very high to cause the Voltage on the cap to be that low. Did you check the resistance of the NTC?
Or the filter cap CS814 has lost its capacitance big time.

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

ok just changed CS814 did not have a new cap but took one off an old board I now have 330V between the legs of the cap,
However still no AC at bridge rectifier and no 5v STBY

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

are we getting there?

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

OK, that is start, so the cap tested bad?
So now we have main DC for running the SMPS IC, now we need to get the spec sheet of the SMPS IC to find out which one is the VCC pin.
Yo may want to try heating the electrolytics caps (there are two of them next to the cap CS814 that you just replace) around the STBY SMP IC with hair dryer to see if it will start running.
I think you should recap the board.

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

'However still no AC at bridge rectifier and no 5v STBY' You are not going to get AC at the bridge until you get the standby Voltage to run the main board first, right now the relays are still not on.

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

heating caps still no start

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

Well, we need the P/N of the SMPS IC to look up the spec sheet, mean while you can try replacing those two caps.
BTW, did you already test the rectifier diode in the secondary side of the STBY power supply to make sure it is OK?

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

SMPS IC is a VIPer 22A
Already replaced the bridge rectifier
Will replace the 2 caps tomorrow getting late now here

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

SMPS IC is a VIPer 22A
Already replaced the bridge rectifier
Will replace the 2 caps tomorrow getting late now here

You mean the main bridge rectifier that you said you are not getting the AC feeding it?
The rectifier I am talking about is on the output side of the STBY power transformer.

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

https://www.badcaps.net/forum/attach...2&d=1450304327
The black diode to the right of the STBY transformer and there are two small electrolytics caps to the right of the diode.
BYW, right now you can run the power supply board by itself because we are working to fix the STBY power supply section first.

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

Viper 22a

[london-freddie]

Re: Dead Samsung Plasma PS-42C7HD No Standby

just changed them 2 caps still no 5v

[budm]

Re: Dead Samsung Plasma PS-42C7HD No Standby

Per IC spec sheet, check the DCV between Source pin and VDD pin of the IC.