Sharp lc-c32d42u no standby

[crosstalk]

Hi. I have no standby on this power supply in a sharp lc-32d42u. I found D7907 (1N5383B) shorted, so I replaced that and IC7905 (TNY268PN). I have 160vdc on the drain pin of the IC, 0vdc on the source, and 2.2vdc on the EN pin of the IC. I thought maybe the first replacement IC was a bad part, but trying a second one didn't help--still 0v on the 5vdc standby output.

What else should I be checking?

[dick_barton]

Re: Sharp lc-c32d42u no standby

More details in the following thread

https://www.badcaps.net/forum/showth...ight=lc-32d42u

[crosstalk]

Re: Sharp lc-c32d42u no standby

Thanks. I saw that thread too. I checked D7908 and the other diodes near the photocouplers and they were ok. There could be other problems in that area--I'm not too sure how the photocoupler setup on the secondary side is supposed to work to feedback to the smps IC.

[dick_barton]

Re: Sharp lc-c32d42u no standby

So D7908 & D7907 both checked out OK.
What dc voltage do you have between pins 1 & 3

With the power to the set off what is the resistance of TNY268 between pins 5 and pin 8?

[crosstalk]

Re: Sharp lc-c32d42u no standby

Yes those diodes checked out ok. I have 3.53vdc between pins 1 and 3 and 4.24kohms between 5 and 8.

[dick_barton]

Re: Sharp lc-c32d42u no standby

There is a repair kit
http://www.ebay.co.uk/itm/SHARP-Powe...-/141906829894

[crosstalk]

Re: Sharp lc-c32d42u no standby

Thanks for your help. I got it working. Looked more carefully and found R7902D open. Replaced that and 5v standby is back and the tv is working.