Sharp LC-42SB48UT-a no standby voltage

[AcGeorgiegirl]

Re: Sharp LC-42SB48UT-a no standby voltage

OK, so it cannot even maintain the regulated 5V output.
I would try replacing C969 in the primary side and the 4 cap in the cold side by the connector that goes to the main board.

I tested the ic...gave results above...replacing C969 resulted in no change. I'll go ahead with replacing the caps you suggest. Should I also use your earlier suggestion of replacing the IC, now that I know the cap it's connected with is ok, or first replace the 4 caps you've mentioned above?

[AcGeorgiegirl]

Re: Sharp LC-42SB48UT-a no standby voltage

Well, I've just read where I should ground to the filter cap's neg leg when I test the IC...and I did get a little bit different results(the 1st time I used the chassis to ground)....
The 4th pin: .04
All others: -.02 or -.03

[jts1957]

Re: Sharp LC-42SB48UT-a no standby voltage

Set uses BOTH Cold (metal chassis, tuner cover, etc.) AND Hot grounds (Pin #4 of the bridge rectifier or negative terminal of main filter cap, for example).

[AcGeorgiegirl]

Re: Sharp LC-42SB48UT-a no standby voltage

Set uses BOTH Cold (metal chassis, tuner cover, etc.) AND Hot grounds (Pin #4 of the bridge rectifier or negative terminal of main filter cap, for example).

I realize that, thanks. I was wondering if I should have used a "hot" ground with the IC testing.

[jts1957]

Re: Sharp LC-42SB48UT-a no standby voltage

Yes

[AcGeorgiegirl]

Re: Sharp LC-42SB48UT-a no standby voltage

Well, I've replaced all the caps on the cold side, next to the connector(goes to main), and still no change in standby from 4.04v. That's a total of 5 caps, including the one suggested earlier(c969). The only component someone mentioned, I think is the TNY277 IC. I've been trying to find out if a similar IC, from a Samsung tv, I have on a spare powersupply is compatible, and thought I'd ask you guys. It's labeled: A6159 SK603 693C. It is the same size and same pin configuration.

[jts1957]

Re: Sharp LC-42SB48UT-a no standby voltage

No.

[Iepreferred]

Re: Sharp LC-42SB48UT-a no standby voltage

I have same model tv doing the same thing with 4v standby did you ever get it fixed?

[radan]

Re: Sharp LC-42SB48UT-a no standby voltage

ha a set like this with no stb voltage after changing tny277 voltage read 4v without main board connected .after connecting mainboard all voltages read correct and woked perfect

[TWB_Cool]

Re: Sharp LC-42SB48UT-a no standby voltage

Wait i have 4v standby, what should i do?

[jts1957]

Re: Sharp LC-42SB48UT-a no standby voltage

Continue troubleshooting.
Service Lit. links earlier in this thread.