Samsung 226BW No Picture

[pedro042]

Hey Guys, I have a Samsung 226BW that has no sign of life except that the power light flashes about once every 5 secs. The monitor doesn't respond to any of the buttons. All the caps on the IP baord have been replaced. The 13.5v output to the logic board is measuring 15.7v. Measuring the testpoint voltages on the logic board I've found the following:
1.8v = 1.8v
3.3v = 3.3v
5v = 0v
14v = 15.7v

There is 5v (5.42v) present on the output of IC702 (DC-DC convertor).
Unfortunately I can't locate a schematic, for the particular board, to be able to find where the 5v goes missing.
I've search the forums and cannot find a solution to this particular issue.

I have the same boards as shown in this message:
https://www.badcaps.net/forum/showpo...5&postcount=10

Thanks,
Dave

[alexanna]

Re: Samsung 226BW No Picture

Do any of the voltages change with the logic board disconected?

[Rtech]

Re: Samsung 226BW No Picture

Flashing Power lamp,indicates a problem in the Inverter circuit,eg shorted transistor etc,particularly as you have changed all the caps.

[pedro042]

Re: Samsung 226BW No Picture

Thanks very much for the quick reply guys.

Do any of the voltages change with the logic board disconected?

No change in voltage when the logic board is disconnected.

Flashing Power lamp,indicates a problem in the Inverter circuit,eg shorted transistor etc,particularly as you have changed all the caps.

I'll give them a look tomorrow. Any ideas what voltages I should be "seeing" on the Schottky Rectifier?

Thanks,
Dave

[alexanna]

Re: Samsung 226BW No Picture

These boards are huge problem for me getting solder to melt enough to remove the capacitors, and getting the new caps soldered back in has also caused me some problems.
Suggest you inspect your soldering very closely, gently rock the caps you have installed and watch for any movement on the solder pads.