Samsung 46" UA46C6900

[Blocky82]

I have a 46" Samsung UA46C6900 that continuously clicks on and off once I try and turn it on.

I've read through https://www.badcaps.net/forum/showthread.php?t=48201 but i'm getting different results. I disconnected the PS pin from the main board end of the 18 pin cable and jumpered SB to PS to force the power on with the main board still connected. The tv turns on and stays on (clicking stops) but the screen just flashes on blue every few seconds and is off the rest of the time.

I've looked over the power board and the caps look OK to me (no obvious bulging), so I was hoping someone could point me in the right direction

[dick_barton]

Re: Samsung 46" UA46C6900

Any photo's of the circuit boards.
Disconnect the power supply from the mainboard. Switch on. Do you have backlights?

[Blocky82]

Re: Samsung 46" UA46C6900

Hey, thanks for the quick reply.
I've just tried again and with the main board completely disconnected I get nothing (as expected), with the main board disconnected and the PS pin on the power board jumpered to SB the TV clicks on but nothing comes on the screen, no backlight.

[Andrew F. Ali]

Re: Samsung 46" UA46C6900

You also have to jump the StdBy5v to the BL-ON pin together with the StdBy5v to the PS-ON pin for the Backlights to work. The main bd. MUST be disconnected from the PSU to do this.

[Blocky82]

Re: Samsung 46" UA46C6900

Added a jumper to BL and same thing happens, tv clicks on but no backlight

[attainteddragon]

Re: Samsung 46" UA46C6900

you shouldn't need to jump this ps. just disconnect the harness that goes to the main.
what voltage do you get on cp802 or cp803?
be careful as this is on the hot side. measure on each leg in dcv.

[Blocky82]

Re: Samsung 46" UA46C6900

OK disconnected the harness and measured the voltage across CP802 and CP803, initially they were going up so I left them to see how high they'd go but after 15 and 30 minutes they'd only reached about 39V and start to drop as soon as i measure them

[attainteddragon]

Re: Samsung 46" UA46C6900

disconnect the backlight harness and check the voltage on those caps again.

[Blocky82]

Re: Samsung 46" UA46C6900

Disconnected it, it's only been on for 10-12 mins but looks like the voltages are the same, about 38V

[attainteddragon]

Re: Samsung 46" UA46C6900

can you check the 2 main fuses for continuity.

we will need pictures of the bottom side of the ps as well.

if you only have 38v dc on the main filter caps, i would assume that you had no stby voltage.

[Andrew F. Ali]

Re: Samsung 46" UA46C6900

Are you sure you are using the correct GND to test this 38Vdc that is on the HOT side of the PSU??

[Blocky82]

Re: Samsung 46" UA46C6900

Yeah my mistake I was measuring the caps wrong. Where is the best GND to use? I can't see an obvious one to use.

When power is on the voltage across each of the fuses is 0 so that should mean they're OK

[attainteddragon]

Re: Samsung 46" UA46C6900

gnd on the hot side is on the negative leg of either of the caps that you need to check the voltage on. so, black to neg, and red to pos.
you can have the backlights hooked up to start with.

[Blocky82]

Re: Samsung 46" UA46C6900

Sorry about the delay, been a busy week.
So i was measuring the caps correctly after all. With power on but no jumpers the voltage is only about 40V across the caps. With SB jumpered to PS and BL i'm getting approx 380V across both caps after 15 mins

[attainteddragon]

Re: Samsung 46" UA46C6900

so it looks like this ps has a pull up resister for the bl/on signal.
if you are getting 380v with jumpers in place, are the backlights working? and do you have all of your other voltages on the main wiring harness, if so, it looks like a main board issue.

[budm]

Re: Samsung 46" UA46C6900

It takes 15 Minutes for the Voltage on the cap to reach 380VDC? That cannot be right.
At this point you must report the Voltage readings on the connector of the power supply that goes to the main board when TV is plugged in and when the power switch is activated.
BTW, I need good clear straight shot pictures of the whole top and bottom side of the power supply board, shopjimmy does not have them for me to look at.