Sun 24.1 LCD / Samsung 244T

[budm]

Re: Sun 24.1 LCD / Samsung 244T

I was not sure which one of the 3 caps is connected to pin2 (not 7 as I said) of the IC. I will look at the board to find the switched transistor that supply the voltage to pin2 next.
Pin 2 is VCC.

[budm]

Re: Sun 24.1 LCD / Samsung 244T

OK, check the ZENER DIODE ZDS806 for short, check the DC voltages on QP803 (it supplies voltage to VCC pin 2 of the 12v/24v SMP IC)

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Bud,

In regard to the 3 pins you had me check. I had VDC at 20 and got

top pin = 0
middle pin = .02
bottom pin= .02

Bear with me as I'm not a techie, but I measured the resistance with my Greenlee DM-20 starting with 200 up to 2000k.

At 200, when I first touched the two I would get a momentary reading of 85 up to 155 then it would drop back to 1 again. Again, I would touch it 3 or 4 times and would get a quick reading and then back to 1 again.

Thanks for taking the time to flag the photo for me. Unfortunately, I washed out of Navy flight school due to a slight red-green color blindness issue so it took me a bit to find the spots, but I did!

[budm]

Re: Sun 24.1 LCD / Samsung 244T

"top pin = 0
middle pin = .02
bottom pin= .02"
Do you have the TV power on with power switch activated? There has to be voltage at the middle pin since the PFC circuits are working.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Bud,

I have the power switched on with the paddle switch next to the cord on the panel, yes. And the power board is not attached to any of the other boards. It's on the work table by itself.

[jetadm123]

Re: Sun 24.1 LCD / Samsung 244T

Are you still seeing 374V across the main cap?

[budm]

Re: Sun 24.1 LCD / Samsung 244T

If it is not attached to the main board, then the PS_ON will not be activating the power supply to power up the PFC and the 12v/24v power supply.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Jet, I'm seeing 168 on main cap.

Bud, you're saying I should have the power board fully hooked up with the other signal and inverter boards? If so, I'll do that. What should I re-check after doing so?

Also, after I hook up all the boards, what about the on/off switch that's attached to the plastic front panel frame. The wire harness is in my post #1, picture 3.

Thanks

[jetadm123]

Re: Sun 24.1 LCD / Samsung 244T

Well, if you're back to 168V at the main cap, then it looks like the PFC section is no longer on. Therefore, it looks like we went full circle and are back to where we started. If all the caps had been replaced, then at least we'd have a good starting point for troubleshooting. At this point, I would consider replacing all the small caps and possibly even the large main cap as some members have reported having problems with it. Budm may have other thoughts as what your next step should be.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

I may have mistakenly made those tests you all suggested on the board without having it connected to everything else. Sorry if I screwed up there.

So, if I'm looking at this correctly there are the 3 we've been testing by the IC and 3 more in front of the large cap, for a total of 7? Anywhere local (Richmond VA) I should be able to find these or should I go online? Bud? Thoughts?

Is Radio Shack a place you all don't think highly of? Here's what I found for the large cap on their site. http://www.radioshack.com/product/in...uctId=12438411

Concern is under their specs. 2000 hours +-12??? NTE brand reputable? 100uf 450v

[budm]

Re: Sun 24.1 LCD / Samsung 244T

Hook everyhing back up, plug it into the outlet, turn it on then check and see if we have our >380vdc on the large cap again.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Bud,

After hooking everything back up I still have 166 on the large cap. I restested the 3 small caps ner the IC and got

CM318-----4.26
CP811------4.82
CM809-----9.9

Also added to previous post.

Thanks

[budm]

Re: Sun 24.1 LCD / Samsung 244T

Well, I do not know what happen, we had the PFC working before, the only circuit that was not working was the 12v/24v which we found that we are not getting the VCC to feed pin 2 of the 12v/24v SMP IC. You will have to trace back to what you have done or changed. Time for new board.

[jetadm123]

Re: Sun 24.1 LCD / Samsung 244T

I'll take one last stab at this. Try changing the startup cap circled in the photo. I believe it to be 10uf 50V. If you can't get this value, then try 22uf or 47uf 50V. As this is for testing purposes, we're not concerned about getting the right type of cap. If you don't have old circuit boards that may have the cap you're looking for, then Radio Shack or Fry's should have it. Hopefully, you have a Radio Shack within driving distance.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Thanks for all your help, guys. I know it must be frustrating dealing with someone not skilled in troubleshooting.

One more question- The wire harness in my photo #1. It goes to the front bezel on/off switches along with a couple of other switches like Left/Right/PIP, etc. When I'm testing this board, is it ok that it is not connected to anything or should I try and remove the skinny circuit panel behind the bezel and plug it in?

Also, how much can I expect to pay for a new panel? Ballpark range.

Thank you again,

David

[budm]

Re: Sun 24.1 LCD / Samsung 244T

If the front panel control panel switch board is not connected, then how did you activate the power so the monitor will turn on to generate the PS_ON? Is it also connected to running PC?

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Ok, news flash. I just shocked myself reaching across the board. When I touch the red probe to the ground lug on the board and the black probe to the top of the wide heat sink at the middle bottom of the board I get a VDC reading of 63v. What's up here?

Bud, I just pulled the skinny circuit board off the front bezel and hooked it up to the wire harness in photo #1. However, when I depress the power button I still don't get any of the LED lighting up to signal status.

[roadstir]

Re: Sun 24.1 LCD / Samsung 244T

Now that front bezel on/off switch is connected, I get

CM813 ---563 meter set to 2000ohm
CM809 ----10.36 meter set to 20k
CP811 ----4.14 meter set to 20k

[retiredcaps]

Re: Sun 24.1 LCD / Samsung 244T

I just shocked myself reaching across the board. When I touch the red probe to the ground lug on the board and the black probe to the top of the wide heat sink at the middle bottom of the board I get a VDC reading of 63v.

The heatsinks are likely live on the hot side. See that big black line outlining the board with the word "hot". Anything you touch inside that area is may/likely to cause serious damage.

[budm]

Re: Sun 24.1 LCD / Samsung 244T

Sorry, Wrong post