Samsung PS-42D4S plasma. Has sound, no picture. Please help!

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Do you have a hair drier you can use it to help diagnose the issue ? ?

Hair dryer? Never heard of such apparatus ;-) Just kidding. I have a hair dryer and I also have a reflow station. What part exactly do you want me to heat? ...and what do you think we're going to accomplish?

Thanks,

S

[ReeceyBurger123]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Ok heat the centre of the Psu where the transformers are. They polly cap (little rectangles) I think are near them any how heat the Psu and see if Vs come up. Sorry for the light handed replies as well in college and have to type fast haha.

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Do you have a hair drier you can use it to help diagnose the issue ? ?

Who's this for a question?

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Who was asked this question?

[ReeceyBurger123]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

I asked it to Sc to help toruble shoot.

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Yes measure. Because there can be 290-300V and not 390-400V.

I did some measurements. I measured DC voltage directly on main rectifiers (BD1 & BD3 - two D15XB60 connected in parallel) and I also measured DC voltage on large filter caps (C5 & C6 330uF/450V connected in parallel). Positive sides of C5 & C6 are also connected directly to B+_PFC. See picture.

Readings when TV is ON (TV is 220/240V model):

Rectifiers: 215VDC
Large filter caps (B+_PFC): 320VDC

Any ideas? Is it too low?? Is that causing my problem - no Vs? What could be the reason?

One strange thing is - I get those voltage readings even if TV is in standby (relay is OFF), but it may be because filter caps are charged and I didn't wait enough for them to discharge...

Thanks,

S

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

IC1 13 pin (vcc) Voltag = ?

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

(B+_PFC): 320VDC It is low voltage. When TV is turned on = 400V

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

IC1 13 pin (vcc) Voltag = ?

I measured IC1 pin 13 (VCC) to pin 10 (GND_H). I see GND_H is not same as RTN (chassis ground) so I suppose all measurements on primary side of PSU must be measured relative to GND_H.

IC1 pin 13 voltage = 17.5V

See pic.


Thanks,

S

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Yes, all measurements on primary side of PSU must be measured relative to GND_H.
Voltage is normal.

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Check IC1 ML4824 (12 pin) output signal.
VCC_S_R
Q3 - Q4
D9, D10
IC1 ML4824

IC1 ML4824 (6 pin) Vdc PC1S (TLP421) IC5(KA431)
IC1 ML4824 (5 pin) VS_ON - PC10S - Q21

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

ml4824 datasheet

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Check IC1 ML4824 (12 pin) output signal.
VCC_S_R
Q3 - Q4
D9, D10
IC1 ML4824

IC1 ML4824 (6 pin) Vdc PC1S (TLP421) IC5(KA431)
IC1 ML4824 (5 pin) VS_ON - PC10S - Q21

Well, let's do it step by step.

First I'll check voltages on IC1 pins 12, 6 and 5. Right?

What do you want me to do with all other mentioned components related to IC1? (VCC_S_R, Q3, Q4, D9, D10, PC1S, IC5, PC10S, Q21) and signals VCC_S_R and VS_ON?

Btw, looks we are getting somewhere step by step, right? What is your primary suspect currently?

Thanks,

S

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Check IC1 ML4824 (12 pin) output signal.
VCC_S_R
Q3 - Q4
D9, D10
IC1 ML4824

IC1 ML4824 (6 pin) Vdc PC1S (TLP421) IC5(KA431)
IC1 ML4824 (5 pin) VS_ON - PC10S - Q21

Here are measurements (when tv is ON):

IC1 pin 12 = floating around 0.3V
IC1 pin 6 = 1.17V
IC1 pin 5 = 0.6V

All measured relative to GND_H.

Thanks!

S

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

And when tv is OFF.
IC1 pin 13 =? V
IC1 pin 12 =? V
IC1 pin 6 = ? V
IC1 pin 5 = ? V

[scokljat]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

And when tv is OFF.
IC1 pin 13 =? V
IC1 pin 12 =? V
IC1 pin 6 = ? V
IC1 pin 5 = ? V

When TV is in Stand-by mode:

IC1 pin 13 = 0.5V
IC1 pin 12 = 0.08V
IC1 pin 6 = 0.016V
IC1 pin 5 = 0V

Thanks!

S

[ReeceyBurger123]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

https://m.youtube.com/watch?v=yE5CrBlsS48

[ReeceyBurger123]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

There is the link watch the video different model yes however Psu is the same and similar issue. I dont think that the Ml4824 chips are at fault to be dead honest.

[ReeceyBurger123]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

The parts that were hanging off the Psu Pcb are the polly caps try heating where they are if not try replacing them they can cause aload of issues.

[Maklaud]

Re: Samsung PS-42D4S plasma. Has sound, no picture. Please help!

Scokljat, when TV is ON. VS =?