Samsung PS-42V4S 42" Plasma TV

[Mad Professor]

C13 has been replaced with a new electrolytic capacitor. and still acting the same.


Here are the results from more testing as requested.


I have also attached the SMPS schematic in pdf format, please see below.

Thanks again.

[Armadillo]

Hi;

Firstly Diode Check D801 and D19. Are they OK?

If Yes;

Turn On the TV and measure the voltage at cathode of D801 with respect to Pin 10 of IC1 [gnd].
Is the voltage > 3.5v?

If yes;

Then measure the voltage at the cathode of D19 with respect to Pin 10 of IC1 [gnd].
Is the voltage > 3.5v?

If yes;


Then measure VC_S_F with respect to Pin 10 [gnd] of IC1  [see attached]
Is voltage > 15 V?

If Yes;

Turn Off TV

Set meter to Diode mode, Check PC1S, measure across Pin 4 and Pin 3 for shorts.
Is the measurement OK?

Double confirm C13 that the newly installed Cap is OK, measure ESR, confirm +ve lead is to Pin 5 of IC1.

If YES, then you will have to replace IC1. $1.30 from China. We went through a lot of troublesome steps to confirm this.

Please post results.

 

Edit:

If No VC_S_F;

Measure the voltages shown in attached and post results.

[Mad Professor]

Hi;

Firstly Diode Check D801 and D19. Are they OK?

If Yes; Tested ok

Turn On the TV and measure the voltage at cathode of D801 with respect to Pin 10 of IC1 [gnd].
Is the voltage > 3.5v?

If yes; 16.83v

Then measure the voltage at the cathode of D19 with respect to Pin 10 of IC1 [gnd].
Is the voltage > 3.5v?

If yes; 19.56v

Then measure VC_S_F with respect to Pin 10 [gnd] of IC1  [see attached]
Is voltage > 15 V?

If Yes; 18.01v

Turn Off TV

Set meter to Diode mode, Check PC1S, measure across Pin 4 and Pin 3 for shorts.
Is the measurement OK? Seems ok

Double confirm C13 that the newly installed Cap is OK, measure ESR, confirm +ve lead is to Pin 5 of IC1.
The replacement cap was a brand new electrolytic capacitor 50v10uf Rubycon YXF

If YES, then you will have to replace IC1. $1.30 from China. We went through a lot of troublesome steps to confirm this.

So you are saying by the above, and my readings that it does indeed look to be that IC1 is at fault.

Where would be the best place to buy a new IC1 (ML4824)?

Thanks again for your time.

[Armadillo]

So you are saying by the above, and my readings that it does indeed look to be that IC1 is at fault.

Where would be the best place to buy a new IC1 (ML4824)?

Thanks again for your time.

Yes, you should replace the defective ML4824. you can get it from ebay in china. Suggested below, but please check your package type etc... I have not buy from them before.

http://www.ebay.com/itm/ML4824IP1-DIP-16-IC-Power-Factor-Controller-BIPOLAR-/322563116018?hash=item4b1a428bf2:g:-nIAAOSw~y9ZEspg

You can search around.

Edit; What do you mean by "Seems OK"?.

[Armadillo]

The capacitor C13 is for timing the Soft Starting of the TV.
Normally it is 2.2 uf because the charge current is really small from the IC.
I wonder why your schematic shows 10uf, no wonder the IC is short lived.

Now while your IC is on the shipment;

Can you try to install a 2.2uf 50V electrolytic capacitor [low leakage type] onto C13 and try again. If you are not sure about PC1S, temporary remove it from the circuit.
You can install back when the IC arrived.

See the schematic attached.

[wraper]

Before ordering ML4824, measure reistance between IC1 pin 5 and 10 to see if there is no low resistance. Also I suggest removing PC10S, if it does not help, also remove Q78 to ensure that nothing is preventing IC1 pin 5 from going hi.

[Mad Professor]

The resistance between IC1 pin 5 and 10, is not a stable reading but in the megaohm range.

I also removed PC10S & Q78, I still get the same 0.4v at pin 5 of IC1.

[Armadillo]

The resistance between IC1 pin 5 and 10, is not a stable reading but in the megaohm range.

I also removed PC10S & Q78, I still get the same 0.4v at pin 5 of IC1.

That should confirm defective IC1. Order and replace it. Any way to get it locally and quickly.?

We wait to hear the good news from you.   

[Mad Professor]

I would like to thank you all again for your replies, and helping confirm that IC1 (ML4824) was faulty.

I ordered a new replacement ML4824 from a UK eBay seller, and received it today.

After refitting the removed components for testing, and fitting the new IC, the TV fired into life, fully back up and working.

Thanks again