samsung PS42C450B1WXXU

[tom66]

Re: samsung PS42C450B1WXXU

Just an overall shot of the bottom of the board.

I think you probably got a dud board, but I'm not sure. If you have a scope, you could test the scan voltages.

[lakey35]

Re: samsung PS42C450B1WXXU


There you go.

[tom66]

Re: samsung PS42C450B1WXXU

No - bottom of the board. Usually green.

[lakey35]

Re: samsung PS42C450B1WXXU


Is this what you mean?

[lakey35]

Re: samsung PS42C450B1WXXU

have just checked Va and Vs again on power board while Y board is out of tv and voltages are holding now.
So am looking at replacing Y board again.

[tom66]

Re: samsung PS42C450B1WXXU

Yes. I've highlighted some components.

Blue circled components = probably diodes. Use your meter on the diode range. Check them one way, and the other. You should get ~0.5V one way, and infinite the other.

Red circled components = Check all pairs of two pins for short circuits using the ohm range. You should find no continuity between any two pins.

[lakey35]

Re: samsung PS42C450B1WXXU

d5004 441 both ways
d5003 441 both ways
tested with diode range
q5003 short
q5007 short
q5008 short
tested with ohm range

[tom66]

Re: samsung PS42C450B1WXXU

d5004 441 both ways
d5003 441 both ways
tested with diode range
q5003 short
q5007 short
q5008 short
tested with ohm range

Are those all the transistors? It would be strange for all to be shorted. Could you list which pins are shorted? (Typically drain-source shorts, or drain-gate.)

441 both ways indicates a problem with measuring in circuit.

You may have to desolder each MOSFET and test it individually.

Or you could send the board back as faulty as it looks a lot like it is.

[lakey35]

Re: samsung PS42C450B1WXXU

I will desolder the components tomorrow and test them again, but I have been offered another tested board for £15 so will buy that and see what happens.
Can the buffers blow the new board or should it be ok?

[tom66]

Re: samsung PS42C450B1WXXU

I will desolder the components tomorrow and test them again, but I have been offered another tested board for £15 so will buy that and see what happens.
Can the buffers blow the new board or should it be ok?

Yes, a bad buffer can damage a Y board.

I would advise you change both at the same time as the buffers may be causing all of your problems. Seems to be the only part you haven't yet changed!

[lakey35]

Re: samsung PS42C450B1WXXU

I have changed them aswell though lol. Managed to get a full set of boards for it but they were untested but for £60 the lot was worth the gamble lol

[lakey35]

Re: samsung PS42C450B1WXXU

Is there anyway I can test the y buffer board without connecting it to the y board?
The buffer boards i have are both pcb no:LJ41-08594A.
Have got the new y board but dont want to risk blowing it without testing the buffers.
Thanks guys

[tom66]

Re: samsung PS42C450B1WXXU

Is there anyway I can test the y buffer board without connecting it to the y board?
The buffer boards i have are both pcb no:LJ41-08594A.
Have got the new y board but dont want to risk blowing it without testing the buffers.
Thanks guys

Post a picture of the board - a multimeter ohm test can find most (but not all) failures.

[lakey35]

Re: samsung PS42C450B1WXXU



heres a pic of the board
Had to get one of net cause camera battery died but is the same board

[lakey35]

Re: samsung PS42C450B1WXXU

i know the pin out of the far right top connector is
1:gnd
2:gnd
3:reset
4:5v outl
5:gnd
6:gnd
7:le-2
8:oc2-a-2
9:oc2-b-2
10:os1-2
11:clk-2
12:gnd
pin1 is on the right

[tom66]

Re: samsung PS42C450B1WXXU

Plug buffer into sustain board.

Connect sustain board power.

DO NOT TURN ON TV!

Test resistance between each red arrow (any pin) and ground.

***
Actually, can post a close up pic of the connector on your board? I can't see if the sustain voltage is on those pins or if they are data signals.

[lakey35]

Re: samsung PS42C450B1WXXU

far right connector


middle connector


left connector

[tom66]

Re: samsung PS42C450B1WXXU

Okay, test this pin to TV's case, whilst connected but not turned on.

Then can you get a picture of the bottom of the buffer board?

[lakey35]

Re: samsung PS42C450B1WXXU

have tested that pin and i get o/c is that correct?

[tom66]

Re: samsung PS42C450B1WXXU

have tested that pin and i get o/c is that correct?

That's fine. Can you post a pic of each connector and both sides of the board?