How do you troubleshoot this board? samsung hps4253 BN94-01081A

[NicoNico]

title is wrong the board below is what i am working on

How do I troubleshoot this board? PSU is putting out what seems to be the right voltage but relay is clicking on and off.

BN41-00694A

from Samsung hps4253

[tom66]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

A common fault with these is cold solder joints.
First check all output voltages and PS ON signal. If PS ON is fluctuating, the main board could be bad.

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

Thanks Tom I will try that and post results...

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

From PSU
VA's 65v
VS's 200v
Stnby 5v
VT 33v

From Main Board
CN101 pin 6 fluctuating it should be 18v
CN102 Normal

so is this PSU problem or Main Board problem? is there a way to turn on PSU then check Voltages?

Thanks Tom

[tom66]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

To check PSU, with PSON, you will need a 100 ohm ~ 470 ohm resistor, do you have one?

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

I do

[tom66]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

OK, locate PSON pin (it will be labelled) on power supply connector. Unplug the connector from the main board end. Connect the PSON to ground through the resistor. Then plug power in. All voltages should rise and become stable except Vs/Va. Also the relays should only click once or twice. To test Vs/Va, unplug PSU then run a second resistor (PSON still needs jumpering) from VSON to 5V standby (not ground!) When plugged in Vs and Va should rise to appropriate levels.

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

Ok will try that thanks again Tom

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

Connected with resistor powered on like you said and I connected the resistor to the high-voltage They check out. Can these boards be fixed? I would love to if it is doable also will be uploading video cause it turns on intermittently watch and see If it helps. I'll post it in a bit

[tom66]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

So, you do not get cycling voltages or relay? Not much that can be done re main board repair. You can check voltage regulators, but that's about it.

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

when I jump to ground PSON Relay Clicks on and stays on and voltages are there, then when I jump VSON to STBY 5v Vs are there.

How do I test regulators? or is there a post somewhere on how to properly test them... I have a Scope if that is easier. Thanks once again Tom

Nic

RetiredCaps posted this..
https://www.badcaps.net/forum/showth...est+regulators
7.1 Voltage regulators
-------------------------

Voltage regulators (U designation) can be bad. They can be shorted or output the incorrect voltage. The test described below only tests the former.

If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test voltage regulators "in circuit" for shorts by (power off and unplugged)

a) black on pin 1- red on pin 2 - record ohms
b) black on pin 1- red on pin 3 - record ohms
c) black on pin 2- red on pin 3 - record ohms

If any ohm reading is less than 30 ohm you might have shorted voltage regulator. Remove from circuit and repeat the tests to verify.

[NicoNico]

Re: How do you troubleshoot this board? samsung hps4253 BN94-01081A

http://www.youtube.com/watch?v=2WNLsJtrM7E Intermittently powers on and does this