Samsung SyncMaster LD220HD HDTV/Monitor - no power on

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

OK, can you post the link, please?

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

You will read the DC voltage with the TV powered on. See the link below on how to test and report the readings in proper format.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

OK, I see.

Should I be testing those three 3-pin regulators on the mainboard, next?

If so, do they need to be removed from circuit?

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Reading on number 9 (Inverter ON) is telling us that the main board is not sending the signal to turn on the inverter circuits.
Reading on number 1 (Backlights Dimming) is also bad.
So you do have problem on the main board since it is not lighting up the power LED, and also not sending the Inverter on signal or Dimming signal to the power supply board.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

On/OFF voltage isn't right... So its a defective mainboard.

Do you mean power board?

To me, it doesn't look like any power is getting to the mainboard.

[newtothis]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

On/OFF voltage isn't right... So its a defective mainboard.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Some better pics of the main board, I hope...

Retested with F301 still disconnected and with mainboard attached...

A slight difference in readings from the previous test, which was without the mainboard attached.

Readings on power board pins...

1. 0.00 to 0.02
2. 14.7 to 15.9
6. 1.7 to 3.0
7. 1.7 to 3.07.
8. 1.7 to 3.0
9. 0.00 to 0.01

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Ah, OK.

I won't have time to test again today, but should I be getting a constant voltage at pin 9, or just a quick burst?

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Oh, that is just a Common Cathode rectifier Diode, not voltage regulator.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

I was actually referring to the 3 pin rectifier D108, itself.

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

I do not see anything like SA101 by the D108 rectifier.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

There's also one on the power board at D108...

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

SA101 is the Gas discharge tube for the surge protection, it should not light up unless the voltage spike is really high.
I can see three 3-pin regulator ICs on the main board.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Pic of SA101, right above the power socket.

Also pic of mainboard. Tomorrow, I'll try to take a better pic and also the underside.

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

I do not know what SA101 is, if the main board is getting the voltages but no power LED indication , that will point to the problem on the main board. Voltage regulators on the main board will have to be tested next if that is the case.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

No power indicator LED light.

Will have to retest to check pin 9.

I did notice a flash from SA101 when powering on, though. Should it do that?

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

OK, when everything are connected together, report the voltage on pin "9 [ON/OFF]", it should change state when the power switch is activated. The power indicator LED is on at all?

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Isn't that what you did on post 14?

No, I didn't attach the main board. Sorry if I didn't make that clear.

I will try it shortly with the main board, plus everything else attached, but the fuse still desoldered and see if it makes any difference.

See post 15, with regard to the voltages with the fuse in place. They were all the same, except pin 2 [15v] with was reading slightly more stable at ~14.3v to 14.6v.

[budm]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

"OK, this morning, I have desoldered one pin of F301, powered up the board, and taken the following voltage readings...

The big cap reads 336v
F301 disconnected [if I'm testing it correctly] 0.0 to 0.01 on setting 20 DCV
The voltages across the the connector pins...
1 [B-DIM] 0.0
2 [15V] 13.5 to 14.5 unstable
3 GND
4 GND
5 GND
6 [5.2V] 5.0 to 5.2 unstable
7 [5.2V] 5.0 to 5.2 unstable
8 [DCR] 0.0
9 [ON/OFF] 0.0"
"Is it safe to power up with the fuse out of circuit?"
Isn't that what you did on post 14? So now you will need to have the main board connected to the power supply board to see if the you can turn the monitor on and off (power LED goes on and off). The fuse can be left off, it is for feeding the voltage to the inverter circuits. I am trying to find out if the main board will response to power on/off switch. Report the voltage readings in the same format as above when you test with all the boards connected.
I still did not get the answer about the voltage on the pins when the fuse was in place in post3. What I am trying to find out is that if the fuse is connected then there is no voltage at the pins or not, then the fuse is lifted then you get the voltage, that will tell me it has shorted circuits in the inverter section that causes the power supply to shut down. You are getting voltage now when the fuse is lifted, so do you get the voltage if the fuse is back in place? That is why I asked the question in post 3 since I have no idea if the voltages are present or not from the beginning.

[oddbodd]

Re: Samsung SyncMaster LD220HD HDTV/Monitor - no power on

Is it safe to power up with the fuse out of circuit?