Samsung Syncmaster 245B

[retiredcaps]

Re: Samsung Syncmaster 245B

I forgot to mention that on the logic board there should be a label for on/off. It should be written on the connector somewhere. Or it could be labeled on the power board?

This voltage will be 0V DC when off and probably > 3V DC when on. So when you press the on/off button, this pin should change in voltage from 0 to 3V DC.

[retiredcaps]

Re: Samsung Syncmaster 245B

The voltage readings on the logic board look good.

On the power board, you are not getting 24V or 5V.

What is the DC voltage across the main filter capacitor? Hint: This is very high voltage and measuring it when hungover may not be a good idea.

It should be 220V AC x 1.414 or roughly 311V DC. So put your multimeter on something higher than 400V DC.

[Rhodri2311]

Re: Samsung Syncmaster 245B

Ok slightly hungover following the Welsh rugby loss but should be fine to tinker today Is there anything else I can check or you can suggest I try? Cheers!

[Rhodri2311]

Re: Samsung Syncmaster 245B

Balls read the instructions and had my red and black wires plugged in the wrong way round. Touching the wires gives a result of 0.03 once it's settled down.

Resistence across the fuse seems to be 0.06.

The voltage regulator is: J162 953-18

[retiredcaps]

Re: Samsung Syncmaster 245B

With the pins at the top and left to right the results were: 1.8v, 0, 2.9v

What is the part number of the voltage regulator?

[retiredcaps]

Re: Samsung Syncmaster 245B

Let's make sure your multimeter is working right first.

1) Put your multimeter on 200 ohms (if manual). Touch the 2 probes together. What is the reading?

2) For the fuse, you should be measuring ohms with power off and lcd unplugged. A good fuse should read under 1.0 ohms.

[Rhodri2311]

Re: Samsung Syncmaster 245B

Ok some results! First of all I tried testing the logic board fuse, but couldn't get a stable reading at all. It seemed to constantly fluxtuate from 0 to anywhere up to 100.

Next the volatage regulator on the logic board. With the pins at the top and left to right the results were: 1.8v, 0, 2.9v

The DC converter: (pins at top left to right again): 0, 3.3v, 0, 3.33v, 5.2v

And the power supply board:
+24 = 0.03v
SB = 5.23v
5.4v = 0

I'm guessing that's not a sign of a healthy board =/

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245B

That meter will do fine. And yes "ground" is just the metal surround on the screw holes.

[Rhodri2311]

Re: Samsung Syncmaster 245B

Probably won't get a chance to look at it tomorrow, but should be able to have a fiddle with it wednesday night hopefully, I'll grab as many testings as I can then. Is the ground screw on the logic board just the metal surround on the four screw holes or will I need to earth it to something?

[jetadm123]

Re: Samsung Syncmaster 245B

I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages? Anything I'd need to be careful of? Because I think the ground screw goes through the metal chassis, but it'll be impossible to get to the chip when it's attached to that.

Attached a diagram of the connections on the power supply board.

If you're going to measure voltages off the logic card, then you should reassemble the boards, since the logic card gets it's power from the power board. Also, with power off and meter set to resistance, check the fuse (circled in photo) on the logic card.

[Rhodri2311]

Re: Samsung Syncmaster 245B

I frequently switch parts out of several PC's and ment to pick one up few times to make fault finding easier so about time I picked one up!

Would this be sufficient? http://www.maplin.co.uk/ut30b-palm-s...ltimeter-46498

Thanks for all the help.

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245B

A 830B is under $10 and is good for having around the house even if you only use it once a year.

[retiredcaps]

Re: Samsung Syncmaster 245B

I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages?

If you don't plan on doing many electronics repair, borrow a multimeter from a friend.

You have to all the boards connected. You don't need to put the case on at all.

The voltages on the logic card are generally less than 5V DC.

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245B

A basic 830B multimeter should suffice for now. Look for a UNI-T branded one, those are decent compared to the nonames.

Yes you will have to wire everything together but that doesn't mean they have to go in the same places. Put some plastic or cardboard over the back of the LCD panel and put the power supply and logic board on top of that. That way you can measure stuff without assembling the whole thing. For more complicated measurements you solder a wire to the spot then power the monitor... but at least the main connectors should be accessible without the need for such stunts. You don't have to wire the ground lead of the plug now.

Black lead of multimeter always goes to the nearest GND. Red lead goes to the circuit you are testing. First things to check are the voltage rails which are SB, 5.4v and 24v. SB is usually 5 volts.

[Rhodri2311]

Re: Samsung Syncmaster 245B

I'll need to pick up a multimeter (terrible I don't have one to be honest), would I need to reasemble the bulk of the monitor before attempting to measure the voltages? Anything I'd need to be careful of? Because I think the ground screw goes through the metal chassis, but it'll be impossible to get to the chip when it's attached to that.

Attached a diagram of the connections on the power supply board.

[retiredcaps]

Re: Samsung Syncmaster 245B

1) See attached pic.

2) The yellow component is a voltage regulator. The part number might be something like AS1117-18. The suffix, 18, indicates the DC output voltage.

With power on and lcd plugged in, set your multimeter to 20V DC (if manual ranging). Use a ground screw on the logic board for your black probe. Your red probe will go on each pin (one at a time) on the voltage regulator. Report the findings.

3) The red component is a DC/DC converter. The datasheet is at



Refer to page 2 and see the diagram labeled TO263-5L.

Again with your multimeter set on 20V DC and your black probe on a ground screw, put your red probe on all pins (one at a time) and report voltages.

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245B

That looks like a fairly solid board so it could prove difficult to fix. You have a couple connectors on that power supply. The white ones on the edge of the board. In the pictures they are obscured by the caps, could you please list everything that's written above the connectors? That way we can give you hints on what you can check.

Also have a digital multimeter handy. That comes without asking usually but there are some folks that don't actually have one at the moment they post here.

[Rhodri2311]

Re: Samsung Syncmaster 245B

And a few more.

[Rhodri2311]

Re: Samsung Syncmaster 245B

Ok here are a few photos, wasn't really sure what was important so if you need anything else I'll grab a photo of it.

Cheers!

[Th3_uN1Qu3]

Re: Samsung Syncmaster 245B

You only need to discharge the big one.