Samsung 215tw still dead :(

[sabre504]

Re: Samsung 215tw still dead

I would suggest you assemble the boards back onto the panel
With the mains lead plugged in check the voltages on the lead that connects the psu to the main board ( record them) .

Then power up the monitor checking the voltages on start up (record them)Wait for the back lights to go out and check the voltages again this way you can see if the voltages are going over or under what is needed to supply the logic board to far out of spec and you will get white screen .

Also test the small smd fuse on the lcd panel .

You may have to sort your backlight problem before you tackle another problem that could well be being caused by the first problem (if that makes sense)

[digge]

Re: Samsung 215tw still dead

While i do agree that the transformer is semi bad, and would need to be replaced in the long run. Would that really cause nothing to appear on display if the backlight comes on?

Im asking cause if it turns out there are more problems, like others have had before with corrupted firmware or similar, then it wouldnt be worth getting another transformer unless i could get my hands on a working firmware first.

EDIT:

Im not sure if the backlight part is separated enough from the rest of the logicboard so that it will feed picture no matter if the backlight works as intended or not. If thats the case i would like to solve the totally black picture first, and then after that fix the backlight.

Just want to make sure im not sinking a lot of money into something i eventually wont be able to repair.

[jetadm123]

Re: Samsung 215tw still dead

Looks like there is a scorch mark under one of the transformers

Great catch by sabre504, which reinforces the reason why members need to see photos of YOUR board. Looking at someone else's board would have never revealed the scorch marks.

[PlainBill]

Re: Samsung 215tw still dead

PlainBill suggests that these inverter transformers should be within 3% of each other. Details at

https://www.badcaps.net/forum/showpo...7&postcount=18

So 900 x 0.97 = 873 ohms.

This suggests the inverter transformer is out of spec and bad.

And the signs of overheating would confirm that.

PlainBill

[alexanna]

Re: Samsung 215tw still dead

Thank you,
I did misunderstand; there is enough difference in your ohm readings on the one transformer to cause a problem.

[retiredcaps]

Re: Samsung 215tw still dead

On those pins i measure about 900-910 ohms on all but the one where the suspected scorch is, that one measures 855ohms.

PlainBill suggests that these inverter transformers should be within 3% of each other. Details at

https://www.badcaps.net/forum/showpo...7&postcount=18

So 900 x 0.97 = 873 ohms.

This suggests the inverter transformer is out of spec and bad.

[sabre504]

Re: Samsung 215tw still dead

Turned out the same on mine
Either bad wiring on the CCFL have caused transformer to start to fail or
vice versa .
Without a spare tube the only option i can suggest is a new trans or a good second hand one

[digge]

Re: Samsung 215tw still dead

As i remember on mine and on the neovo i did (used these transformers)

The 2 yellow areas were the secondaries (Think)

On those pins i measure about 900-910 ohms on all but the one where the suspected scorch is, that one measures 855ohms.

[Th3_uN1Qu3]

Re: Samsung 215tw still dead

Supposed to be ~1k. Either your transformers have failed open (but that's a no since your backlights work) or they have a different pinout.

[digge]

Re: Samsung 215tw still dead

Good focused pictures are ALWAYS a help. In the photo, measure resistance across the points outlined in yellow. You may be able to do your measurements on top of the board, otherwise you'll have to scrape off the white adhesive. Also, measure the other 3 transformers on the other side the same way.

Since you say there was a scorch mark in the upper CCFL assembly, I'm assuming the wiring was shorting out? If the transformer powering that assembly checks good, then check all components connected to that transformer for shorts.

If you have a spare ccfl, then try substituting it for the one that was shorting out.

Measured all of them, yellow marked in your pic. Gives no connection on any of them. My dmm only goes to 20M but im guessing its not supposed to be higher then that?

Dont have any extra tubes to try with, but at least the short should be fixed since my fix made the failsafe stop turning the backlight of at least?

[sabre504]

Re: Samsung 215tw still dead

As i remember on mine and on the neovo i did (used these transformers)

The 2 yellow areas were the secondaries (Think)

[sabre504]

Re: Samsung 215tw still dead

Looks like there is a scorch mark under one of the transformers

[jetadm123]

Re: Samsung 215tw still dead

Good focused pictures are ALWAYS a help. In the photo, measure resistance across the points outlined in yellow. You may be able to do your measurements on top of the board, otherwise you'll have to scrape off the white adhesive. Also, measure the other 3 transformers on the other side the same way.

Hmmm... looking a little more closely, it looks like one of the test points (the one without adhesive over it) MAY NOT be connected to anything. Try putting one test probe on the point with adhesive and test the other pins of the transformer with the other probe. Pin 1 (lower left) of the transformer appears connected to ground.

[digge]

Re: Samsung 215tw still dead

Please explain: dose your monitor power led indicate a signal [green or blue light] when the computer is posting, and it indicates no signal [amber led ] when it gets into the operating system? Or did I misunderstand your problem?

Didnt try it during post yet. What i tried is not connected to compute = always blue and connected to computer = always blue i think, i will restest and make sure. Difference was that when connected to computer the backlight would go of quite soonish, while not connected it would stay lit for much longer.

[retiredcaps]

Re: Samsung 215tw still dead

Mine have only 5 pins total.

I *think* the secondaries on this inverter transformer are the two feeding into the blue caps.

[jetadm123]

Re: Samsung 215tw still dead

That is not the same ones i have on my board. Mine have only 5 pins total.

Ill attach more pictures below, hope that helps any.

Good focused pictures are ALWAYS a help. In the photo, measure resistance across the points outlined in yellow. You may be able to do your measurements on top of the board, otherwise you'll have to scrape off the white adhesive. Also, measure the other 3 transformers on the other side the same way.

Since you say there was a scorch mark in the upper CCFL assembly, I'm assuming the wiring was shorting out? If the transformer powering that assembly checks good, then check all components connected to that transformer for shorts.

If you have a spare ccfl, then try substituting it for the one that was shorting out.

[alexanna]

Re: Samsung 215tw still dead

Please explain: dose your monitor power led indicate a signal [green or blue light] when the computer is posting, and it indicates no signal [amber led ] when it gets into the operating system? Or did I misunderstand your problem?

[digge]

Re: Samsung 215tw still dead

Mine would stay on for a while then flicker and shut off

Do a resistance test between pins S1 and S2 should be approx 950 ohm

See pics

That is not the same ones i have on my board. Mine have only 5 pins total.

Ill attach more pictures below, hope that helps any.

[ryankam]

Re: Samsung 215tw still dead

Got this monitor from somone who had evidently tried to repair it. The caps on the powerboard were already replaced with Sanyo WX.

I had a customer give me two identical monitors that had caps replaced by them. They turned out to not have all been replaced. I took caps off one by one and replaced them until my monitors powered back up. Turned out to be the startup caps on the 5v standby.

Also I have a Hyundai 24inch monitor with similar issues to yours. I have not checked if it is due to a short at all. But I know those hyundai's have logic board issues.

[sabre504]

Re: Samsung 215tw still dead

Mine would stay on for a while then flicker and shut off

Do a resistance test between pins S1 and S2 should be approx 950 ohm

See pics