Samsung SyncMaster T240 - 2 seconds then black problem

[Scenic]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

@preface: If it's a different model monitor, you might be better off opening a new thread for it.
That would also help others to find it without having to dig through a multi-page thread for a different monitor to find the relevant posts

[preface]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

model: 2233bw -
I have a 2 seconds then black problem after replacing an AP4506GEH ((Push/Pull Mosfet dual channel N/P) to-242 SMD 4 + 1 legs.)

With 2x TO-220 packaged MOSFET with similar ratings (30v rdson 0.28ohm/0.36ohm) and connecting the D legs together to make a dual mosfet.
The very reason i did go this desperate path is because couldn't find AP4506GEH or anything similar (several mosfets with same package mentioned in this forum) in the Thai semiconductor market.

The least is that the MOSFET tweak did work. However, I will post photo of the charred board and circuit pattern around the AP4506GEH, and offcourse the driver mosfet is burnt as well.

After reading the above posts, I can only think of the transformer gone bad. But isn't there any way to revive this end transformer? lets say by chilling it in a freezer and injecting epoxy glue to it afterwards? i saw some aircon engineers did it with such coils here in thailand.

My only releive is that it does light up for 2 seconds. I reflowed many points and changed 2 capacitors..

Still have to measure the transformer. Anyone know where i can buy this?

I'll up some pics tommorow. Cheers!.

[PlainBill]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I have the same issue, replaced 6 caps and transformer t301, no luck, any other suggestions?

Retiredcaps has written an excellent troubleshooting guide for this problem. It's been revised several times, the latest version is at the end.

PlainBill

[nonenon]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I have the same issue, replaced 6 caps and transformer t301, no luck, any other suggestions?

[dribbles]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

All good guys.
If anyone has this problem in the future, it was the transformer. Unsoldered, resoldered the new one,
put it back together, All is well

[dribbles]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

Mine ended up having a bad main board. The processor chip got hot to the touch and after changing the board, it was 100%. Good luck!

As in the whole power board?

Or the other board thats in the case?

Cheers

[waitery]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

Mine ended up having a bad main board. The processor chip got hot to the touch and after changing the board, it was 100%. Good luck!

[dribbles]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

Sorry to bring up an older thread. But has anyone found a solution to this?

Burn marks in the same place on mine, except my monitor is a T260, but same looking board.
I have resoldered most of the major components hoping that might fix the problem.

But same 2 seconds on then off.

I have a new transformer on the way, thats the next step.

Other than that, all the capacitors look ok, doesnt mean that they are though.

Cheers
Dribbles

[PlainBill]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

So, I went ahead and was testing the 15 volt line. W/O the main board connected, I get 15.27vdc and it is stable. I connect the mainboard and it falls down to 14.90vdc and then the power cuts out. The voltage drop is causing the power supply to quit. After this happens, it just cycles.

PlainBill, can you help me troubleshoot?

I can try. The first step is standard - I want clear, well lit pictures of the top and bottom of your power supply. One of each, taken from direcly overhead, please. A minimum of 1000 x 1000 pixels, please, and attach them using 'Manage Attachments' - below the text entry area.

Also, a brief summary of what components you have replaced, as well as the brand (and series) of the capacitors currently in the board.

PlainBill

[waitery]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

So, I went ahead and was testing the 15 volt line. W/O the main board connected, I get 15.27vdc and it is stable. I connect the mainboard and it falls down to 14.90vdc and then the power cuts out. The voltage drop is causing the power supply to quit. After this happens, it just cycles.

PlainBill, can you help me troubleshoot?

[PlainBill]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I too have the same board with the same scorch mark in the same area. I went ahead and resoldered the jumper and purchased a new inversion transformer, but even after installing the new transformer, I am getting inconsistent power to the screen.....two seconds on, then off, four seconds on, then off, etc. It feels like a cold solder joint that needs to be reflowed. Plain Bill, what do you think>

It could be a loose solder joint, or a loose wire to a CCFL, or a leaky diode.

PlainBill

[waitery]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I too have the same board with the same scorch mark in the same area. I went ahead and resoldered the jumper and purchased a new inversion transformer, but even after installing the new transformer, I am getting inconsistent power to the screen.....two seconds on, then off, four seconds on, then off, etc. It feels like a cold solder joint that needs to be reflowed. Plain Bill, what do you think>

[PlainBill]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

This site is a god send, very glad I found it. It's been very helpful to me (a noob at this.. But eager to learn )

I also have the same thing, scortch marks on the topside and underside of the board around the transformer (pics attached).

After reading this thread, I plan on resoldering the jumper and replacing the transformer. Would/should I do the caps too?

I'm slightly lost in part numbers now and I'm unsure of which transformer to get, what did you go for, Art?

Any help is massively appreciated!

Thanks.

When faced with several alpha-numeric strings, Google each of them. TM10160 brings up a number of hits.

PlainBill

[Foo56]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I have the same symptoms and the same burning around the transformer. I replaced the transformer for $8 on ebay and the monitor is working again. Can anyone else verify this fix?

This site is a god send, very glad I found it. It's been very helpful to me (a noob at this.. But eager to learn )

I also have the same thing, scortch marks on the topside and underside of the board around the transformer (pics attached).

After reading this thread, I plan on resoldering the jumper and replacing the transformer. Would/should I do the caps too?

I'm slightly lost in part numbers now and I'm unsure of which transformer to get, what did you go for, Art?

Any help is massively appreciated!

Thanks.

[art1351]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I have the same symptoms and the same burning around the transformer. I replaced the transformer for $8 on ebay and the monitor is working again. Can anyone else verify this fix?

[PlainBill]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

can some one share service manual for samsung t240? thanks

Here's a link.

PlainBill

[johnnyto1979]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

can some one share service manual for samsung t240? thanks

[uwi_u]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

I should Mention, that I got the whole service-Manual for that monitor. Unfortunately, the PSU isn't described in there....

PS: I'm from germany. So please excuse my bad writing....

[uwi_u]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

Hi there!

Sorry for capturing the Thread, but I've got a slightly different Problem with my T240.

I got it with Description "Sometimes turns off". When I got it, I noticed that it takes a while before the Monitors Backlight will turn on. But then, the backlight flickered. I opened the case and got an Rev 1 PSU. I measured the Secondary Inverter-Coils. 1060 Ohms each (between 1x and 2x respective between 3x and 4x), ~330kOhms between the different coils(between 1x and 3x, respective between 2x and 4x). So i guess, the Inverter is still functional and ordered a set of Caps (low ESR). Soldered them in and no change happened :-( . Could it be due to the highVoltage-Caps on the Sense-Lines(xnF, 3kV)?


Inverter input side
--------------------------------
|xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx|
|xxxxxxxxxxInverterxxxxxxxxxxxxx|
|xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx|
|xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx|
--------------------------------
1x-------2x-----------3x------4x Outputpins

[DUCE]

Re: Samsung SyncMaster T240 - 2 seconds then black problem

Quite true PlainBill.This basic fact holds true across most engineering disciplines, be it electrical or mechanical. I used to design industrial dust collectors and the quote my boss gave me is "its not a matter of if they will fail but when". Electronics is a weak spot for me because I have focused on mechanical and CAD work most of my life. The electrons knowledge I have gained is frighteningly small considering how often I have to rely on electronic devices. I am attempting to change this now (at 40 no less).

So what has got me stumped on this board is finding another inverter transformer that will be compatible. Maybe buying a replacement as the other poster here did is my only option. Seems a waste but I am swinging in the dark unless I can find parts.