T240 Monitor Backlighting Issue

[aster1x]

Re: T240 Monitor Backlighting Issue

My problem is that the monitor produces a naty smell as if the board has overheated and burned. My transformer has visible plastic distortion due to heat. The monitor is working perfectly but the back panel at the are of the power supply is warmer than the other side and it smells badly.

I believe the transfmer has arched and overheated. Shou I replace it?

So far I have realized that the power supply boards IP-58155A have the TM-0918 inverter transformer and their power supply cord plugs perpendicular to the board.

At the begining of the thread there is another power supply board which I can not tell the part number, its power supply cord plugs in parallel to the board and they use the TM-10160 inverter transformer.

What is the difference between the two inverter transformers TM-0918 and TM-10160 ?

Both part numbers are available on ebay.
Are they compatible to each other?

[flying welshman]

Re: T240 Monitor Backlighting Issue

Sorry for the thread necro, but i just wanted to thank everyone in this thread. I had the same problem as the op and this thread told me everything i needed to know to open up the monitor, test components, find that my problem was a faulty transformer and replace it. So now instead of however much it would have cost to get it repaired or having to buy a new monitor, i am only down £20 and am the proud owner of a new multimeter, new soldering iron and a fully working monitor.

[lizzrd]

Re: T240 Monitor Backlighting Issue

thanks sell door, to be honest i am just getting back to this project...

[selldoor]

Re: T240 Monitor Backlighting Issue

We really need to know if when you switch it on NOW does the screen flash at all?

The link to the cfl is in budms signature 2 posts above.

Oh ho! you have managed to hide a fuse from us. Did you check the White one F102 in the middle of the board- Hiding behind the heatsink is a green torpedo fuse f 301 to test as well.

Test fuses - No power to board meter on ohms 200 one probe to each side of fuse
should be same as holding the probes together.
Next test after that is to turn on the power and test the voltage at each side of the green fuse with the black probe on chassis ground.

[lizzrd]

Re: T240 Monitor Backlighting Issue

thanks again for the replies, i did not take the panel apart farther. I saw a reference about the test lamps ,clf bulbs ?, so i'll search that out.
i will keep those two yellow caps in mind...

[budm]

Re: T240 Monitor Backlighting Issue

I talked to the lady friend that gave this to me. She said it turned on for a minute then went blank. Seems longer than the OP and others. ?
I see no visual wire or connection /tubes burns...

So you took the panel apart to get the lamp assemblies? If I were you I would use two test lamps to find out if you have board problem or lamps problem.

[stj]

Re: T240 Monitor Backlighting Issue

the large yellow cap near the heatsink looks like the top has started to dome slightly.

[lizzrd]

Re: T240 Monitor Backlighting Issue

I talked to the lady friend that gave this to me. She said it turned on for a minute then went blank. Seems longer than the OP and others. ?
I see no visual wire or connection /tubes burns...

[budm]

Re: T240 Monitor Backlighting Issue

So the backlights did come on for seconds and then black out? Then it may be bad lamps, bad MOSFET (the SMD with 5 legs on the bottom and big tab on top), bad inverter power supply section, bad BL_ON signal, ETC.
Can we see staright shot pictures of the top and bottom side of this Power supply-inverter board. It may be time to make two test lamps.

[budm]

Re: T240 Monitor Backlighting Issue

1.006 K ohms, and 1012 K Ohms? If they are, then they are good.

[lizzrd]

Re: T240 Monitor Backlighting Issue

I scraped on the side of the pins and kind of pushed the points of the probes in a bit.
Got readings of 1.006 and 1.012. Don't know if it matters, this board is disconnected from the other board of the unit.

[budm]

Re: T240 Monitor Backlighting Issue

The pin out of the windings in my post 49 is correct, so you may have to clean of the flux or resolder the pins of the transformer and try reading the resistance again.
It has the same pin out as this one:
http://s807.photobucket.com/user/bud...tml?sort=3&o=3

[selldoor]

Re: T240 Monitor Backlighting Issue

Try the test again resistance should be around 1000ohms
Check you have the meter selector in the correct position - it goes all the way round on mine so
200ohms look pretty much the same as VAC600

Also try scratching the top of the solder joint with the probe

[lizzrd]

Re: T240 Monitor Backlighting Issue

thanks for your reply Bud,

[budm]

Re: T240 Monitor Backlighting Issue

Can you post the pictures of the top side of the board and the P/N as printed on the transformer so we can look for the pin out of the transformer?

[lizzrd]

Re: T240 Monitor Backlighting Issue

yes , sorry for the timing of my posts , i have 3 kids here, so kept busy...

[budm]

Re: T240 Monitor Backlighting Issue

What scale do you set the Meter's Ohm mode to, 2K?

[lizzrd]

Re: T240 Monitor Backlighting Issue

so the black to pin 1 and red to pin 2 , shows it reading up to 1. and the same for 3+4...
i also looked at the solder with a mag glass and they seem ok , like the other solder points.
I do not see any discolored points or bad caps.

[budm]

Re: T240 Monitor Backlighting Issue

Oops, set your meter to 2K Ohm scale and take the reading between pin 1 and 2, then pin 3 and 4. NO POWER to the unit of course. The solder joints look like they have some ring (hair line crack) around the pins.
For examples:
http://s807.photobucket.com/user/bud...?sort=3&page=1

[lizzrd]

Re: T240 Monitor Backlighting Issue

I am a total beginner. 1+2 , 3+4 is what i thought was to be checked. But the board being different puzzled me, still does. Why would they be different ? Would you tell me what looks bad about those 4 points ? I only have a multi-meter, how/what could i check for the whole board ? I could take this board to a PC repair place that did some solder work for me last month if i am not 'able' to. sorry for all the questions...