CTM 644 problem

[FRAGKI-2012]

Hello I need help to repair my monitor is complete dead any suggestions ...?
I have already open I test the switch and the fuse and seems ok I m thinking for the transformer that has inside the 8142006T it is possible? To find somewhere ? Is anybody to help me?
Thanks in advance!

[Bryce]

A couple of questions:

- does it make a whining sound when it's turned on?
- Can you feel static charge on the screens glass when it's on?
- If you turn out all the lights, does the screen glow when powered?

Bryce.

[FRAGKI-2012]

hello I m very glad to hear from you !!!!
the monitor is completed dead no noise no static no glow !!!!
any ideas ?

[Bryce]

Hi Fragki-2012,
        here's what you need to go through:

Check voltage across CP501 (Connector coming from input transformer). You should be getting an AC voltage across pins 1 and 3 and across pins 2 and 4, both should give you readings 22VAC or less, but if the transformer is fried, you could be getting 230VAC here, so try to avoid touching the pins until you are sure what's on them. If it's 0V, the transformer has died, but the rest of the monitor is probably fine. If it's 230VAC or anything above 50VAC, then the main PCB probably hasn't survived. If all is ok, then you need to start checking the DC on the PCB. Check C509 (big 4700µf capacitor) and C510 (big 3300µf capacitor): C509 should have about 10 or 11V across it's pins, C510 should have about 18V across it's pins. If either voltage is missing completely, the the recifier may have failed. If the have a much lower voltage (less than 7VDC) then you probably have a short circuit somewhere on the PCB.

Bryce.

[FRAGKI-2012]

thank you very much but the transformer is dead 
where I can find one or similar one

[FRAGKI-2012]

so I need tow transformers from 220v to 22volt?? how many amperes??

[Bryce]

If it's dead yes, but it's only one transformer with an (almost) centre tap. The outer taps would give you about 30VAC, the Centre tap divides this, so that from one outer to centre gives 18 /19VAC and the other probably gives 11 / 12VAC. These aren't standard values for transformers, so it may be easier to use two transformers to replace this one.

Bryce.

[FRAGKI-2012]

you know where I can find a similar one or tow so I can replace??

[Bryce]

Is it definitely dead?

No idea where you'd find one. 12 / 18V is available, but not at the amount of amps this thing needs.

Bryce.

[FRAGKI-2012]

it possible to know exactly the output so I can search for a similar ? the one output is 12 vac? and the other is 30 vac ? and the other 22 ? and one common? im confused now it output 3 different voltages?

[FRAGKI-2012]

yes it takes 220 but in output is 0 value

[Bryce]

No it will be called 200V to 12VAC + 18VAC(The actual values of the CPC part is 10.3V and 18V after the rectifiers, so the transformers real values are probably 19V and 11V). The 12VAC ouput needs to be able to supply at least 3A to 4A and the 18VAC needs about 2A.

This won't be easy to find.

Bryce. 

[FRAGKI-2012]

you know any supplier that I can order online? any link ?

[Bryce]

No, I've checked my sources and nobody has one. I also wouldn't recommend a chinese one for such a safety critical part.

Bryce.

[FRAGKI-2012]

i find this :http://uk.rs-online.com/web/c/power-supplies-transformers/transformers/switch-mode-power-supply-smps-transformers/#esid=cl_4294967294,cl_4294513245,cl_4294513227,cl_4294956957,cl_4294957383,cl_4294513229
is any from this that I can fit???

[TFM]

Thanks for the manual. I will do that tests for my broken 644 too. 

[Bryce]

i find this :http://uk.rs-online.com/web/c/power-supplies-transformers/transformers/switch-mode-power-supply-smps-transformers/#esid=cl_4294967294,cl_4294513245,cl_4294513227,cl_4294956957,cl_4294957383,cl_4294513229
is any from this that I can fit???

No, they are tiny Flyback transformers for switch-mode PSUs. The type you're looking for is going to cost about €50 just from the copper content alone.

Bryce.

[CraigsBar]

New monitor time methinks.

[FRAGKI-2012]

the problem fix it my monitor is alive i replace the stk7308 and the resistor 5w 5,6ohms and the diode 30d1 and it works fine I m very lucky as I have a second monitor that works an a measure each part with the other and I find the solution very fast!
now I have 2 monitors  the test for the monitor pass successfully as it works 4 hours continuously whit any other problem!!

[Bryce]

Congratulations. But that also means the transformer was live the whole time. Lucky you kept your fingers off it.

Bryce.

[FRAGKI-2012]

Thank you !
The transformer it was ok all the time !
But I'm wondering if is not where I can find similar one ...

[Bryce]

The cheapest solution would probably be to use two small single transformers with 220V -> 12V and 220V -> 18V which should be much easier to find.

Bryce.

[Stephan]

Sorry for posting in this old topic. i have the same problem like FRAGKI-2012. If i turn on the monitor, it does absolutely nothing, only the 12V output is working and it make a whining sound. i have checked the voltage across CP501 (in my manuel its called L501). I got 230V. Does this means that the PCB is fried?

[Bryce]

Most likely the HT Transformer (LOPT) has died or the capacitors associated with it. Unless you really know what you are doing, I wouldn't advise trying to fix this yourself.

Bryce.

[YuT666]

Hi,

similar problem and my question is - where is the CTM644's fuse? I looked a t the shematics, but i can't find a fuse ...

Thanks.