help for a CMT-640

[emilen72]

hi, I'have got this monitor some day ago... It was in a bad condition, all dust into the case, over the mainboard... I have clean it and connect to my 464... the 464 is powerd well (the led is on and the keyboard sound came out)... but the screen remain black... smoke does not exit, heats from the back... can you help me in what step to do for  try repair it?


many thanks in advance

[Bryce]

Is the HT working? Can you feel a charge on the surface of the glass when it is turned on?

Bryce.

[emilen72]

I think so... because when power-on it, I fell the classic sweeezzz of CRT monitor or TV

[Bryce]

Have you "twiddled the knobs" to make sure they aren't full of dust too?

And is it a completely dead screen, or is there a scanline, just with zero colour. (ie: does it glow in the dark)?

Bryce.

[emilen72]

the dust is no more present... no dust on the mainboard... no dust on the controls...
but the screen appears black... no scanline are present... and if I adjust the brightness control I have no effect on tube... still remain on the same black level...

[Bryce]

Hmmm, not good, sounds like you've got an ex-CTM. Something on the HT (High-voltage stuff) seems to be dead. Did you see any leaking from any of the large capacitors?

Bryce.

[emilen72]

seems to be two areas with some dried trace of lack(?) even the caps seems are not swollen... i will try to change all the caps around these areas... many thanks

[Bryce]

Check for burnt resistors and diodes too. I suspect it will be more than just a capacitor.

Bryce.