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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 1st Jul 2019, 2:34 pm   #21
Refugee
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Default Re: Philips CM11342/55G video monitor

Just measure the resistance from the collector of the line output transistor to earth with all in circuit. If it is not short circuit we will need to look at the rectifier diodes on the power supply.
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Old 1st Jul 2019, 10:31 pm   #22
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Default Re: Philips CM11342/55G video monitor

Quote:
Originally Posted by ljdavek View Post
So Iím looking at the pin out of the LOPT thatís on this post would it be pin 10 I disconnected and connect the light bulb to instead? For testing the power supply?
I am a bit of a novice at repairing CRTs sorry..

Dave.
That would be the supply rail going to pin 3. There's a small chance you'd damage the H-center circuit if you disconnect the supply directly at pin 3 as opposed to somewhere nearer to the power supply. I don't know if that's appliccable here and haven't found a schematic yet to look it up.
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Old 3rd Jul 2019, 1:37 pm   #23
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Red face Re: Philips CM11342/55G video monitor

Has anyone got a diagram for this monitor

Dave..
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Old 3rd Jul 2019, 2:07 pm   #24
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Default Re: Philips CM11342/55G video monitor

Most computer monitors have very scant servicing information.
With a hard short like you have got I would start with the heater diode.
On the first photo in post#9 it is the closest to the opto coupler that can be seen bridging over the thick white isolation line between the mains and isolated parts of the board.
Just unplug the tube base and measure it in circuit. Most CRT displays regulate the heater voltage and allow the rest of the outputs follow.
Use a UF5406 or UF5407 type diode and not the IN variety. That little grey one looks like it was working quite close to its maximum rating.
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Old 3rd Jul 2019, 5:31 pm   #25
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Default Re: Philips CM11342/55G video monitor

This one ?
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Old 3rd Jul 2019, 6:48 pm   #26
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Default Re: Philips CM11342/55G video monitor

Philips monitors were always very well documented. I think the CM11342 is also known as the CM8833 MK2 or CM8833-II.

Tanya seems to have it: https://elektrotanya.com/philips_cm1.../download.html though that one is for the /05 version. Some slight differences may occur.

Last edited by Maarten; 3rd Jul 2019 at 7:08 pm.
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Old 3rd Jul 2019, 7:24 pm   #27
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Red face Re: Philips CM11342/55G video monitor

Hi ok I have it now, but thereís loads to look at !! So the safest way to isolate the LOPT would be disconnect pin 3 not pin 5 .....
Dave...
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Old 4th Jul 2019, 12:13 am   #28
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Default Re: Philips CM11342/55G video monitor

Indeed. Or disconnect R3520 which may be easier.
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Old 5th Jul 2019, 1:06 am   #29
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Default Re: Philips CM11342/55G video monitor

The blue circle is around the mains rectifier.
Above that is the 6 pin opto coupler and a capacitor. Test the grey diodes above that capacitor.
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Old 12th Jul 2019, 7:49 pm   #30
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Default Re: Philips CM11342/55G video monitor

Ok I disconnected the resistor then powered it up and got 120odd volts at the resistor... i think I got the right diode and checked that it was ok it was a round Gray one ... il try show you in a photo what I checked ....

Dave ..
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Old 13th Jul 2019, 12:57 am   #31
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Default Re: Philips CM11342/55G video monitor

Those are in the right area.
Carry on checking the grey diodes and you will find one that is short circuit.
When you find it you can use UF5405 or UF5406.
Do not be tempted to use 1N54XX as they will overheat.
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