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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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1st Jul 2019, 2:34 pm | #21 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,549
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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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1st Jul 2019, 10:31 pm | #22 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
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Re: Philips CM11342/55G video monitor
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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3rd Jul 2019, 1:37 pm | #23 |
Tetrode
Join Date: May 2007
Location: Downham Market, Norfolk, UK.
Posts: 83
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Re: Philips CM11342/55G video monitor
Has anyone got a diagram for this monitor
Dave..
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3rd Jul 2019, 2:07 pm | #24 |
Dekatron
Join Date: Apr 2012
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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. |
3rd Jul 2019, 5:31 pm | #25 |
Tetrode
Join Date: May 2007
Location: Downham Market, Norfolk, UK.
Posts: 83
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Re: Philips CM11342/55G video monitor
This one ?
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3rd Jul 2019, 6:48 pm | #26 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
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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. |
3rd Jul 2019, 7:24 pm | #27 |
Tetrode
Join Date: May 2007
Location: Downham Market, Norfolk, UK.
Posts: 83
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Re: Philips CM11342/55G video monitor
Hi ok I have it now, but there’s 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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4th Jul 2019, 12:13 am | #28 |
Dekatron
Join Date: Dec 2007
Location: Haarlem, Netherlands
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Re: Philips CM11342/55G video monitor
Indeed. Or disconnect R3520 which may be easier.
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5th Jul 2019, 1:06 am | #29 |
Dekatron
Join Date: Apr 2012
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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. |
12th Jul 2019, 7:49 pm | #30 |
Tetrode
Join Date: May 2007
Location: Downham Market, Norfolk, UK.
Posts: 83
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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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13th Jul 2019, 12:57 am | #31 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
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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. |