Author Topic: CTM644 without 5VDC and 12VDC output  (Read 506 times)

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Offline Chipmop

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CTM644 without 5VDC and 12VDC output
« on: 21:59, 18 March 21 »
Hello together,
I've searched a long time to find such a forum.
Sorry for my bad english, I give my best.
I call a "Schneider CPC 6128" with a CTM644 my own, I bought it 36 years ago ;D
Recently it stops working.
I searched of course in the forum but found no solution for my problem.
I describe as good as I can:
The screen crackles when switch on and when switch off there's a short lightning at the screen.
I measured no voltage at 12V and 5V output. I replaced a lot of passive parts but has no improvment at all. For save I changed the STK7308 to a new one, but still nothing happened. I measured at the output winding of T501(8142009) for the 12V regulator, but there's also no voltage. To besure that the 12V regulator is not shortened I removed it, but still no output at the output winding. I measure around 1MOhm at these output pins. Maybe the transformer T501 is defective? Now I'm at loss and hope somebody can help me.


Thank you in advance!
« Last Edit: 10:08, 19 March 21 by Gryzor »

Offline Animalgril987

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Re: CTM644 without 5VDC and 12VDC output
« Reply #1 on: 01:46, 19 March 21 »
Hi Chipmop.
Welcome to the forum  :D


I'm not an expert on monitors, but there are people on here, that I'm sure will be willing and able to help.


Regards,


Alan.

Offline Chipmop

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Re: CTM644 without 5VDC and 12VDC output
« Reply #2 on: 19:18, 19 March 21 »
Thanks Alan, you give me hope 8) 
It would be a pity if the device couldn't be repaired.


best regards.


Armin


Offline villain

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Re: CTM644 without 5VDC and 12VDC output
« Reply #3 on: 20:28, 19 March 21 »
Hi. Armin sounds quite german. Just wait for @Bryce joining this thread...  :)

Offline Bryce

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Re: CTM644 without 5VDC and 12VDC output
« Reply #4 on: 20:32, 19 March 21 »
I'd consider getting an external PSU and a SCART cable to use the CPC on a standard TV. The monitor might be savable, but is it worth the bother if you can continue gaming / programming on a TV you already have?

Bryce.

Offline Animalgril987

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Re: CTM644 without 5VDC and 12VDC output
« Reply #5 on: 21:04, 19 March 21 »
@villain: you called, and he appeared... :D

Offline xesrjb

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Re: CTM644 without 5VDC and 12VDC output
« Reply #6 on: 21:23, 19 March 21 »
Have a look here,




https://www.forum64.de/index.php?thread/92459-anschluss-cpc-464-an-pc-monitor-mittels-konverter/


A very good alternativ..


You can PM me in german, if you have any questions..


xesrjb
„The pellet with the poison's in the vessel with the pestle; the chalice from the palace has the brew that is true.“

Offline villain

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Re: CTM644 without 5VDC and 12VDC output
« Reply #7 on: 21:35, 19 March 21 »
@villain: you called, and he appeared... :D


That's what I expected. 😀 Wish this would work as good in other cases. 😁

Offline Chipmop

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Re: CTM644 without 5VDC and 12VDC output
« Reply #8 on: 21:53, 19 March 21 »
Such a converter could be an alternative, yes. I apprecita your suggestion, but I won‘t give up that quickly. And I like this retro monitor, it just belongs to this old computer. So I the converter will be my last emergency nail  :D
I go on searching for the issue, i suspect the problem in the area of the transformer T501 or the transformer itself.
I will keep you up to date if i have new knowlege.


@villain:with German your absolutely right ;)
[/size]
[/size]Armin

Offline Bryce

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Re: CTM644 without 5VDC and 12VDC output
« Reply #9 on: 11:10, 20 March 21 »

That's what I expected. 😀 Wish this would work as good in other cases. 😁

I just happened to be passing by :)

Bryce.

Offline Chipmop

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Re: CTM644 without 5VDC and 12VDC output
« Reply #10 on: 15:44, 21 March 21 »

Hello together again,
i fixed already one problem.The output winding of the 12V output section was actually oxidized near the connection pin. I was able to repair this, because the wire of the transformator output winding was long enough.  Now output of 12V and 5V is present and the cpc seems to start.
But the joy was not so great, because the next problem occurred right away.
It seems that the veritcal deflection is also defect somewhere.


Armin

Offline Bryce

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Re: CTM644 without 5VDC and 12VDC output
« Reply #11 on: 17:19, 21 March 21 »
It must have been stored in very bad conditions for that to happen. If that rusted through, then you're going to have many more parts that have failed or are about to fail.

Bryce.

Offline Chipmop

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Re: CTM644 without 5VDC and 12VDC output
« Reply #12 on: 21:22, 21 March 21 »

Quote
It must have been stored in very bad conditions for that to happen. If that rusted through, then you're going to have many more parts that have failed or are about to fail.
That's really not the case. It was stored always in dry area.


But in the meantime my CPC is back. The vertical deflection problem was my fault. I accidentally switched SW401 to GND :doh:
Only the colors should be better adjusted.


Thanks for your comments


Armin