C128DCR C128 section only 12 V usage, without 12 V= problems

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C128DCR
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C128DCR C128 section only 12 V usage, without 12 V= problems

Post by C128DCR »

Hello.
I bought a C128DCR machine. The PSU faultless, the machine works.
I wanted to recognise the function of the machine, I looked at this:
http://www.zimmers.net/anonftp/pub/cbm/ ... index.html
I disconnected the +12 V= and 11 V~ voltages.
Why does not start the machine only with +5 V= voltage? Empty black screen.
On the schematics only to the 1571CR and the 8580 SID necessary +12 V= voltage.
SID CR17: http://www.zimmers.net/anonftp/pub/cbm/ ... 2-left.gif
U109 1571CR: http://www.zimmers.net/anonftp/pub/cbm/ ... -right.gif
I do not see more place where the machine uses +12 V=.
I connected the +12 V=, the machine works.
The 11 V~ uses the datassette port only, from 11 V~ to 9 V= to cassette motor 6 V=, and user port 10-11 pins.
http://www.zimmers.net/anonftp/pub/cbm/ ... 1-left.gif
Ideas?


AndrewH7
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Re: C128DCR C128 section only 12 V usage, without 12 V= prob

Post by AndrewH7 »

Sorry, only've C=64, & yes, 1 could use it + only 5 volt, but only as typewriter, as no video or tape, but could send things to printer.
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motrucker
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Re: C128DCR C128 section only 12 V usage, without 12 V= prob

Post by motrucker »

I understand what are referring to, but since I only have a C-128 these days, I have not dug into it much, with the exception of changing some of the diodes, and adding the 64Kb VDC upgrade. I found one page, that while not as technical as the Zimmers pages, still may be of interest:
http://www.bing.com/knows/search?q=comm ... &mkt=zh-cn
C-64, C-128, and Amiga A2000 user
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