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makore
Account closed
Registered: Feb 2008
Posts: 6 |
lack of 9v from the c64 psu
hi everybody
recently i checked if the c64 power supply is ok,
i connecter a multimeter and checked all the pins
in the power chord connection.
i've noticed that there is no 9v source from the psu,
there is only the 5v (5.3 actually).
my question is :
what is the purpose of the 9v source ?
is that normal that it does not function?
is there something to do if i have the brick type psu?
thanks ! |
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WVL
Registered: Mar 2002
Posts: 896 |
Did you check for AC voltages on your multimeter?
The 9V is AC, not DC like the 5V. Anyway, the c64 uses it to make 12V for the SID. |
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TNT
Account closed
Registered: Oct 2004
Posts: 189 |
It's not only for SID. C64 uses AC frequency for CIA TOD clocks, and in addition to powering datasette motor 9 VAC is also routed to user port. |
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makore
Account closed
Registered: Feb 2008
Posts: 6 |
that's embarrassing! i checked only the DC voltage...
thanks for that remark WVL.
anyway i guess that if i have sound so everything is
just fine with the 9v Ac...
do you guys think that the 5.3v (i guess it raises when the computer is loaded) can be bad for the electronic parts?
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Mace
Registered: May 2002
Posts: 1799 |
Don't think I'm a hardware guru... but couldn't it be that the 5.3V drops a little under load?
And that's a question, not a suggestion... really :-)
You were measuring the 5.3V without any load but your multimeter... |
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MagerValp
Registered: Dec 2001
Posts: 1074 |
To properly measure C64 voltages, connect the PSU to the C64, turn it on, and measure on the user port when the computer is running.
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enthusi
Registered: May 2004
Posts: 677 |
and yes, when 9 AC fails you may not notice when you are one of the floppy drive lamers :)
Well check here:
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64.. |
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TNT
Account closed
Registered: Oct 2004
Posts: 189 |
Quote: To properly measure C64 voltages, connect the PSU to the C64, turn it on, and measure on the user port when the computer is running.
Remember that if you are unsure about the PSU voltages then it might be better to use something else than C64 as test load. |
