PET 2001 16 N Mystery - test-drb@ccmp.vtda.org

31 Jul 2003

...
 From: ard(a)p850ug1.demon.co.uk

  I wish to pose this question with the hope that
there is someone 
 else who has had the same thing happen to them, and/or can suggest 
 a cause/fix..

 I have a Commodore PET 2001 16 N.  Whenever I try to write or read 
 from tape (using 1530 drive) the computer freezes up and I am forced 
 to turn off/on.  After powering the unit back on, the screen is filled  
This sounds like a power supply problem -- the extra load of the tape 
drive motor is pulling the unregulated supply down, which is then 
causeing the 5V line to drop too low.

Many PETs have a white Molex 0.156" power connector on the mainboard, the 
socket part of which is wired to the transformer and smoothing capacitors 
mounted seprately in the case. This connector is somewhat under-rated, 
and tends to go high resistance and overheat. If the plastic has started 
to turn brown, this is one of your problems. 
Hi
 Put DC#4 on the pins and don't worry about it.
Dwight

...

Either replace the connector, or remove it completely and solder the 
wires directly to the main PCB (you might then want to add an in-line 
connector of a suitable rating to aid future servicing).

Also, check the smoothing capacitors (particularly the large ones mounted 
off the main PCB). It's possible one of those has dried up.

-tony 