Slightly out of topic question

[J. Larry Hendry]

These old beasts are collecting dust in many a closet in the US.  They can
usually be purchased for $25 USD.  That's less money than I had to pay for
my first replacement power supply.

----------
> From: Jay Martin <jmar at intface.com>
> To: gronda_a at starnova.it
> Cc: synth-diy at mailhost.bpa.nl
> Subject: RE: Slightly out of topic question
> Date: Tuesday, October 06, 1998 1:32 PM
> 
> Usually removing a cartridge while the unit was on would cause the power
> supply to spike.  The C64 used a 7805 type regulator that does not
contain
> protection for this.  What usually happens is the power supply suddenly
> decides to oscillate at around 8 volts.  This then fries most of the RAM
> chips (they didn't have much protection in those days).  You will
probably
> have to replace the power supply and the RAM chips.  But try just the
power
> supply first.  Believe it or not, even though the power supply is
> non-fixable (unless you got a real early one) and has a "brick" of epoxy
> covering all the components (causing the eventual demise of the regulator
> due to it's inability to dissipate the heat) they then put a FUSE in
there
> (in the middle of the epoxy).  It **COULD** just be that blew..but you
will
> most likely not be able to replace it (unless you have some solvent to
eat
> the epoxy away.)
> 
> Try the power supply and then the RAM chips.
> 
> Jay Martin
> P.S. I speak from a ton of experience, I used to work as a repair tech
for
> Commodore equipment.  
> 
> 
> 
> > -----Original Message-----
> > From:	gronda_a at starnova.it [SMTP:gronda_a at starnova.it]
> > Sent:	Monday, October 05, 1998 4:53 PM
> > To:	synth-diy at mailhost.bpa.nl
> > Subject:	Slightly out of topic question
> > 
> > Hello, I've got an old Commodore C64 (that it's also in some way an
> > analogue synth!) to repair.
> > Does anybody know what get fried pulling off a cartridge while the unit
> > is powered on?
> > 
> > Thanks.
> > Andrea