Commodore 64 Power Supply
Rick Stewart
I have a C64 power supply that is dead. It is supposed to be the
repairable type. There are 4 screws holding it together on the bottom,
a transformer and heat sink with the regulator and caps inside. Does
anyone know what part number to use for the regulator and is it worth
repairing? How about a schematic too?
Rick Stewart
stew...@jhuapl.edu
Michael Black
I don't really have any experience with the C64, but I did save the
following a few years ago, that might be helpful. I think I found it on a
Fidonet echo, but at this point I can't remember for certain.
There is nothing special about the C64 power supply; you can't really
build a power supply that is any simpler. If you have the kind that
doesn't have the potting compound "securing" all the ocmponents, then it
should be really easy to repair.
Michael
------------------------------------------------------------------
From: Mike Wich
To: All Msg #281, Jan 05, 97
03:39:42
Subject: c64 power supply
The orignal power supply for the c-64
is a piece if JUNK, it has blown more
computers than anything else.
Waht's wrong with it? it is POTTED and
don't dissipate heat very well the
regulator inside the power supply
overheats and blows. One of two things
will happen:
1. the regulator will open
(no 5v power at all), this usualy will
not damage the computer.
2. the regulator shorts (5v goes up to
9-12v or higher) this will cause
anything from overheating to complete
distruction of your c-64
If you have alot of lockups or glitches
for no reason at all then your power
supply may be going bad.
If you need a new power supply for
your c-64 this is the circuit for you
It's inexpensive & easy to build and
uses large capacitors for better
filtering and will help absorb some
of those SPIKES, SAGS & SURGES too.
The power requirements for the c-64
are as follows:
5v dc @ 2A and 9-12 vac @ 1-2A
the 5V supply must be well regulated
to 5V +- .25 V
PARTS:
T1 120 to 9V @ 3A transformer with 2
9V secondarys. if you can't get a
transformer with 2 secondarys then
use 2 9V transformers one for dc and
one for ac
BR1 bridge rectifier 100 volt @ 5Amp.
or higher
ic LM323-K or T or eqiv. voltage
regulator
c1 1000 mfd 35 volt capacitor
c2 100 mfd 25 or 35 volt capacitor
--------------------------------------
schematic diagram
--------------------------------------
t1
120v
*--- 9VAC
--* *---
T1 * continued at
--* *-++-----O------a a below
*-++--- I
BR1 I =C1
I I
G G
LM323-K or LM323-T
I------I 5v
a--------Ol ic lO----O------- + 5v
i I------I o I --- -
r1 Ig = c2 I
G I I
G G
the connector on the c-64:
6 7
9Vac---.U.---9Vac
. .
. .
Ii
2/ I5
I I
- +
5Vdc
--------------------------------------
NOTES:
If you use a LM323-T or LM323-K
5v@3a regulator this will power
a fully loaded c-64.
USE ADEQUATE HEAT SINK ON REGULATOR IT
WILL GET HOT!!!
FOR MORE PROTECTION INSTALL A MOV
ACROSS THE 120 V LINE AT THE
TRANSFORMER. Radio Shack # 276-568
FOR EVEN MORE PROTECTION: Install a
crowbar circuit from the 5v supply to
ground
------------------------------------
G circuit ground
= capacitor
------
---I I--- voltage regulator
in ------ out
I
G
*----
--* *---- 9v
* transformer
--* *----
*---- 9v
++ bridge rectifier
++
use adaquate heat sink on the regulator
it will get HOT!!!
-------------------------------------
I hope this helps. Commodore uses
some wierd numbering on there
connectors I know this works. I
built my own power supply when the
original power supply failed. It's
been going good for over 2 years now
and no more GLITCHES.
end..
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* Origin: Classic Image BBS--Las Vegas (1:209/308)