New csa2 FAQs: F002POWER (Part 2 of 2)

[Rubywand <rubywand@swbell.net>]

From: Rubywand

014- Can Apple II power supplies be repaired? What are some good
     fix tries?

     IIe power supplies can be repaired. The bother involved varies
considerably with the cause of malfunction.


Bad Power Cord

     Unplug and replug the power cord at the point where it connects to
the IIe. Turn ON power. Try wiggling the power cord. If the Power Supply
comes ON at any time, try substituting a power cord from a known-working
IIe. If this fixes the problem, you can be pretty sure that the problem
was a power cord with a broken wire.


Poor Power Supply Connector Connection

     Unplug and re-plug the Power Supply cable to the motherboard. Turn
ON power. If the machine seems to respond, or responds when the
connector is wiggled, you probably have a dirty or loose connection.

     Clean the power supply plug and socket with an alcohol swab. Using
long-nosed pliers slightly re-crimp the 'holes' on the socket (or,
insert a jeweler's screwdriver into the space between each hole and the
plastic casing and twist).  The idea is to restore a firm grip for all
contacts.

     Another possibility is a loose or broken socket solder connection
to the motherboard. The repair is to remove the motherboard and
re-solder the connections to the socket.


Bad Switch

     It is fairly easy to identify a bad switch-- it will, usually, not
snap cleanly into position, feel crunchy, and/or have a burn spot. The
repair is to replace the switch with some AC power switch that will fit.
Or, you can permanently connect the switched lines and add an in-line
switch to the power cord.


Blown Fuse

     Some power supplies may have a fuse. Open the power supply. Look
for a fuse mounted to the circuit board. If there is one, check it. An
Ohm meter can be used to check for continuity if it is not obvious that
the fuse is blown. If the fuse is blown, replace it.


Bad "Globar" Element

     Look toward the end where the power cord is connected. Somewhere
close to the place where wires from the switch go to the circuit board
there should be a small disk-shaped component which is not a disk
capacitor. Probably, it will be black with no markings. This is a
"globar" resistor. Check it to be sure that it is not cracked and that
both leads are really connected to the disk.

     If the globar element is broken or if a lead has popped off, you
will need to get a replacement from an electronics supply shop. (Tell
the shop person where the globar resister comes from and describe its
size.)


Blown Electrolytic Capacitor(s)

     On the end of the circuit board near the Switch are some relatively
large electrolytic capacitors (typically these are tubular aluminum
things with shrink-wrapped grey or light-green covers on which there are
markings). Usually, they are the same size and have the same uF value
and Voltage rating. One (or more) of these may be obviously blown or may
just show some slime near the base.

     If you find something like this, the suspect capacitor should be
replaced by one of the same (or slightly larger) uF value with the same
(or larger) Voltage rating. Size and shape are, also, important in order
to get a good fit.

     When removing the bad cap, be sure to mark the "+" side on the
board-- use the markings on the cap's cover to identify the "+" side.
Install the replacement cap with its "+" lead in the marked hole.

Note: Also see the C7 fix discussion in Question 010.


Messed-up or 'Dirty' Adjustment

     The power supply may have a mini-potentiometer mounted on the
circuit board for fine-tuning voltage output. Usually, it will be
somewhere near the end opposite the Switch and will have a slotted
plastic 'knob'.

     If there is such an adjustment, mark its current position and,
then, turn it back and forth. (If you have some Radio Shack, etc.
'Circuit Cleaner', into the mini-pot first is a good idea.)

     Set the adjustment a bit to one side of the original setting and
plug in the power supply. If it now seems to work the problem was a
'dirty' voltage adjustment control.

     Check the voltage on the +5V line with a meter and adjust it to 5
Volts. (Note: _no_ output due to a dirty adjustment control seems
unlikely. Incorrect output is more probable; and, this could cause a IIe
to not work.)


     Beyond the above, you are, most likely, looking at a bombed
electrolytic capacitor which is not obviously bad or a blown main power
transistor (the big silvery thing mounted on a heatsink). Unless you
enjoy more involved electronic testing and repair work, your best course
is, probably, to get a replacement power supply.


____________________________



From: Stephen Buggie

015- What is a "Buggie Power Supply"?

     It is an external power supply, usually a surplus PC unit, which
connects to the Apple II via a heavy-duty cable.

     My IBM-style power supplies generate the same voltages (+5v, +12v,
-12v, -5v)  as those required by the Apple II.  But IBM-style power
supplies deliver 150-200 watts of power, more than twice the weak output
of the standard 60 watt Apple II power supply.  Thus, problems
associated with weak power (screen freezeups, crashes) in the Apple can
be reduced or eliminated by using an IBM power supply on the Apple.

     With a strong IBM power supply, you can fill all your interface
card slots or add extra disk drives without overloading the power
source.


     Recently, I have offered these power supplies for Apple II:


IBM 150 watt power supply, soldered to 5 ft cable; choice of either
IIgs     or IIe plug.   $27.00 plus $5.00 UPS shipping ($8.00 shipping
to Canada)

or

Cable-only; connects to IBM power supply at power-points P8, P9, and
Molex-4. Allows you to connect the IBM power supply you already own to
an Apple II (Specify whether IIgs or IIe plug is needed). $14.00 plus
$3.00 priority mail; To Canada: US$4.00.

Above cables made with heavy duty wires (AWG-18, with 600v insulation;
color-coded. All power supplies and cables thoroughly pre-tested prior
to shipping.)

200 watt power supplies occasionally available at $3.00 extra cost, but
an extra 3-4 weeks must be allowed.

Eight page illustrated instruction manual sent with each order; also the
manual is available on self-booting text-file disk.


Faster service!

     During the past month, users have had to wait 2-3 weeks from
payment to shipment.  More power supplies have arrived, and I have
ordered the cable components in larger quantities, so through the
remainder of the summer I expect to ship the orders within 4-7 days.


Steve Buggie            buggie@unm.edu
200 College Rd.         (505) 863-7504 office
Gallup NM  87301        (505) 863-2390 home