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From: Rubywand <rubywand@swbell.net>
Newsgroups: comp.sys.apple2
Subject: Re: IIe problems. (power?)
Date: Sat, 14 Jun 1997 03:10:15 +0000
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G. Johnson or K. Hartman writes ...
>
> ....
>
> Let me rephrase my question. Some of our IIes work and some don't. I
> use the same out let to test them. We don't have power strips for IIes
> (no room in budget). Is it something internal? Does the power source
> need to be replaced? Are they unfixable and should be used for parts?
>
If "don't work" means you plug in a IIe, flip ON the power switch,
and 'nothing happens', then, there are a few quickie fix tries ...
1. Open the case and check inside for indications of Coke spills,
debris, etc.. If everything looks okay, continue on. If not clean away
the mess; it could be causing a short. After cleaning (and drying), turn
ON the power to see if the problem is fixed.
2. If there is a fuse socket, pull the fuse and check it. (If it's
blown, try replacing it. If the new fuse blows, replace it, pull all Slot
cards and try powering ON again. If the fuse does not blow, hop to #7
below. If the fuse blows with no cards installed your best course is,
probably, to forget about repairs and get a replacement power supply.)
3. Unplug and replug the power cord at the point where it connects to
the IIe. Turn ON power. Try wiggling the power cord.
4. Substitute a power cord from a known-working IIe and turn ON power.
5. Turn ON the power. Jiggle the power switch. If the machine shows
signs of life, the switch is probably bad.
6. Open the case. Unplug and re-plug the Power Supply cable to the
motherboard. Turn ON power. If the machine seems to respond, try cleaning
the power supply plug and socket.
7. Pull all cards from Slots and turn ON power. If the machine 'comes
alive' one or more of your cards may have a short or may have been
cross-socketed. Clean the contacts on each card (e.g. with alcohol). With
power OFF, replug a card (be sure to line-up card and Slot contacts) and
turn ON power. Do this for each card. If a card causes the machine to
fail, it is, probably messed up. If no card produces a failure the
original problem was, likely, a card which was not properly inserted.
If the above tries get you nowhere, remove the power supply from the
'dead' machine and swap in one removed from a good machine. (Removing
power supplies is pretty easy.) If the 'dead' machine now works you will
know that the original power supply is, probably, bad.
IIe power supplies can be repaired. The bother involved varies
considerably with the cause of malfunction. For example, 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.
Open the "bad" power supply. 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 it
is broken, 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.)
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. Continue as
outlined in #2 above.
If the power supply has a slotted adjustment, mark its current
position and, then, turn it back and forth. 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 is/was a 'dirty' voltage adjustment control.
It's a good idea to spritz the adjustment with circuit cleaner. 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 or a blown main power transistor (the big silvery
thing). Unless you enjoy electronic repair work, your best course is,
probably, to get a replacement power supply.
Naturally, no ][ hardware hacker would just dump a defective
power supply unless he/she were already neck-deep in junk parts. Whether
or not a bad power supply may have some value for replacement parts
to a school depends upon who may be available to do repairs.
Rubywand