Subject: Re: IIe problems. (power?)
From: Rubywand <[email-masked]>
Date: Sat, 14 Jun 1997 03:10:15 +0000
Newsgroups: comp.sys.apple2

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