Notes on Cleaning and Repairing an Apple II Plus

[dog_cow@macgui.com (D Finnigan)]

I obtained an Apple II Plus yesterday. As is typical of me, a few hours
after I plugged it in and verified it to be working, I managed to break it.
Here are my notes from cleaning and repairing it, for future benefit. Ah,
experience. What a teacher.

What arrived was an early-model Apple II Plus, with a motherboard date of
7905 and 5-digit serial number (90k range). It had a gold power supply with
a serial number in the 100k range. Inside was a Language card, Disk II
controller, and Sup-R-Mod II. Also included was 1 Disk II drive (rainbow
cable, serial number in 100k range), goofy CH paddles with 16-pin to DB-9
adapter, some diskettes, 13-sector PROMs, and the usual manuals that one
gets with a II Plus.

When I first plugged it in and turned it on, I noticed that the color killer
circuit was a bit unstable. The text would be color-free for about 10-15
seconds, then would get fringes for awhile, then alternate back. All of the
keys on the keyboard were working except for the B key. It turned out to be
a poor electrical connection. After I pressed the key for about 20-30 times
in a row, with a bit of extra force than usual, the B started working.

I also confirmed that the Disk II drive was working, and managed to boot up
one of the disks that was included, and played the Bug Attack game using the
goofy CH paddles (so described because they did not have a knob, but rather
a 1-axis stick).

Then I decided to strip it down and take a bath (the Apple II Plus, that is,
not me).

Disassembly was fairly straight-forward. I removed the top case, power
supply, and logic board. When washing the case, I noticed that small black
pinholes appeared in the resin. I wonder if they are caused by bubbles. I
decided to not scrub so vigorously.

I board washed the logic board and pressed down on the chips. Most all of
them were loose. I did the usual technique of flinging water off the board,
then placed it on the gas heater to dry out.

Washing the keyboard was a bit more eventful. I pried off all of the keycaps
and placed them in the sink with warm water (over 100 degrees F, I'd
imagine) and soap. I managed to lose the two plastic supports which go on
either end of the space bar. They probably flew off somewhere, and I'll
spend some more time looking before I give up. This keyboard was the newer
style with flat power light and two-part encoder/switch board assembly. I
discovered that there is a switch on the encoder board which I later learned
is for controlling the Reset key behavior.

Next I put the enter keyswitch board in the sink to wash off the cigarette
tar and residue. Yes, the whole thing smelt faintly of vintage cigarette
smoke, but one had to get one's nose down into it to tell. I flung the water
off of the keyboard and placed it on the heater to dry too (I had taken the
motherboard off earlier). This is probably about when the plastic space bar
supports fell off.

The last major thing to clean was the Disk II drive. It too smelt of
cigarette smoke, even inside. I opened the case to wipe out some of the dust
on the white metal "floor" and lubricate the rods on which the head assembly
traveled. In the process, I unplugged the analog board to remove it.

Finally, I reassembled everything, and put all of the keycaps back on. The
entire cleaning took about 2 hours, I'd estimate. I waited an additional
half hour for the last bits of water to dry up. I then plugged back in all
of the cards, the disk drive, and connected the II Plus the TV. When I
turned the machine on, nothing happened. I heard the usual rapid clicking
from the power supply that is indicative of an electrical problem.

I removed the Sup-R-Mod, Language Card, and Disk II controller. When I
powered the Apple on again, it booted successfully. There was a short
circuit somewhere, I supposed. Through process of elimination (I'll skip the
details), I determined that the Disk II drive was at fault. I opened it up,
and sure enough, I had plugged the rainbow-colored data cable in upside down
on the analog board. I fixed it, and the Apple II powered on successfully,
and the Autostart ROM accessed the disk drive. It booted a disk.

However, there was another problem. The keyboard first was acting as though
I was holding down the 9 and REPT keys, though I was not. When I reconnected
the disk drive and powered up, random characters were output on the screen,
and sometimes pressing one key character would output a different character.
Some of the keys didn't work at all. Only the Reset key behaved normally.

I consulted the repair documentation that I provided online a few years ago,
and it said that the likely cause was a bad encoder. Well, I disassembled
the keyboard again, and checked all of the connections. I powered down,
waited an hour, and tried again. Still nothing, same results.

Finally, as a last ditch effort, I tried a technique which has worked for me
in the past: leave it on for a long time. At 10 PM last evening, I powered
on the Apple II Plus, and went to bed. This morning, at 10 AM, I turned on
the TV and tested the keyboard. It was working just OK! The only key that
does not work is the right shift key. It may simply need some additional
exercise, and it may not have worked when I originally received the Apple.
In any case, it's not such a big deal.

However, I am curious as to what was wrong with the keyboard yesterday. My
first thought was that perhaps there was still a little droplet of water
somewhere making a short or wrong connection.

In addition, the color killer circuit is now working properly, and I have
not had the text occasionally shift between fringe/fringeless modes. I also
learned that you cannot connect the 4 pin header of the Sup-R-Mod to the
output of a Videx 80-column card and get the TV to display 80-column video
that way. Finally, I think that the placement of the Reset key is
hilariously idiotic, and so I have left the switch in the "daredevil mode,"
and will do so until I accidentally hit Reset and get roasted. :-)

-- 
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
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