I found out what the toggle switch was "connected" to. And cleaning steps

[scm2000]

I have another post where I mentioned I received my Amiga 500.
Today I fully disassembled it -- while it visually looks clean, I'll be cleaning every inch of it.
I mentioned there was a toggle switch on the right side...   Here's a photo of what I found inside:


And here is where it was supposed to be connected to:



So that's a auxiliary board for the AdRAM 540 that was in the trap door.   It plugs into Gary's socket, then Gary goes in to it.   The manual for the ram board says to optionally run a wire from a jumper to a toggle switch so you can enable or disable the ram extension.

For some reason, some one cut the wire, and neatly spooled up the ends.   and it's been that way for quite a while judging by the fact dust collected on the black tape holding the wire spool at the toggle end.

Not sure why someone would do this, but it's possible the ram board isn't working, and rather than remove it and restore Gary, someone just permanently disabled it

Alternatively, someone got themselves a AdRAM extension from another Amiga (wire cut to remove it) and never finished wiring  up the toggle to it.   Also not making a lot of sense.

Now that I can see close with the photos, there is a fine layer of particles on the board...   dust or mold, or mildew... I'm waiting for some cans of PCB cleaner to arrive...

Oh, and I learned while disassembling it that the sheet metal slices fingers...

[nbache]

For some reason, some one cut the wire, and neatly spooled up the ends.   and it's been that way for quite a while judging by the fact dust collected on the black tape holding the wire spool at the toggle end.

Not sure why someone would do this, but it's possible the ram board isn't working, and rather than remove it and restore Gary, someone just permanently disabled it

Alternatively, someone got themselves a AdRAM extension from another Amiga (wire cut to remove it) and never finished wiring  up the toggle to it.   Also not making a lot of sense.

Or maybe the board is left in active state, i.e. they decided there was no reason to ever switch it off (not playng games or other that required it switched off)?

Best regards,

Niels

[scm2000]

Today I cleaned the plastic case.   I used Magic Eraser to get the grime, stains and smudges off, then cleaned with a multi-surface cleaner to hopefully sanitize it.
I found that at some point in this case's life it was held together with scotch tape at the seams.   At this point there are the torx screws (but one missing)

I see no yellowing in the case, it's a light almond color, which I think was the original color...

[scm2000]

Or maybe the board is left in active state, i.e. they decided there was no reason to ever switch it off (not playng games or other that required it switched off)?

Best regards,

Niels

I'm not sure if it's active, there should be at least a total of 1meg in there, and I see something over 300k of free memory

[nbache]

Okay, sounds like you're right. It was just a thought.

Best regards,

Niels

[scm2000]

Well the next step was to thoroughly clean everything (due to me being allergic to whatever dust or mildew was on things).
So the case got a good cleaning as I mentioned, all circuit boards except the floppy boards, got sprayed down with PCB cleaner.

I disassembled the floppy case, and took a look at the spindle, because it was giving disk failures on the power up test I did right after getting the unit.
Someone suggested to clean and re-grease the spindle.   What I found was that though I got a black smudge on the cue tip, there apparently was no sign of grease on the spindle.   It could be that it all wore away over the years, or it was very light to begin with.
I put a small amount of the grease I use for my 3D printer drive screws., a bit on each side of the slider, expecting it to get spread around by use.
I also carefully cleaned the two read/write heads with 91% isopropyl alcohol on a cue tip.

I partially re-assembled, turned it on, it started booting but I had a black screen.  I had some trouble on the first test where I had to partially insert the rca connector in the composite output to get a signal.. now nothing... I put a scope on it, and yes there definitely was a video signal there.   

My monitor accepts all kinds of inputs including composite video and separate audio.   It turned out my monitor just doesn't like the signal coming from the composite port.   So I switched to a composite to HDMI converter box and fed that to the monitor, and it worked!

I also note that the read errors went away on the floppy drive, I was able to multiple boot the floppy, previously I had a less than 50% chance of it booting.

Now that everything has been cleaned and the ram expansion re-seated, Also, the expansion ram started working... with the board in, I get 1.37 megs of ram available. Prior to that I was only seeing the .37 megs available.   However, the battery backed up RTC is not working yet.

I put a new battery in (nicely they used a standard lithium battery in the AdRAM 540), but running setclock opt save, leads to "Warning Clock at old address", and If I powercycle and say "setclock opt load" it gives the same warning and the time is wrong.
So I guess that's something to look in to.


I bought a PS/2 to Amiga mouse adaptor, nicely it also came with a PS/2 mouse... that also worked.

Next thing to test was the keyboard -- it still needs to be torn down and cleaned and have the left Amiga key repaired. but I started up CLI and just typed characters.   All keys appeared to work, except neither "enter" key worked.   It's very possible since the plunger is broken on the amiga key, and nothing to spring it to the up position, that that key is being depressed and causing trouble with the enter keys.   In any case, I need to take the keyboard apart, clean it up and put a new plunger, spring and keycap for the amiga key... so I'll take a look at the enter keys at that point.   For now, ctrl-M works for enter.

[scm2000]

The worse part of the system as far as musty smell was the block power supply.
I disassembled it and found it pretty dirty inside, maybe water damage, or just was kept in high humidity or just
in a dusty environment.
I washed it down with both PCB cleaner, and 91% isopropanol...   Well for one thing I think I am right
that this was used by a smoker, as the color of the liquid that ran off was tinted yellow.