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Unique S-100 computer (Z-80/Vector Graphic/Micropolis)

nullvalue

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How about one of the ten unused 2708 sockets on your PROM/RAM board ;)

Mike

Sorry, not sure I understand? Wouldn't I have to type a command to read the EPROM? How could I do that if the keyboard EPROM is in the PROM/RAM board? Remember, I don't have any other S100 computers..
 

nullvalue

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Has anyone seen a case like this before? I know it seems silly but I can't for the life of me figure out how to get at the keyboard.. I want to pull the keyboard PCB out to do some repairs but I can't open the keyboard section of the case.. it doesn't open from the bottom..
 
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nullvalue

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Here are some pictures of the inside & one of the bottom - if anyone can figure out how to open the keyboard compartment?
 

MikeS

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Yes that was the first thing I tried - they do unscrew and remove however, they aren't connected to any kind of stand or anything inside - so removing them didn't help.

Odd; does it look like the edges wrap around, i.e. is that cover with the narrow slot part of the bottom? If not, maybe a little gentle prying in case something's 'gluing' it on?
 

JonB

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Picture 3 is a bit of a clue - the hook in the slot. Look for a fastener on the sides that would prevent sideways movement of the keyboard (and hence releases the hook). I'm going to suggest those bolts either side of the ribbon cable.

The bottom panel really looks as if it is sort of L shaped, wrapped around the rear face of the keyboard and hooked under the front edge, so if you manage to release the keyboard you'll probably find screws behind it to remove the panel.
 

tingo

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I agree - it looks like the locks on either side of the ribbon cable are "slide" locks, try sliding them upwards and see if something loosens. Then figure out if that connector needs to be disconnected as well. Finally try to move the keyboard sideways.
 

nullvalue

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I agree - it looks like the locks on either side of the ribbon cable are "slide" locks, try sliding them upwards and see if something loosens. Then figure out if that connector needs to be disconnected as well. Finally try to move the keyboard sideways.

Thats what I thought too - I tried to move them and they wouldn't budge. Afraid of damaging something, I stopped. I tried again with a screwdriver and and had to really had to pry hard on those suckers but was able to get them to unlock. Then the keyboard easily separated from the rest of the case.. No need to remove the ribbon cable - connects with a DB25. Thanks guys!
 

nullvalue

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20200315_173528.jpg

So these are Key Tronic magnetic reed switches. I have about 10 keys that aren't working.. Tried a continuity test, I am not getting a signal. Is it common to have to replace the reed switches? I thought I read these types of switches are supposed to be extremely durable. I can't see anything physically wrong with them. I tried a different housing on the non-working keys, no difference. Is there anything else I can test? Is there a place I can order replacements? Or should I just swap with lesser-used keys?
 

nullvalue

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I can't find any replacement switches online, so what I did was pull the switches from the numeric keypad to replace the broken keys on the main area of the keyboard. I have a 2nd set of numbers across the top, so it'll get me functional for now.
 

nullvalue

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20200312_152435.jpg 20200312_152449.jpg 20200312_152648.jpg 20200312_192622.jpg 20200313_202120.jpg 20200315_110633.jpg 20200315_120815.jpg

Worked on cleaning/restoring the Micropolis dual 5.25" drive this weekend. Opened it up and found a nice little surprise... an old wasp nest! Cleaned up easily though. Took everything apart, greased the moving parts but overall it seemed in pretty good condition. Tested the power supply separately, was putting out a clean 24v at the main cap. Just have to replace the power switch which for some reason is seized up and won't budge. Belts seem loose but are functional. Also had to fix a section of the power cable.. no big deal. Plugged it all in and at least I'm getting "1"s on the LED displays. The top drive whirs up for moment, then stops. It's not hooked up to anything just yet...

One question I do have though... When I put a disk in, there are two steps.. push the disk in all the way until it 'locks' back, then push down to engage the head. However, when I push down it does not lock in place. It just pops back up.. Both drives are doing this. When I push down, the drive does spin up for a moment, then stops. Not really concerned with that yet though, right now I'm just wondering why it doesn't stay shut/down?
 

deramp5113

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The door latch mechanism has to be fixed every time I refurb a Micropolis Drive. The door is much more complex and problematic than the simple manual door that most manufacturers used.

Clean up as much of the old grease in the catch and release mechanism as possible, then regrease.

Mike
 

nullvalue

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As you slide in a disk, it properly engages the latch and the disk stays in. Just when you push downwards, it does not stay down. It almost looks as if there's a solenoid of some sort that's supposed to engage? or is there really just another latch mechanism? Thanks again
 

exidyboy

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In order to hold the door closed the latch mechanism is spun a quarter turn by a spring mechanism after it has passed through the "forks" that stick out at right angles from the drive bezel. If it can't spin freely into the locked position the door will just open again.
 

nullvalue

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In order to hold the door closed the latch mechanism is spun a quarter turn by a spring mechanism after it has passed through the "forks" that stick out at right angles from the drive bezel. If it can't spin freely into the locked position the door will just open again.

Thanks guys, I see what you're talking about. Got it to latch by spinning manually. Going to clean it up & see if that does it.
 
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