Dug our my jr

General discussions on the PCjr

Dug our my jr

Postby jason » Tue Aug 26, 2008 4:13 pm

I dug my old PCjr out of the closet this past week. I've had it since my dad brought it home when I was about 8 and was my first exposure to computers. Good times with that computer :).

Here's what I've got:
PCjr
IR keyboard
32 kB expansion module
PC Enterprises 1.2MB parallel port (I believe) expansion via sidecar
512 kB expansion module sidecar
Parallel port sidecar
original color monitor

I played around a bit and failed to get it to boot, so I stripped it down to bare bones (32 kB and no sidecars). It tries to boot, I get the IBM logo screen (I was SO happy to see that again, hehe), but it won't boot off any of my disks that should all be self loading.
My old DOS disk gives me a boot failure message
Some of my other disks seem to get stuck in a loop of resetting over and over again.

I've checked the power supply and the +5 and +12 outputs seem to be good (I have not tested them under load however)
The transformer is putting out around 17 volts AC, which seems right.

I have tried putting in two other floppy drives I had laying around (1.2MB, one of them being the PC enterprises drive, both are TEACs), but the original drive in the system does best, the other two 1.2MB drives move a little and the system goes straight to basic.

Other symptoms are my IR doesn't work on my keyboard and I can't find the keyboard cable.

I have alsy tried reseating the power supply and floppy controller boards.

Any ideas?

I've already ordered a ton of parts off of e-bay to attempt to isolate the problem :mrgreen: . I'm suspecting the floppy controller, but I'm not sure.

Anyway, hi to everyone! Glad to see some others who have try to keep these systems!!
Jason
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Re: Dug our my jr

Postby Brutman » Tue Aug 26, 2008 5:11 pm

Jason,

Most of your system description I understand, except for the '32kb expansion module' and the 'PC Enterprises 1.2MB parallel port (I believe) expansion via sidecar'. Is the 32kb expansion module the memory card in the machine? If so, that's actually a 64K card. Is the PC Enterprises option an external floppy drive?

Barebones on a Jr is actually 64K, which is soldered on the motherboard.

Floppy drives are always a source of problems on an old machine. I recommend cleaning the drive first. In another thread I posted a link to a PDF file of the procedure that the Eugene Oregon PCjr club used to distribute. Basically, you clean the drive rails (what the drives head carriage slides on) with isopropyl alcohol and then you lubricate those rails with a light machine oil. I use a tube of oil with Teflon particles in it that I got from Radio Shack - it's expensive, but a little works very well. (On anything you use apply it with a Q-tip and never spray anything .. you don't want to contaminate the heads.)

The next step is to clean the drive heads. They are delicate, so this is best done with a dedicated 5.25" cleaning diskette. If you do not have one available it can be done with Q-Tips and isopropyl alcohol, but you need to be extremely careful to not knock the heads around and out of alignment. Also, you don't want stray pieces of Q-Tip cotton being left on the heads. If you do this be very gentle.

I find that normally fixes drive problems. The other thing that might be wrong is that the drive belt on the bottom of the drive might be stretched or worn and causing the drive to spin the media at the wrong speed. There is some tolerance built into the drives/media for drive speed RPM differences, but if it goes too far the diskette drive won't be able to read or write diskettes not created on that drive.

After you clean the drive get a blank diskette and run the built-in diagnostics. That should give you a good idea on if the drive is usable or something deeper is wrong.

Problems with the floppy controller are very rare - there are no moving parts to fail. Don't bother with the 1.2MB drives - the distance between tracks is 1/2 what it is on a 360K drive because 360K drives have 40 tracks and 1.2MB drives have 80 tracks. The first track will be readable, but nothing else. You will actually have better luck with a 1.44MB floppy drive, as those are always 80 tracks whether they are 720K or 1.44MB drives.

On the keyboard problems ...

You do have batteries in the keyboard, right? :-) Nice fresh alkaline batteries installed correctly, or nothing works. If that is not the problem it is possible that the lighting in the room is too bright, or that the IR sensor has been shaken loose on the motherboard. It is a separate module - just press down slightly to ensure that it is seated and that the receiver is aligned with the hole in the case.

In general be careful when handling the cards and pieces. The pins are easy to bend, and that is a pain to fix. Proper static protection should be used too. Dig out the 'Guide To Operations' and run the diagnostic procedures .. test every possible option to isolate what is wrong.

These things are hard to 'wake up' after an extended slumber. Don't let it sleep that wrong again. ;-0
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Re: Dug our my jr

Postby jason » Tue Aug 26, 2008 5:48 pm

Brutman wrote:Most of your system description I understand, except for the '32kb expansion module' and the 'PC Enterprises 1.2MB parallel port (I believe) expansion via sidecar'. Is the 32kb expansion module the memory card in the machine? If so, that's actually a 64K card. Is the PC Enterprises option an external floppy drive?


Sorry, you are correct, I was referring to the 64k that goes on the ISA looking slot in the system itself.

Yes, the PC Enterprises drive is an external floppy drive (mounts on top of the original case)

Brutman wrote:Floppy drives are always a source of problems on an old machine. I recommend cleaning the drive first. In another thread I posted a link to a PDF file of the procedure that the Eugene Oregon PCjr club used to distribute. Basically, you clean the drive rails (what the drives head carriage slides on) with isopropyl alcohol and then you lubricate those rails with a light machine oil. I use a tube of oil with Teflon particles in it that I got from Radio Shack - it's expensive, but a little works very well. (On anything you use apply it with a Q-tip and never spray anything .. you don't want to contaminate the heads.)

The next step is to clean the drive heads. They are delicate, so this is best done with a dedicated 5.25" cleaning diskette. If you do not have one available it can be done with Q-Tips and isopropyl alcohol, but you need to be extremely careful to not knock the heads around and out of alignment. Also, you don't want stray pieces of Q-Tip cotton being left on the heads. If you do this be very gentle.


I already found and printed that document, I saw where it describes the rail cleaning, but not the head cleaning. I HAD a head cleaning diskette somewhere, I'm about to go look for it.

Brutman wrote:After you clean the drive get a blank diskette and run the built-in diagnostics. That should give you a good idea on if the drive is usable or something deeper is wrong.


This is the ctrl-alt-ins thing? I don't have a working keyboard yet, so I'm stuck there at the moment :lol:

Brutman wrote:You do have batteries in the keyboard, right? :-) Nice fresh alkaline batteries installed correctly, or nothing works. If that is not the problem it is possible that the lighting in the room is too bright, or that the IR sensor has been shaken loose on the motherboard. It is a separate module - just press down slightly to ensure that it is seated and that the receiver is aligned with the hole in the case.


Yep, new batteries, I also tried reseating the IR module, no joy. What's odd is if I just start pressing keys a lot while it is POSTing, it will give me an error. So it's almost like it recognizes it..but not quite.

Brutman wrote:These things are hard to 'wake up' after an extended slumber. Don't let it sleep that wrong again. ;-0


Will old floppy disks still work after being reformatted, or is it once they are dead/unreadable there is no recovery? I'm not sure exactly how floppies degrade. :?:

Time to go hunt down my cleaning disk!
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Re: Dug our my jr

Postby Brutman » Tue Aug 26, 2008 8:15 pm

My apologies. Telling somebody to run the diagnostics when they can't get the keyboard to function is kind of faux pas ... I try not to brain fart like that too often.

The 'machine cleaning' document doesn't discuss cleaning the drive heads by hand because it is a delicate procedure and the audience for that document was fairly non-technical. I'm thinking of doing a head cleaning 'how to', but I'm really concerned about encouraging people to go reach in with Q-Tips and mess around with the heads .. it's just too easy to damage them. So if you don't find the cleaning diskette write back and we'll talk some more.

Diskettes are prone to aging too. I've had good luck with my older Maxell, Kodak and IBM branded diskettes. I've heard some horror stories about Wabash. If you look at the diskette and it looks like it has uneven wear in the exposed part, then either a damaged drive head carved it up or the binder that holds the rust on is giving up and the diskettte is turning to dust. Don't put one of those in the drive, as that's just going to force a head cleaning.

It sounds like you need a keyboard cord or another keyboard to test with. If you can't locate yours we can talk offline about how to get another one.
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Re: Dug our my jr

Postby jason » Sat Aug 30, 2008 11:21 am

SUCCESS!!!

I got my 5 1/4" IBM drive I ordered off of ebay and ran upstairs and plugged it in. This one WORKS! So my old drive has some sort of issue, I'll put it aside for now and attempt to clean it or something more thoroughly (rails, etc.). Now if I just had a keyboard I could use, I'm stuck staring at the Enter new date: prompt! lol.

:lol:
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Re: Dug our my jr

Postby jason » Sat Aug 30, 2008 1:54 pm

Image
Image
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Re: Dug our my jr

Postby Brutman » Sat Aug 30, 2008 4:01 pm

So, what's the plan for the keyboard? Are you ebaying for a new one?
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Re: Dug our my jr

Postby jason » Sat Aug 30, 2008 9:44 pm

Brutman wrote:So, what's the plan for the keyboard? Are you ebaying for a new one?


Yeah, one is coming, as well as a connector cable since I can't find mine at the moment, so one way or the other I should be good again.
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Re: Dug our my jr

Postby jason » Mon Sep 01, 2008 3:04 pm

Woot, got it working!

Oddly enough, apparently it didn't like one of my AA batteries...The ones I had put in it were new, but I tried 4 other new ones anyway all viola... :? . Oh well, can't complain :).
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Re: Dug our my jr

Postby jason » Tue Sep 02, 2008 7:18 pm

*sigh*

Okay, my machine is back to not working again. :(

I was in the process of putting in the new floppy drive permanently into the system (instead of sitting on top of the system for testing). And yes I had an anti-static wrist strap on. I also put on the PC Enterprises 512kB memory sidecar and PC Enterprises parallel port expansion for my HD 5 1/4" drive and was hoping to get started on getting all of that working again. Well, I boot it up and the drive runs for like 2 seconds and the system goes straight to BASIC, doesn't even attempt to boot the disk.

So after a few minutes, I take the system back apart again and back to just 128 kB and the 5 1/4" drive. Still no joy, same response. I take the drive out of the system, reseat the floppy and floppy controller..no change. I put the old drive back in the system, and it behaves just like it did before, won't boot anything, but at least it tries.

I ran the system diagnostics on the floppy drive, I get a code B on the old drive "Have your PCjr serviced", and a code C on the newer (to me at least) drive "diskette is write protected"...which it's not.

Anyone have any ideas?

PS
Oh yeah, on one of the drives, it almost sounded like the motor was speeding up and slowing down a little bit (the drive motor, not the motor for the head).
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