New to me PCjr.. Weird issue surrounding disk controller

[Sharkey1331]

Hello all,
So, my new to me PCjr is now alive- as I put in a replacement switching power supply. It boots, displays RAM test, and gets through the 128k RAM test (no sidecar, no jrIDE yet).. However, then I get the two beeps, and error H. If I remove the disk controller card and reboot- I get no errors at all, after RAM test I get one beep. Seems good- HOWEVER, with no disk controller plugged in, I get no keyboard.

I should mention at this time- I have not had luck with the IR keyboard, but I'm not sure if that is due to dead batteries or not- need to try with fresh batteries. SO, this is testing only with the keyboard connector cable. If I plug in the disk controller card, I do get the error H, but will see the drive light up. Don't hear it spin much though- maybe a little tiny bit of a spin, but not much else.

Hitting enter after the Error H, it drops to ROM basic, and the keyboard works, I can type in programs, I can CTRL-ALT-INS and go to diagnostics. Sound works, display driver checks out, keyboard checks out, RAM cycles through without errors. Disk test shows broken.

Ideas? Is the disk controller card needed for keyboard read? Could a bad drive make the error H? I've unplugged the ribbon, but not the power. Also- is the jumper supposed to be on 1 (on the drive)?
Thanks!
Jason

[Chuckphd53]

Jason..
You need the Floppy controller hooked to the Drive at boot up.....
Does the Drive Spin ? if it is sticky you will need to clean.....'carefully'
also if you have spare drives laying around, remove the belt for storage

If memory serves me H error is diskette controller or Drive issue
B Error is Keyboard, accidental keypress during the boot sequence can cause errors at startup...

I've not tried booting with a plain system and the Floppy Controller board out.....

on the FLoppy controller board, you can use a pencil eraser to clean to board plug in connector, just lightly brush them until they are shinny..
no need to muscle your pencil !

as for the back side connectors, simply pushing on an off a few time will wipe the metal contacts and clean them, you can spray some
contact cleaner on the back side connectors as well as inside the mating plugs ( ie Keyboard cable) to help them as you plug on and off..
Caution, don't use any contact cleaner that is harmful to plastics, and Alcohol can cause moisture after use unless you can wipe clean
but with connectors usually you can't so I would not us it...

let us know your progress..
Chuck

[KenG]

The way I test the drive is to boot with the top of the computer off. Watch the head and see if it moves back and forth smoothly. Also look to see if the spindle is spinning freely. Usually, cleaning the drive rails using isopropanol on q-tips and then oiling using 3-in-1 or sewing machine oil on a-tips takes care of a sticky head. A drop or two of oil on the plastic spindle will loosen it up, I only had that problem on one drive though and I don’t think that causes an error with no disk in the drive. The head will cause an error.

[Sharkey1331]

Ok, thanks to all of you who replied- each of your comments solved a piece of the puzzle.

The drive "sled" (or whatever you call the head carrier) is frozen on the rails.. It's so solid, and unmoveable- I'm thinking perhaps the stepper itself is frozen.

I did have another drive- it's head carrier moves smooth as silk after clean and lube. Cleaned the heads too. I had it in stock from another PCjr long gone. It was the drive I replaced because it didn't read 100%. However, it would boot the dos disk I just created for this machine- actually it started working 100%, then gradually the more I used it, more and more "disk failure" messages. I'm gonna try to adjust the speed, as neither inner or outer marks on the calibration sticker seemed to line up with my light flicker frequency.. (It was closest to the outer marks).. At least the error H is gone! It was very cool to see this thing boot up!

Jason

[KenG]

Ok, thanks to all of you who replied- each of your comments solved a piece of the puzzle.

The drive "sled" (or whatever you call the head carrier) is frozen on the rails.. It's so solid, and unmoveable- I'm thinking perhaps the stepper itself is frozen.

I did have another drive- it's head carrier moves smooth as silk after clean and lube. Cleaned the heads too. I had it in stock from another PCjr long gone. It was the drive I replaced because it didn't read 100%. However, it would boot the dos disk I just created for this machine- actually it started working 100%, then gradually the more I used it, more and more "disk failure" messages. I'm gonna try to adjust the speed, as neither inner or outer marks on the calibration sticker seemed to line up with my light flicker frequency.. (It was closest to the outer marks).. At least the error H is gone! It was very cool to see this thing boot up!

Jason

I have had luck oiling a frozen stepper motor before, Put a drop of oil on the shaft and let it sit for a while before trying to move it manually.

[toddvernon]

I'm having similar issues as this thread with a newly acquired Pcjr. Same drive problems. The box had a bad internal power supply card that had smoked soot all over the inside. Replacing the card brought it all back to life, except the disked drive. I cleaned the heads and got the drive sled moving again with iso and lubing the rails. Head seeks, drive spins. Not sure of the drive speed, however. How do I best check that? I understand you use some kind of strobe (like old stereo turntables) but what strobe do you use and I guess from the thread you are trying to balance between the outer and inner bands?

Another "interesting" thing about this drive is its missing a chip (near the fan) that is socketed (not many chips on that drive are socketed but this one always is). Perhaps it was scavenged by a previous owner? All photos of qumetrack 142 I see has a chip in that socket. Does anyone know what that chip does? The drive does a lot of things that look normal but dies at Error H, can't read the disk, or not a system disk type messages.

Thanks!

-todd

[Chuckphd53]

The socketed chip is a termination pack...

Here is a link that may help..
https://retrocmp.de/fdd/general/resistor.htm

chuck

[toddvernon]

Thanks Chuckphd53. I just found this link this morning as well https://www.lo-tech.co.uk/downloads/man ... -drive.pdf

If I read correctly I do indeed need a termination pack as obviously PCjr is a single drive system. I bought a broken drive on eBay that has the pack so hopefully, that will be good. Probably could have gotten that pack cheaper if I had done more research ahead of time. Thanks again!