Osborne 1 (OCC 1) basic troubleshooting? Can't boot

[JNZ]

I have an Osborne OCC 1 I'm trying to repair, and I observe the following behavior:

1. Machine beeps on power-on and I see some introductory text on screen, including "ROM Rev 1.5/DD" and "Insert Disk into Drive A and press RETURN ...."

2. Nothing happens when I press return with disks in both drives.

I verified that the keyboard cable is plugged into the bottom of the keyboard, and the cable is attached to the machine with the output plug coming left. It's the style of plug (later style?) where it's a spiral cable in a 90 degree connector that has locking brackets.

If I press the physical soft reset button the text on the screen flickers repeatedly or disappears entirely

I opened the machine and swapped the two drives with no change in behavior. The FDD cables also seem to be connected properly to the system board (to a little riser board that connects to the main board).

(Surely unrelated, but I haven't yet replaced the two filter caps on the PSU)

Any ideas on where to start?

 

[ppcmini]

The only 1.5 Rom, I have seen is with a Neuvo DD board. At Bitsavers.org, there is a pdf in the software section of Osborne/Osborne1 on this board.

 

[GeoffB17]

Can you hear the disks spinning? Is there any sound of disk access?

Have you cleaned the disk drives. Error message compatible with no disk present, this could be because sensor is dusted up, so disk present is not detected. A good blow in each side of the drive slot may help.

Less likely, have you tested the disks/checked that they are OK and contain boot data?

Geoff

 

[ef1j95]

Sounds like a problem with keyboard. Is it plugged in correctly? (Cord to left?) None of the pins are broken?

Disk A: should spin when return is pressed. Then you get "BOOT ERROR" repeating if the disk can't be read.

 

[JNZ]

Some more information:

Can you hear the disks spinning? Is there any sound of disk access?

Nope, it doesn't even try. The disk access lights don't light up and the drives don't move.

Have you cleaned the disk drives. Error message compatible with no disk present, this could be because sensor is dusted up, so disk present is not detected. A good blow in each side of the drive slot may help.

I cleaned the machine but didn't try blowing duster into the drives, I can try that, but without disks in them would the drives still spin?

I also made sure the head carriage could move in each drive, and lightly lubricated the rails. (They were different types of drives: one had a worm gear and the other looked like it slid on two rails. Perhaps someone upgraded or replaced a drive at one point?)

Sounds like a problem with keyboard. Is it plugged in correctly? (Cord to left?) None of the pins are broken?

The plug's to the left and the pins look okay, on both sides of the cable. Is there anything more I can check to see if the keyboard is working?

Disk A: should spin when return is pressed. Then you get "BOOT ERROR" repeating if the disk can't be read.

Will it spin even without a disk in? And is Disk A: the one labelled "1" in the plastic front?

 

[ef1j95]

It will spin without a disk. Left-most. Could be unresponive key switches, in which case exercising them might help. I forget off-hand the key combo to boot the right drive, but that's something to test. I'd open the keyboard case to see what's going on there.

 

[JNZ]

It will spin without a disk. Left-most. Could be unresponive key switches, in which case exercising them might help. I forget off-hand the key combo to boot the right drive, but that's something to test. I'd open the keyboard case to see what's going on there.

I opened it up but it just looks normal. The keyboard cable was connected and I didn't see any obvious corrosion or problems on the underside of the keyboard.

If it's not the keyboard what might it be? Could the CPU be in a halt state after it writes the information to the screen? And why does the reset button not reset the computer, but instead makes it flicker? (As if it's infinitely rebooting.)

 

[Druid6900]

I'm having a similar problem with an Osborne 1.

Hit Return or Enter and nothing happens or hit a bunch of keys and you get screen flicker (like it's jumping to the screen message repeatedly).

However, mine seems to be a keyboard cable problem (I believe).



As you can see, there is material missing from the cable on the right and the matching material can be seen on the strip of double-faced foam on the keyboard logic.

Now, I don't seem to be able to get any continuity on the undamaged strips on either cable, so it may still be the interface chips on the main logic.

Comments?