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Osborne Executive floppy drives keeps spinning

C

chaolizi

Member
Joined
Mar 17, 2023
Messages
11
Hi, I'm new to the group, so correct me if I do something wrong :)

Long story short, I got an excellent condition Osborne Executive, the only issue is, it has errors. The machine will power fine, but:

1. when power on, both floppy drive goes on and keeps on and spinning. (LED keeps lit)
2. On the monitor, it displays "Computer not working properly, please contact an Osborne dealer....." (attached pic)
3. after pressing reset, it will go to a funny boot screen, with the normal rom information, but whole bunch of 0s filling up half of the screen
4. it will ask for a disk, but the floppy drive stays on all the time, so naturally I don't want to put anything in it. (It responses to keyboard when I hip enter)
5. I have the impression that these units should beep, but this one doesn't make any sound.

I have done the following to see if anything would change:

1. removed the mainboard, ram board, floppy drives to clean them (no help)
2. re-seated all chips and cleaned their pins (no help)
3. Boot without floppy cable connected to the mainboard, but with power to floppy (same message, but floppy drives no longer spinning, which makes me believe there is something on the mainboard keeps signaling the drives )
4. connect only one floppy drive (the connected drive spins)
5. boot without floppy drive controller chip (no help and drives keep spinning)
6. remove the ram board (no display at all, but drive keeps spinning )

Right now I'm confused, I fixed a few commodores vic20s back in the day but those are way easier to figure out. Any advise will be appreciated, thanks!

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ajacocks said:
Welcome to the forum @chaolizi !

I'm sure that someone here has a good idea, but my first thought is bad RAM. Do you have a RAM tester?

- Alex
Click to expand...
Hi, Alex, thanks for the reply. I suspect the ram as well, but the problem is I don't have a ram tester. and this issue seems not very obvious which part of ram it is related to. Since the 0s are only half screen, maybe video ram? and any ram tester to recommend for this particular machine? Cheers!
 
Okay, some progress. After some playing around, it was one of the 4 2128 video ram chips, it wasn't bad, I just unplug and pug them back in many times and now it works! The system passes self-test and beeps! But the floppy drives still spins as soon as I press on the power button. So at this moment, this is the only issue left, could be a bad floppy drive controller? a short? There gotta be something keeps telling the drive motor to spin, because during the self-test, I hear the drive click and after that, just the motor spin.
 
I don't know much about the Osborne Executive. but if the screen is OK, the system is probably working with RAM OK.

I'd suspect a floppy controller chip - after all, there's not much that will switch on a drive, and both at the same time? Could be a buffer chip - Floppy drives work with open collector chips and resistor pullups. But I'd guess a floppy controller chip failure or something like that, which would cause responses likely that the Osborne wasn't expecting, and it probably has a simple error handler that kicks in for any hardware fault up to boot - eg, bad response from the FDD adapter.
 
Welcome to the forums. I know nothing about Osbornes, but you should get some excellent help here. Looks like a nice unit.
 
cj7hawk said:
Just a really dumb thought - You checked that the FDD cable isn't reversed I assume? ( ie, upside down ).
Click to expand...
Emmm, that's a good point, but from the shape of the cable, and the way it has hardened, it looks like to be that way for decades, but I will definitely double-check today. Btw, will there be any physical damage if the ribbon was reversed? Based on my experience with other old PCs I don't think that data cable has enough power to fry anything but just in case :)
 
tradde said:
Welcome to the forums. I know nothing about Osbornes, but you should get some excellent help here. Looks like a nice unit.
Click to expand...
Thank you! Indeed, this is a very nice unit, the internal board looks mint, screen bright and sharp, the outside after a little cleaning looks almost new (not even yellowed)! I have been looking for these models for a long time and really want this one to work as original, otherwise, I will gut it and build a modern working station inside (It will be cool, but IMO not the best ending for a somewhat rare unit :))
 
cj7hawk said:
I don't know much about the Osborne Executive. but if the screen is OK, the system is probably working with RAM OK.

I'd suspect a floppy controller chip - after all, there's not much that will switch on a drive, and both at the same time? Could be a buffer chip - Floppy drives work with open collector chips and resistor pullups. But I'd guess a floppy controller chip failure or something like that, which would cause responses likely that the Osborne wasn't expecting, and it probably has a simple error handler that kicks in for any hardware fault up to boot - eg, bad response from the FDD adapter.
Click to expand...

Thanks for the advice!

Ya, after re-clean all the sockets and reseat all chips again, I'm pretty sure something on the board is acting up and I also highly suspect the FDD control chip now, I saw there are some ram for the FDD, but I feel those have nothing to do with turning drives on/off or sending commands.

I did some extra test last night, the FDD will click (like its looking for a disk, but only half-second) at powder up (immediately when I press the power button), then it just spins. The system on will perform self test and beeps when it's complete and passed. It will then ask for the disk and hit enter. I hit enter, nothing happens, the drive just keeps spinning, LED solid red and no click sound, then the system will put a boot error message on screen.

I never played much with 5.25 drives, on my commodores, I went straight for the emulator. But I feel no matter who's the manufacturer, the drive should make some click sound when I hit enter right? The head should be looking for the right track on the disk just like the 3.5 FDDs, or the 5.25 FDDs have different working logic?
 
In the Osborne 1, it would probably damage the power supply and kill the computer since the cable carries power. However in the exec they look like normal drives, so I'm imagining that they will not.

Also, the normal floppy cable is resistor pull-up and open collector on every pin, so it's possible you might damage a badly built read pin if it was pushing high, but I doubt it would cause any permanent damage due to the interface design.

Also, I'm working off the idea that it might have been put in wrong 40 years ago, and left that way, because it wasn't working and whoever reassembled it didn't have the skills to realize it was the wrong way around and just assumed it was broken and left it - and it would have the result of selecting the drive, which would turn the lights on and drive the motor without stopping.

So just check with a multimeter - if all the data pins are shorted together, or several are, it might be a reversed cable.

Finding Pin1 on old floppies can be a challenge :)
 
cj7hawk said:
In the Osborne 1, it would probably damage the power supply and kill the computer since the cable carries power. However in the exec they look like normal drives, so I'm imagining that they will not.

Also, the normal floppy cable is resistor pull-up and open collector on every pin, so it's possible you might damage a badly built read pin if it was pushing high, but I doubt it would cause any permanent damage due to the interface design.

Also, I'm working off the idea that it might have been put in wrong 40 years ago, and left that way, because it wasn't working and whoever reassembled it didn't have the skills to realize it was the wrong way around and just assumed it was broken and left it - and it would have the result of selecting the drive, which would turn the lights on and drive the motor without stopping.

So just check with a multimeter - if all the data pins are shorted together, or several are, it might be a reversed cable.

Finding Pin1 on old floppies can be a challenge :)
Click to expand...

Ya, it looks like a regular 5.25FDD with the big 4 pin power supply.

The unit has definitely been took apart, seller said it works 20 years ago, but I will check with a multimeter regardless haha.

BTW, should I check on the FDD end or the board end though? If the drives are good, I unplug it from the board, there should be nothing, and I plug in (If reversed), both on the board end and the FDD end I should see short at data pins right?

Also on this model, the floppy cable extends and has an external connecter where the main power cable is plugged in (so it's one cable, 3 connectors), that makes me bit confused about how the cable is configurated and I never seen such configuration before which makes me think the cable is a replacement. I will grab a pic when I got home.
 
Well, the assumption is that on the Osborne end, at least, all grounds are connected, and if reversed, then the cable would be connecting all the data pins, and would pull them all down, hence activating every single signal include floppy select ( on both drives ) and Motor enable, Write, Step, Dir, etc.

So you could measure on either end... But as the floppy polarity isn't marked on my Osbornes, it's possible it's not marked on the Executive either.

Back in the day, they used to set floppy drive ID with jumpers, or in the case of the O1, with a resistor network. In the PC, they sometimes did it that way, but to simplify assembly and deal with a constantly changing line of floppy drives, which often weren't well documented, they settled on using Floppy ID 1 for ALL drives, and using a twist in the cable to swap Select 0 and Select 1. Hence PC cables have a twist.

You can probably use a PC cable with the executive also, but would need to be mindful to set both drives to ID 1.

You also might be able to go looking for the polarising marks on the FDDs and the Main Board as an alternative, and make sure the red wire aligns with both.
 
cj7hawk said:
Well, the assumption is that on the Osborne end, at least, all grounds are connected, and if reversed, then the cable would be connecting all the data pins, and would pull them all down, hence activating every single signal include floppy select ( on both drives ) and Motor enable, Write, Step, Dir, etc.

So you could measure on either end... But as the floppy polarity isn't marked on my Osbornes, it's possible it's not marked on the Executive either.

Back in the day, they used to set floppy drive ID with jumpers, or in the case of the O1, with a resistor network. In the PC, they sometimes did it that way, but to simplify assembly and deal with a constantly changing line of floppy drives, which often weren't well documented, they settled on using Floppy ID 1 for ALL drives, and using a twist in the cable to swap Select 0 and Select 1. Hence PC cables have a twist.

You can probably use a PC cable with the executive also, but would need to be mindful to set both drives to ID 1.

You also might be able to go looking for the polarising marks on the FDDs and the Main Board as an alternative, and make sure the red wire aligns with both.
Click to expand...
Oh buddy, I can't thank you enough!!! I did the test, and guess what, all the pins on the board were short, the cable was indeed reversed!!! I took another look at the cable and it seems to be a PC FDD extension cable with 5.25 FDD connectors on it, and that's why it has the strange female connector at the very end of the cable! And I'm pretty sure the cable came wrong because before I took it off, I marked the direction of the cable, and as I flipped the cable, I saw the real red line marking!

Once the cable is correct, all the shorts were gone and no more funny business! The FDD led flash when powered on, then goes off! System pass self test, beeps, asking for a disk in Drive A, I press enter, guess what, drive A spins and stops!

The drives I have they have correct jumpers and resistors, the system does spin up the the correct drive, thank goodness the drive connector were putted on correctly. I think you are right, at some point of time, somebody took it apart and assembled it wrong and put it in storage since then .

Now the entire machine is working flawlessly, (turns out the only thing it needs after 40 years was some chip re-seating) and all I need to do is wait for the system disk arrive then I can test the entire thing:) hopefully when I run with that reverse cable didn't ruin the drives.

One day I will re-cap it, especially the power supply, but for now with a new fan and filter, another wipe down, its a beauty humming on my table:)

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cj7hawk said:
Well, the assumption is that on the Osborne end, at least, all grounds are connected, and if reversed, then the cable would be connecting all the data pins, and would pull them all down, hence activating every single signal include floppy select ( on both drives ) and Motor enable, Write, Step, Dir, etc.

So you could measure on either end... But as the floppy polarity isn't marked on my Osbornes, it's possible it's not marked on the Executive either.

Back in the day, they used to set floppy drive ID with jumpers, or in the case of the O1, with a resistor network. In the PC, they sometimes did it that way, but to simplify assembly and deal with a constantly changing line of floppy drives, which often weren't well documented, they settled on using Floppy ID 1 for ALL drives, and using a twist in the cable to swap Select 0 and Select 1. Hence PC cables have a twist.

You can probably use a PC cable with the executive also, but would need to be mindful to set both drives to ID 1.

You also might be able to go looking for the polarising marks on the FDDs and the Main Board as an alternative, and make sure the red wire aligns with both.
Click to expand...

Oh, and here is a shot of the interesting female FDD connector coming out of the power plug panel and there is no twist on the cable which makes me think someone made this out of an FDD extension cable and decided to mount the female connector there :)

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It is indeed a thing of beauty. Having recently disassembled an Osborne and a Mac, the Osborne is by far of greater quality. The early ones were a bit rough, and 4 layer boards were coming in around the time of the Mac, and there was a different design objective, but IMO the Osborne was a better system than the Mac as design goes.

I doubt there is any damage - as I mentioned, all it would normally do is "Select" everything, and the logic signals to a floppy drive should never be driven... so it's probably all pretty safe on more modern systems. I would not like to do it with an Osborne 1 though - that would likely smoke things up.

I am as green as an early Osborne 1 screen with envy ! :) But happy for your success nonetheless.... I'm still looking for an executive one day. And if you saw my other thread, Ebay is out of the question now :( Typical postage from the US used to be around USD$125 and now it's USD$500 or so :( Not that postage has gone up -Ebay is just gouging.

I've recently started writing Osborne disks, so if you were over this way, I'd overnight you one, but it shouldn't take you too long to get one. If it's original, review the thread I recently wrote about my Osborne 1 disks shredding and damaging other disks - it is likely relevant to an Osborne Executive also, and those disk drives are unlike to be as solid as the full heights, so go easy on the heads, and consider the something-methicone if it's an original disk - or if it's a new disk that someone made recently, then just check the heads are clean before you start if possible :)

I reckon 90% chance it's going to boot on the first try :)

Regards
David
 
Nice looking system. Isn't it great when the problem is solved so easily? Enjoy it. I've never seen an Osborne to touch. :)
 
cj7hawk said:
It is indeed a thing of beauty. Having recently disassembled an Osborne and a Mac, the Osborne is by far of greater quality. The early ones were a bit rough, and 4 layer boards were coming in around the time of the Mac, and there was a different design objective, but IMO the Osborne was a better system than the Mac as design goes.

I doubt there is any damage - as I mentioned, all it would normally do is "Select" everything, and the logic signals to a floppy drive should never be driven... so it's probably all pretty safe on more modern systems. I would not like to do it with an Osborne 1 though - that would likely smoke things up.

I am as green as an early Osborne 1 screen with envy ! :) But happy for your success nonetheless.... I'm still looking for an executive one day. And if you saw my other thread, Ebay is out of the question now :( Typical postage from the US used to be around USD$125 and now it's USD$500 or so :( Not that postage has gone up -Ebay is just gouging.

I've recently started writing Osborne disks, so if you were over this way, I'd overnight you one, but it shouldn't take you too long to get one. If it's original, review the thread I recently wrote about my Osborne 1 disks shredding and damaging other disks - it is likely relevant to an Osborne Executive also, and those disk drives are unlike to be as solid as the full heights, so go easy on the heads, and consider the something-methicone if it's an original disk - or if it's a new disk that someone made recently, then just check the heads are clean before you start if possible :)

I reckon 90% chance it's going to boot on the first try :)

Regards
David
Click to expand...

Thanks! Ya, as I took apart it I was quite amazed by the quality of the chassis and boards, but to be honest, took it apart was a job, especially to get the FDDs, it was scary to lift the entire internal out of the case with every bits squeezing hahaha.

Ya, ebay nowadays is nuts, but almost every price tag nowadays can give me a heart attack (Hate to mention politics, but Canada is now in a frying pan :( ). The unit was in Canada as well so the shipping wasn't too bad (for this big heavy thing), but guess what, I have to pay 4 different kinds of taxes !!! That really hurts!

I indeed have some disks on the way, and I also sourced some blank old "new" floppies, I guess I will try to let it read one of those empty ones first just to be safe, I think your thread did popped up when I was trying to figure out the FDD issue :) Hopefully it won't be chewing my disks :)

Nonetheless, really appreciate your help! Wish you have a great day!
 
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