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Commodore 8050 Disk drive problems.

Hello,

Great thank you for the attached file. It looks as if mine is a micro polis according to the codes on the IC's.

Yes there is a part which rotates and locks the drive system down however as I said this has to be done manually.

Thanks,
 
image.jpg

Hello,

Can anyone explain to me how the diskette latching mechanism works in a standard 8050 model. This is the model whereby you have to seat the diskette first then press firmly down until you hear a click. For anyone who needs to know the specific model it has been identified as a micropolis model.

I went through the process with a commodore repairer and we couldn't work out the difference between my drive which is unable to close and his which is able to close.

I have attached a picture of the latching mechanism inside our drives, they look identical except his is a lot cleaner that mine and functions as it should. I can upload a picture of his when it is open and when it is shut as he kindly sent me a picture however it is literally the same as mine so not sure it would be of any use.

Thanks,
 
I'm not sure I'm familiar with that one but I'd expect it's a simple cam. If theres a plastic cam glued to a metal spindle that has come loose, that would do it.

I can't recall ever seeing a 5.25 or 8 inch drive that didn't require the user to manually close the latch. So I doubt there's anything electronic about it.
 
By the way,I don't think there's enough to see in that picture to help. It would help if you had multiple angles, and a picture of the front face of the drive.
 
Hello,

It is really difficult to get multiple angles as you only have a small area available, but I have uploaded a front view and a view of his when it is open and closed.

Could you describe to me how this cam works? From what I understand there is that black cylindrical piece of plastic when the hits the two black prongs below a smaller piece of plastic fitted to a metal rod extends out of the black piece of plastic. Now if I turn that manually that is when I can close the drive however from the picture he sent me it doesn't seem like his does that yet it still seems to close.

All I meant by 'manually' is that I have to open the top cover and twist that black piece in order to close the disk onto the spindle

Thanks,


image.jpgimage.jpgimage.jpg
 
I vaguely remember seeing drives like that in the distant past. However, I do not have any like that, so don't think I can be of much help. Hopefully someone else here is familiar with them.
 
Hello,

Okay thanks anyway for your help. If I can I plan on taking the drive out and the drive belt also needs replacing, so perhaps I can take more pictures then which will give everyone a better view of the mechanism.

Thanks,
 
Hello,

Thanks for all the help. I now have a fully working disk drive or at least think I do, but I won't know for sure until I finally test it with a PET, need to get a communications cable.

I managed to fix the latch mechanism, they didn't need any work but they were just sticky from all the years in a cupboard.

Thanks,
 
Max1227 said:
but I won't know for sure until I finally test it with a PET, need to get a communications cable.
Click to expand...

It may be difficult to find a cable. Here is a link to fabricating a PET to IEEE488 cable if needed. The Toronto PET Users Group (TPUG.ca) used to sell these cables. But I don't think they sell any hardware any more.

They still sell the TPUG Disk Library on CD:

"As announced at World of Commodore 2009, TPUG has created a CD containing the entire TPUG Disk Library!

Over 1100 disk images (D64 and ADF) containing over ten thousand programs for the C64, VIC20, Amiga, C128, and PET – many of them originals published by TPUG. Plus Historical Photos, Emulators, and the Library Catalogs in PDF format." http://www.tpug.ca/2009/12/tpug-library-cd-available/
 
I did find there is another system that uses a cable with exactly the same connectors on each end, but, with a different pinout. I bought one and had to rewire the card edge connector end.

The price of that cable was about the same as the price of the parts to build a new one, and it was just as much work.
 
Hello,

I'll definitely check that website out, thanks Dave. Regarding the cable I'm quite fortunate as I have found someone in the UK who repairs and makes these cables and I was going to buy one from him.

Thanks,
 
Don't forget the cable from the PET to the first disk drive unit is different to that from disk drive to disk drive. They have different connectors on one end.

Just want to make sure you ask for the correct cable.

Dave
 
Hello Dave,

It's the one with the edge connector at one end then the IEEE at the other isn't it?

Max
 
Hi all,

I've got good news and bad news.

The good new is the cable arrived and works well.

The bad news is my disk drive won't read/write or format.
When I use the ?ds$ command I get error 21,39 and 74 depending on how I use the drive. However it responds to all the commands but just cannot read or write to disks. I am using single sided double density disks that write on 96tpi I believe, so as close as I have to the original quad density disks.

Any suggestions would be much appreciated, I've already done the things you would normally do eg clean ports and connections and the read/write heads.

Thanks,
 
Last edited:
Max1227 said:
When I use the ?ds$ command I get error 21,39 and 74 depending on how I use the drive. However it responds to all the commands but just cannot read or write to disks.
Click to expand...

OK, it seems the IEEE488 half is working. Look at this schematic and tell us which parts are on sockets. Let's hope there is nothing wrong with the 1K ROM embedded in the 6530 RRIOT chip. The 2114 RAM chips would be candidates for swap out. These form the shared RAM between the two 6502 processors.
 
KC9UDX said:
Well I blindly replaced all the 2114s in my D9060 and it sprang to life.

I've had to replace 2114s in everything I own that uses them. Based on that, I'd recommend replacing those at this point.
Click to expand...

I've had to replace 2114s in everything I own that uses them. Based on that, I'd recommend replacing those at this point.
 
Hello,

I've been told to check motor speed for the spindle mechanism so I going to do that since when I looked at the drives drive 0 travels a lot slower than drive 1, so much so you can even hear it. I don't think they are properly calibrated. Will check the schematics out but I can already tell you that the only chips socketed are the ones at UN1, K6, UL1, UE1, UC1, UH1, UH3, UM3, UK3, basically all the bigger chips.

Thanks,
 
Yep, they never socket the SRAMs.

You can format a disk if the speed is wrong, so that's not an issue at this point.

Believe it or not, it's real easy to match the speed of the two drives assuming one is correct, by formatting in one and reading in the other.
 
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