• Please review our updated Terms and Rules here

Fred the Floppy's Repair Log (8050M)

N

Nivag Swerdna

Veteran Member
Joined
Jul 17, 2020
Messages
740
Location
London, UK
Given the success over the summer with Petunia (my 2001 PET) I couldn't resist buying a very crusty not working 8050 dual floppy drive... this looks Very Challenging!

Capture.JPG

I am wondering what the first step should be... Power supply? Should I replace the 0.1uF+2x2500pF Suppression Filter thing? With what?
 
Capture.JPG

I'm starting to think about repairing the 8050 Disk Drive I bought a while back... The white paint is flaking off or more accurately it is really turning to dust and then the dust just falls everywhere. I've never restored paintwork before... how do I go about stabilising the paint so the dust stops flowing? Paint remover? Sand paper?

(I'm not sure the paintwork is original or if someone has subsequently painted it but the current paint is very unstable).

Do I need to totally disassemble the unit and sand/repaint the case separately?
 
From what I can see, the drive mechanisms are likely MPI, but the drive electronics appear to be CBM-unique. The drive chassis is probably an MPI 101--100 tpi single-sided. I know that CBM also used Tandon TM100-3M (note the "M" for Micropolis) as well as Micropolis 1015-2.

Don't know if you already knew that, but now you do! :)
 
If it were me, I'd start by giving the thing a good bath. Disassemble everything, and go over it with a toothbrush and a little bit of whitening toothpaste, make it minty fresh. Dry out parts in a clean dry location with lots of air moving over/through it.

That aught to remove any flaking paint, but it looks like there is rust on it. Unless someone has a better idea, use some very fine grit sand paper to remove the rust. You do NOT want to paint over rust. And you DO want a good layer of paint everywhere to prevent more rust.

After sanding, it might need some more cleaning, then grab some spray paint and make a mess. Well, that last part is what I would wind up doing. :p
 
Assuming the rust isn't too awful, there are rust-converting primers and might be worth a try. E.g.:

724504069201_09265826.jpg
 
SomeGuy said:
If it were me, I'd start by giving the thing a good bath. Disassemble everything, and go over it with a toothbrush and a little bit of whitening toothpaste, make it minty fresh. Dry out parts in a clean dry location with lots of air moving over/through it.
Click to expand...
I'm not sure you are being serious about the toothpaste??? I will disassemble it to just the case... will take me a while to record all the cable positions and have a go. There is rust in the vents for sure; the main surfaces are mostly white unstable paint/dust.
I'll take some more photos when I have it apart.
I've never painted anything metal before so this is a new experience for me.
Thanks for the interest.
 
Looks like you have the Micropolis drives......

Noting the cable orientations etc. I would remove the drives from the base unit, they are bolted in with 3-4 screws ... accessed from the underneath the base unit. They will slide out ... having removed the analogue board first.

Clean the analogue board with an air brush (or just a brush) and see if that is sufficient to clean it up (IPA will also work).
The digital board doesn’t look that bad so clean with a brush also and maybe some IPA.

The silver mains filter will pop at some point soon after powering up. I usually remove and rewire — only if you are comfortable doing that.

The drives themselves are more delicate obviously.... the lead screw that moves the head is greased which may have hardened. Clean the grease off and replace...
The heads will need a clean with IPA.

The case I will not comment on!

Andy


Nivag Swerdna said:
View attachment 65472

I'm starting to think about repairing the 8050 Disk Drive I bought a while back... The white paint is flaking off or more accurately it is really turning to dust and then the dust just falls everywhere. I've never restored paintwork before... how do I go about stabilising the paint so the dust stops flowing? Paint remover? Sand paper?

(I'm not sure the paintwork is original or if someone has subsequently painted it but the current paint is very unstable).

Do I need to totally disassemble the unit and sand/repaint the case separately?
Click to expand...
 
Last edited:
Interestingly it arrived with the plug having been chopped off.... I will definitely be wary testing the mains power side... expecting a bang!
 
Starting to carefully disassemble...

How do I remove the LEDs from the front panel? They are in holders of some kind?

fred_led.JPG

Push fit? Screw?
 
This is the rather clean bottom of Disk 1 (i.e. the LEFT as viewed from the front)...

fred_disk1.JPG

The fancy segmented discs (seen in the picture of the LED) are presumably calibration stickers... where would these stick? I guess they are not needed?
 
And a BEFORE picture of the lightly dusted analogue board...

fred_analog_before.JPG

There are two trimmer pots which look a bit scary to clean... fingers crossed
 
That outer locking sleeve pulls off and the led slides out from memory. If you can work with them in place that avoids accidentally splitting the ring.


Nivag Swerdna said:
Starting to carefully disassemble...

How do I remove the LEDs from the front panel? They are in holders of some kind?

View attachment 65479

Push fit? Screw?
Click to expand...
 
The segmented disc sticks on the black wheel in the photo.

Nivag Swerdna said:
This is the rather clean bottom of Disk 1 (i.e. the LEFT as viewed from the front)...

View attachment 65480

The fancy segmented discs (seen in the picture of the LED) are presumably calibration stickers... where would these stick? I guess they are not needed?
Click to expand...
 
Yup, the deal is that when the drive is spinning, you use a neon (although line-operated LED nightlight might work) lamp at 60 or 50 Hz as a strobe. Adjust the tach speed pot until the segment bars appear to stand still.

Normally, the Micropolis floppies of this period are built like battleships. Other than cleaning, lubing and adjustment, they should run forever. (I've got several of the "standard" 100 tpi ones). Back in the day they were eye-wateringly expensive; something like $600 in OEM quantites.
 
Cleaned up OK... will leave to fully dry out whilst I look elsewhere...

fred_analog_after.jpg

Need to spend time with the Power Supply... although I will probably look at the case next due to the flaking paint... not only was the plug chopped off it seems that a green Earth wire inside is also chopped... I hope they isn't something nasty going on.
 
Interestingly one of the 8050 diagnostic programs displays the drive speed and you can adjust the pot in situ .... I wonder if the calibration disc was for crude setup and the diagnostic program for fine tuning ?

Andy


Chuck(G) said:
Yup, the deal is that when the drive is spinning, you use a neon (although line-operated LED nightlight might work) lamp at 60 or 50 Hz as a strobe. Adjust the tach speed pot until the segment bars appear to stand still.

Normally, the Micropolis floppies of this period are built like battleships. Other than cleaning, lubing and adjustment, they should run forever. (I've got several of the "standard" 100 tpi ones). Back in the day they were eye-wateringly expensive; something like $600 in OEM quantites.
Click to expand...
 
You must log in or register to reply here.
Back
Top