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Retro Canada
November 28th, 2017, 08:26 PM
On my 5150 my slim 5.25 360k cannot format unformatted disks, because formatted one it does also can read and write, boot, etc. It's is connected to a 3 1/2 720k disk.

It gives me bad track 0 and yes I am using DS/DD floppies fresh from a never used box. One in ten it may format.

Any suggestions ?

SpidersWeb
November 28th, 2017, 08:50 PM
Do you have another drive you could try and format the disks on?
I ask because sometimes even sealed media can go bad - I imported 100 360KB disks from the US last year, and most are unusable with a white powdery goo on the surface.
Those Kao sealed disks that are going around from the US have been great however - got those in a few months back.

Retro Canada
November 28th, 2017, 09:05 PM
Do you have another drive you could try and format the disks on?
I ask because sometimes even sealed media can go bad - I imported 100 360KB disks from the US last year, and most are unusable with a white powdery goo on the surface.
Those Kao sealed disks that are going around from the US have been great however - got those in a few months back.

I found a pattern: leaving the computer off for 20 minutes and formatting the first disk goes, but not the second. Strange huh ?

Could it be any failing capacitor ?

RuudB
November 28th, 2017, 10:50 PM
Rather a part that becomes to warm but after cooling for those 20 minutes is operational again. You could find out which part it is by cooling each part with compressed air (or other means) and try to format a disk. Next question: is it a serviceable part and can it be obtained still.

Good luck!

Chuck(G)
November 29th, 2017, 08:16 AM
IMD's tests should run on a 5150. See what they say.

Dwight Elvey
November 29th, 2017, 10:09 AM
It might be your track 0 LED is failing or there is dust/dirt blocking the light.
Dwight

Retro Canada
November 30th, 2017, 08:28 PM
Problem solved: It was my PC-SPRINT modification. It cannot format in turbo mode. But the IMD works fine. Switching back to 4.77 it formats flawlessly. Funny the documentation didn't say anything about that.

Chuck(G)
November 30th, 2017, 09:33 PM
You'll probably also find that the Sydex utilities work fine. Just like IMD, they use a different method of timing loops. The 5150 BIOS code assumes a 4.77MHz clock and calibrates its loop counts accordingly. Some of the Taiwanese vendors would actually drop the CPU speed down to 4.77 MHz everytime INT13 was invoked, then bring it back up to speed when the routine exited.

SpidersWeb
December 1st, 2017, 04:56 PM
Slightly off topic, but somewhat related.
RetroCanada - I used a 720K version of the GoTek, prepared the USB for 720K images, then hooked it to a 486 with the drive type set to 360KB - and formatted a system disk and booted off it. Works fine as a 360KB drive replacement - but you may need to change the "JA" (Drive Ready signal) jumper between systems.

I don't think the 1.44 version can do the low data rate.

I think you asked about that in another thread. Setting it up was a PITA, but it does work.