New project: An ACT Apricot F1 "barn find"

[derkom]

That really is amazing. I've tried looking for all those numbers on multiple search engines, and this floppy drive simply does not exist.

I think this Apricot came from a parallel universe!

[stephen_usher]

I know! Amazing isn't it?

After putting the drive back in the machine obviously the alignment went out again. So it's not working again. Oh well.

[stephen_usher]

Re-visited the F1 drive again after discovering that the system gives error 35 if there's no drive 1 (as opposed to drive 0).

Switched the drive ID switch and the drive is now recognised correctly after the capacitor replacement. However, the motor isn't running. So one step forward. At least the electronics work.

(OK, spoke too soon, now gives error 35 again and recognises the drive as only 315K. It changed when I was flipping the media detect switches.)
(P.S. I think it was a coincidence. Something else obviously went ga-ga at that same time.)
(P.P.S. I think I should replace the capacitors on the daughter board now.)

[stephen_usher]

I think I've excluded the daughter board from the main failure issue as the drive behaves the same way with it disconnected.

If it's been turned off for a while it manages to run its initial diagnostics and move the head back to the track zero (if it's been off long enough) but then crashes. The longer the drive hasn't been powered for then the longer it takes until it fails.

This *feels* like a capacitor problem as in something's breaking down after a time period.

I've replaced all the cylindrical electrolytics so it can't be them. Any more ideas? Here's the main board:

IMG_2315.jpg (260.93 KiB) Viewed 3220 times

[rubber_jonnie]

I think I've excluded the daughter board from the main failure issue as the drive behaves the same way with it disconnected.

If it's been turned off for a while it manages to run its initial diagnostics and move the head back to the track zero (if it's been off long enough) but then crashes. The longer the drive hasn't been powered for then the longer it takes until it fails.

This *feels* like a capacitor problem as in something's breaking down after a time period.

I've replaced all the cylindrical electrolytics so it can't be them. Any more ideas? Here's the main board:
IMG_2315.jpg

Are any of the pots capacitors? Or are they all resistors? Have you checked closely with a microscope for tiny spots of corrosion? Also, are any of the components getting warmer than they really should?

Are you able to test any of the LS logic in place using 5v for power and inputs?

[stephen_usher]

I'm afraid you can effectively see in that photo everything I can. I'm not sure what those blue and grey blobs are.

If the worst came to the worst I was going to try extracting each 74* chip and testing them in the EEPROM programmer, which has logic chip testing functionality, or just replace them anyway.

[stephen_usher]

I wonder if those blobs are tantalum capacitors... If so then they wouldn't react well to damp conditions.

P.S. Oh, they are! I've found the values... modern replacements ordered.

[rubber_jonnie]

The variable items look like resistors based on the silk screen, so probably ok.

[rubber_jonnie]

The variable items look like resistors based on the silk screen, so probably ok.

I wish I had my TL866 Pro right now to test the heck out of the BBCs logic chips!

[PhilC]

The variable items look like resistors based on the silk screen, so probably ok.

May be worth giving them a tweak back and forth in case you already haven't due to the opportunity of corrosion getting to their tracks and the wiper.