exxos's Atari, Amiga & retro forum

Here's a picture showing the 50Hz light strobing on the dials on the bottom of drive B.

stephen_usher wrote: 07 Feb 2024 23:34 Here's a picture showing the 50Hz light strobing on the dials on the bottom of drive B.


IMG_3568.jpeg

They look huge, more like 8" drives.

Are the dead spots due to the belt, or is it a problem with dry grease in the bearings? If so could you put in some light oil and keep them spinning to break up the dry grease?

The motors aren't even trying the turn (there's no hum or jitter from them) until I put some pressure on them. Once they kick in they go fine. I s'pose one set of windings in the stepper motor cold have gone, but I don't know it they're even stepper motors.

They've been oiled and spinning for most of the evening.

Right, plan of action to test the A drive... Use a BBC Micro.

I should be able to hook these drives up to a BBC and read 40 track disks. If that works then I know that the drive is working OK.

I can test if the disk image(s) I have are OK using a Gotek and converting the IMD format files into HFE files. It will also verify that the Kaypro's floppy interface is working correctly.

That will get rid of most of the variables, leaving just the writing stage from the Win98 PC.

stephen_usher wrote: 08 Feb 2024 09:15 Right, plan of action to test the A drive... Use a BBC Micro.

I should be able to hook these drives up to a BBC and read 40 track disks. If that works then I know that the drive is working OK.

I can test if the disk image(s) I have are OK using a Gotek and converting the IMD format files into HFE files. It will also verify that the Kaypro's floppy interface is working correctly.

That will get rid of most of the variables, leaving just the writing stage from the Win98 PC.

Good luck!

"Drive A" doesn't work properly. The motor seems very weak for a start.

I found a whole load of broken joints on the motor power board but even after reflowing those it made no difference.

I reconfigured "Drive B" to be a "Drive A" and that worked fine after a few tries getting the head stepper to run. Loaded Elite no problem.

So, I've put the drives back onto the Kaypro with them swapped. Now the system starts to boot but freezes after printing the banner.

'Scoping the data bus after the system has crashed all the lines except for the one for U26 have a very similar pattern. The U26 data line is going hell for leather.

When the floppy drive motor stalls and the machine is waiting for the data all the data lines except the one for U26 are high. The one on U26 is mostly low with a short spike up to 5V every 1600uS. Doesn't look right at all.

All the memories are Intel 4164 equivalents so I have spares, but I'm not looking forward to desoldering that chip as all the solder and chip legs are tarnished and slightly corroded around there so desoldering is going to be an issue. Anyway, it'll have to wait until the weekend now.

OK, it can't be the RAM chip as it's on the Data-in line and that's separated by the 8216 transceiver. The spike must be on the data bus D1.

On the "Drive A" front, it's probably the servo board which has a problem, either the LM2917 or the TIP110 or both.

Sounds like good progress, very much looking forward to seeing this running.

@stephen_usher how's it been getting hold of service manuals for those drives? I've had a couple I had to fix and lets say Unicorn Poo was more easier to find.