1541 Alps Drive, No sync

[joebliksem]

Hi everyone

I have a 1541 Alps drive unit that does not read anything on 2 known working boards. Everything moves as it should but the head sees nothing and does not format. The head resistance checks are all perfect.

What could possibly be the issue? This is making me crazy!

Thanks!

[rubber_jonnie]

Aside form the usual checks, like are all the signals from the drive mechanism reaching the control boards, the best advice I can offer is here: https://dfarq.homeip.net/align-a-commod ... 4a6b7c4a19

[BennehBoy]

There are a few things that could cause this.

* Very bad alignment
* drive spindle motor running too slow or too fast
* poor contact pressure of the disk against the r/w head

The first 2 you can check using Jani's 1541 diagnostic ROM.

The last one can be caused if the prongs on the top metal mechanism are not hooked under the front face plate - I had a drive arrive with them sat on top of it and this didn't allow the head to get a good read on the media.

[joebliksem]

Thanks... this guide helped to improved things a little bit... read some directories at least. Now it's back to zero alignment and it the belt keeps falling off. Definitely some underlying mechanics. I guess I'll have to take it apart. Wish me luck :D

[joebliksem]

Thanks. I think you're on to something on all fronts.

- Testing drive speed returns an error
- I fiddled with it and got some directory reads
- Finally got some (very bad) alignment readings at first
Very bad

20220407_203548.jpg

- The spindle seems very tight when the drive is closed, to the extent that the belt fell off.
- Now back to zero alignment readings

[BennehBoy]

So you get all 0's for the alignment?

If the spindle is only tight when the drive is closed, then you probably need to disassemble the clamp assembly, clean it and lubricate it - be very careful though, there are a lot of parts and they need to go back together in the correct order. I use silicon based oil to lubricate them.

There's some information on here that will help -> https://forum.vcfed.org/index.php?threa ... b.1237433/

[rubber_jonnie]

So you get all 0's for the alignment?

If the spindle is only tight when the drive is closed, then you probably need to disassemble the clamp assembly, clean it and lubricate it - be very careful though, there are a lot of parts and they need to go back together in the correct order. I use silicon based oil to lubricate them.

There's some information on here that will help -> https://forum.vcfed.org/index.php?threa ... b.1237433/

+1 for the clamp assembly. I had a similar issue with an Atari 1050, the belt slipped when the clamp was closed.

Also check the assembly is correct and not putting too much force on the hub when closed.

[joebliksem]

It's alive. Thanks for the inputs!

- Drive needed a new belt (salvaged from dead Newtronics)
- Horribly misaligned, fixed
- Shifted the head stop ever so slightly to create a 0.15 mm gap. This was from one of the pages recommended here.


;)

[BennehBoy]

Great news :dualthumbup:

[rubber_jonnie]

It's a alive. Thanks for the inputs!

:girldance: