Atari 1050 Diagnostics

[svenski]

I've recently got hold of another Atari 1050 which externally was in a bit of a state but has cleaned up nicely.

 

Internally it was surprisingly clean and a missing case screw suggests that it has been opened up before.

 

The drive powers up fine but wouldn't load anything. I've cleaned the drive head and lubricated the drive rails and the head movement on turn on is fine. The drive continues to not boot but I noticed that the head assembly seems to sometimes take a step back past the sensor. I've run SALT and the drive is failing the motor start test, speed (too high) and track zero test. The stepping test works fine. The diagnostic is asking me to move the sensor backward which fits with my observation of the assembly movement when it "takes a step back". The speed diagnostic is reporting zero speed but the pot does not appear to have been touched as it still has the glue on.

 

The motor is obviously working, drive is spinning and speed is obviously not zero. Would the track zero impact the motor start test. Why would SALT be reporting zero speed?

 

Apart from that, I've reseated jumpers, checked against a good 1050 and can't see anything obviously wrong. The only thing I'm yet to do is take the shielding off.

 

 

 

 

[Mclaneinc]

Just adding this to alert @Nezgar as he's Mr Disk Drive on here..

[xrbrevin]

is the drive stock or does it have any mods fitted?

i find that to pass the 1050 diagnostics, the drive has to be stock

 

did you set the zero sensor?

[svenski]

I've set the zero sensor but it passes now in troubleshooting but continues to fail in the diagnostic. I'll have a dive into the shielding when I've got more time - you might be right I was thinking it could have a mod under there.

 

There is a whining noise coming from the main capstan - the belt looks fine, not loose or buckled. 

 

It continues to fail motor start, although does start the motor, and seems to be failing the stepper test although seems quite happy to move in the right direction when starting a burn-in , and it is also reporting correctly that the disk is not single density when trying to do a 10 min burn on an SD disk.

[+Nezgar]

Thanks @Mclaneinc

@svenski First of all, are you working on a Tandon (Made in Singapore) 1050, or a World Storage (Made in Hong Kong) drive? I'm not actually sure if the stock 1050 diagnostics will pass on a WST 1050. (It has modified stepper timing which may throw off the software) But as others have mentioned, check for upgrades or a replacement ROM in your drive as well. Atari's 1050 diagnostics will fail with an ICD US Doubler ROM for instance.

 

You say the drive won't load anything and not even registering an RPM. To register an RPM it needs to be able to read a sector. Usually a drive will still be able to read a sector at plus or minus 10 RPM from the normal 288RPM.  Does the disk "seem" to be spinning about the right speed, comparing the rotational sounds from a working drive?

 

While trying to boot a disk or run an RPM test, try adding a little extra pressure to the top pressure-arm with your finger to see if it helps it get a sector read.

 

If you can get it to read a few sectors at boot, then use RPM utility from SpartaDOS for example...

 

If it's an alignment issue, trying to nudge the head forward or backward a bit while it's trying to read a sector and getting a few to read might help confirm that. Also, if it's an alignment issue, try to format a disk, and if successful it might only be readable in that drive. If it fails, note where it stops - the format pass steps from track 0 to 39, then steps backwards for the verify stage. A failure at track 39 suggests it is not able to read anything back.

 

Check the 5-pin connector at the front right of the drive (J6) is connected properly, and not backwards by chance.

 

If still nothing, before cracking the RPM trimpot, I'd first suggest swapping in a mech from a working 1050 just to verify the motherboard is functioning OK with a known working drive... Or have you done that already if that's what you mean by "checked against a good 1050" ?  Likewise, you could also try the problem mech with a known working 1050 motherboard and let us know the results.

 

Only when you can somewhat reliably get the drive to read ANYTHING from a disk can you then really proceed with diagnostics utilities...

 

[E474]

Hi,

 

  It sounds like the drive has been modded at some point, though people also open drives for cleaning and maintenance, so nothing guaranteed. Best thing to do is to take photos if the PCB, particularly the chips that are normally enclosed inside the "shielding" case, for want of a better word, and maybe post them here for feedback/identification.

 

   Not sure of how you have got things set up, it sounds like you have the suspect drive as Drive 2 (or higher), how does it work when booting as Drive 1 (I assume you checked it was set to Drive 1 when it didn't boot)? 

 

   I have had a 1050 mechanism where the belt was too slack, that reported a good drive with the diagnostics, but it couldn't read disks. Do you have another 1050 that you use to can swap in a mechanism (take photos of the connections first though). Best Electronics in the States still sell 1050 drive belts.

 

   Personally, I think if the drive powers up and spins a disk it's almost certainly fixable, so it sounds like you've bought a (potentially) good drive.

 

   Hope this helps!

   

[+Nezgar]

New 1050 tandon belts also here:

https://console5.com/store/atari-1050-ibm-pcjr-qumetrak-142-floppy-drive-spindle-belt.html

 

and here

https://console5.com/store/fabric-reinforced-belt-for-atari-1050-tandon-tm100-4p-floppy-drive.html

(mentions tm-100 as well, so maybe tandon 810 compatible, not sure)

[svenski]

Thanks for the responses.

 

It is a Tandon mech drive - the only thing I have yet to do is take it apart and open up the shielding which I will do shortly.

 

I've set the drive as Drive 1 and have been running the diagnostics running via an SIO2USB, then unpowering that and turning the drive on. I'm not 100% sure about the belt, there is some noise but the drive appears to spin at a reasonable speed - doesn't seem to struggle.

 

If opening up the shielding doesn't reveal anything then I'll look to swap the mechanisms to see what happens then.

[+Philsan]

 

Likely not related to your problem but I found useful for my 1050 disk drive this Page 6 article

http://www.page6.org/archive/issue_25/page_54.htm

and the utility Disk Speed Check (I put BAS file on a DOS ATR).

 

Disk Speed Checker (1987)(Page 6).atr