Tandon 810 won't boot or format

[dukes909]

Hey gang, I have a Tandon Atari 810 drive that I can't get to read or write from. Things that the drive does:

• Powers on
• LED lights come on
• Busy light comes on & motor spins
• Busy light & motor go off after short period
• (power on Atari computer)
• Motor spins
• "BOOT ERROR" (for any good disk that work in a 1050
   

Things I've tried

• Setting the 810 as D2 and trying to format a single density disk. (Drive spins. Head advances bit by bit and then the motor spins & spins & spins forever until I hit BREAK whereupon: ERROR 128. I have to physically power off drive to get it to stop spinning.)
• (A) Disk directory of known good disk from DOS 2.5. (Drive spins & spins & spins. Head retracts & advances a few times. Then: ERROR 144)

I picked this drive up off that big auction site and when I got it and it wouldn't boot or format, it sounded like the speed of the drive was too fast. I screwed up and started trying to adjust the speed on it. I tried several RPM utilities and while the drive will respond to the command of checking the speed from the program (it spins), that is all it does. No speed is displayed in any of the utilities, and I either get an ERROR 139 or ERROR 128, depending on the utility. (I've tried: SPARTA-DOS, Disk-Doctor-II, Disk_Wizard_II).

I'm thinking no communication is getting back to the Atari computer but I am new at this so not really sure.  Other things I've checked and neglected to mention above:

• Checked power from power supply (good)
• Checked board voltages (good)
• Reseated all IC's, reseated them again (no difference)

Tools I have:

• FujiNet
• DMM
• Logic probe
• Digital scope

I have both an 800 and an 800XL to work with from the computer side and I've been looking for a good 810 to swap parts with but haven't had any luck so far finding a matching, working one.

 

Where do I go from here troubleshooting? (I know I shouldn't have messed with the speed! 🙄)

Thanks

Dukester

[Nezgar]

Your observed POST sequence doesn't include any movement of the head? The drive normally moves the head to the "innermost" track 39 when spinning down.

 

When powering up, the head should move to track 0 (outermost track) and then move back to track 39 before spinning down.

 

If you don't see any head movement, see if you can manually move the head forward/back at all with a light push. if not, the stepper motor may have seized up and you might have to give it a turn with some pliers to break it free.

 

Here is a video of what an 810 with a stock ROM looks like when formatting a disk:

• Spin up
• Move from track 39 to track 0
• format track by track from 0 to 39
• verify (read) track by track from 39 to 0
• Lastly, DOS will then write boot sectors, VTOC, and directory sectors - if SpartaDOS, this is only on track 0. If DOS 2.X, this will be on track 0 and ~19.
• Move to track 39 and spin down on idle.

This example video shows a format using SpartaDOS, so the boot/bitmap/directory is only written to sectors on track 0 after the drive returns control to DOS.

 

If you have another working drive, it could be good to know if a disk that was attempted to be formatted in this 810 is readable in another drive, or if the disk is prepared beforehand in the other drive with readable data on it (ie create a test file) if the disk is actually erased, or if the original data is still readable in another drive after an attempted format in this 810.

 

If you've messed with the RPM somewhat, a known good disk formatted in another known good drive (ensure it's single density if formatting in a 1050) you should be able to still read sectors if the RPM is +/- quite a bit maybe even 30+ RPM off? - it's usually the writes that are a concern when the speed is off, as too fast and you risk overwriting the next sector, and too slow you risk read reliability due to increased density. If you can take this "known good" disk and attempt using some RPM test utilities and adjust RPM until mayne you can start getting ANY successful sector reads.

[_The Doctor__]

did you clean and reseat all daughter cards etc as well as all the other stuff, deoxit often wins these battles.

clean the crap out of the head.

and of course the above post.

[TZJB]

19 hours ago, dukes909 said:

Hey gang, I have a Tandon Atari 810 drive that I can't get to read or write from. Things that the drive does:

• Powers on
• LED lights come on
• Busy light comes on & motor spins
• Busy light & motor go off after short period
• (power on Atari computer)
• Motor spins
• "BOOT ERROR" (for any good disk that work in a 1050
   

Things I've tried

• Setting the 810 as D2 and trying to format a single density disk. (Drive spins. Head advances bit by bit and then the motor spins & spins & spins forever until I hit BREAK whereupon: ERROR 128. I have to physically power off drive to get it to stop spinning.)
• (A) Disk directory of known good disk from DOS 2.5. (Drive spins & spins & spins. Head retracts & advances a few times. Then: ERROR 144)

I picked this drive up off that big auction site and when I got it and it wouldn't boot or format, it sounded like the speed of the drive was too fast. I screwed up and started trying to adjust the speed on it. I tried several RPM utilities and while the drive will respond to the command of checking the speed from the program (it spins), that is all it does. No speed is displayed in any of the utilities, and I either get an ERROR 139 or ERROR 128, depending on the utility. (I've tried: SPARTA-DOS, Disk-Doctor-II, Disk_Wizard_II).

I'm thinking no communication is getting back to the Atari computer but I am new at this so not really sure.  Other things I've checked and neglected to mention above:

• Checked power from power supply (good)
• Checked board voltages (good)
• Reseated all IC's, reseated them again (no difference)

Tools I have:

• FujiNet
• DMM
• Logic probe
• Digital scope

I have both an 800 and an 800XL to work with from the computer side and I've been looking for a good 810 to swap parts with but haven't had any luck so far finding a matching, working one.

 

Where do I go from here troubleshooting? (I know I shouldn't have messed with the speed! 🙄)

Thanks

Dukester

 

The drive seems to be having trouble reading the disk. This could just be dirt on the head so do what @_The Doctor__ said and clean the head with isopropanol and a safe cotton bud (one without glue holding it together).

 

 

 

[dukes909]

23 hours ago, Nezgar said:

Your observed POST sequence doesn't include any movement of the head?

Sorry! Yes it does advance the head. Here is a video of it powering on and then after a disk is inserted, trying to boot from it:

23 hours ago, Nezgar said:

Here is a video of what an 810 with a stock ROM looks like when formatting a disk:

Ok, for formatting, I think mine starts at 0 and goes to 39 (maybe), but it never gets does anything else after this except spin:

Atari 810 format attempt

23 hours ago, Nezgar said:

f you have another working drive, it could be good to know if a disk that was attempted to be formatted in this 810 is readable in another drive, or if the disk is prepared beforehand in the other drive with readable data on it (ie create a test file) if the disk is actually erased, or if the original data is still readable in another drive after an attempted format in this 810.

I took a blank disk, formatted it in my working 1050. Then I wrote DOS files to it in DOS 2.5. Moved disk to 810 to try and format it and the format never completes. Eventually it stops spinning and gives an ERROR 138.14  Then I move the disk to the 1050 and try to read it and get an ERROR 144.

23 hours ago, Nezgar said:

If you've messed with the RPM somewhat, a known good disk formatted in another known good drive (ensure it's single density if formatting in a 1050) you should be able to still read sectors if the RPM is +/- quite a bit maybe even 30+ RPM off?

Formatted in a 1050, when moved to the 810, and I try to read it in DOS 2.5 using disk directory, the drive spins, the head moves forward then back, and I get a single "BEEP", then starts over. I have to hit BREAK to stop it. I tried this a couple of times and it varies between the spinning never stopping and sometimes it stopping with an ERROR 144:

23 hours ago, Nezgar said:

If you can take this "known good" disk and attempt using some RPM test utilities and adjust RPM until mayne you can start getting ANY successful sector reads.

i tried a couple of different RPM test utilities and none worked. Almost all spun the 810 drive, the head moves forward then back (just like previous example), then a single "BEEP", repeats, and eventually ERROR 144.

Edited June 27, 2023 by dukes909

[Nezgar]

21 minutes ago, dukes909 said:

I took a blank disk, formatted it in my working 1050. Then I wrote DOS files to it in DOS 2.5.

Can you confirm you used the "P. Format Single" option in DOS 2.5? otherwise the regular format option "I." will format the disk in Dual/Enhanced density, which is unreadable by an 810.

 

21 minutes ago, dukes909 said:

Ok, for formatting, I think mine starts at 0 and goes to 39 (maybe), but it never gets does anything else after this except spin:

OK, we can see in your video that it indeed goes through the motions of formatting tracks from 0-39, but then gets stuck when it tries to verify on track 39, supporting the evidence that it can not read anything back.

 

Can you try cleaning the head? Use a little isopropyl alcohol / rubbing alcohol on a q-tip or fine/microfibre cloth to clean the ceramic head underneath the pressure pad and wipe it clean with a microfibre cloth. Then repeat the tests again.

 

21 minutes ago, dukes909 said:

Then I move the disk to the 1050 and try to read it and get an ERROR 144.

OK this at least indicates the erase component of head is at least partially functioning, if the pre-existing content was trashed by the 810 format.

 

One other thing to try when trying to read a disk, or even at the phase of the format when it reaches track 39, try applying a tiny bit of downward pressure on the pressure pad with your finger to see if it helps get a sector read, or if the format progresses any number of tracks backwards from track 39 with that pressure applied... If so, you might need to adjust the pressure spring to another one of the three "slots" , or some other adjustments to tighten the spring (ie inserting something in between the spring and the pressure pad arm like a small piece of eraser, etc)

[dukes909]

3 hours ago, Nezgar said:

Can you confirm you used the "P. Format Single" option in DOS 2.5? otherwise the regular format option "I." will format the disk in Dual/Enhanced density, which is unreadable by an 810.

Ooof a mistake on my part as back in the day I only had DOS 2.0 so not familiar with 2.5. In any case formatting with option P. and then trying to read it on an 810 gives the same result:the drive spins, the head moves forward then a quick back and forth a single "BEEP", then starts over. I think it does this 3 or 4 times before an ERROR 144.

3 hours ago, Nezgar said:

Can you try cleaning the head? Use a little isopropyl alcohol / rubbing alcohol on a q-tip or fine/microfibre cloth to clean the ceramic head underneath the pressure pad and wipe it clean with a microfibre cloth. Then repeat the tests again.

Cleaned, wiped with microfiber cloth: same results, unfortunately! 😕

3 hours ago, Nezgar said:

One other thing to try when trying to read a disk, or even at the phase of the format when it reaches track 39, try applying a tiny bit of downward pressure on the pressure pad with your finger to see if it helps get a sector read,

Doesn't seem to help! Same results; won't read for checking directory and won't finish the format.😕

 

BTW Thank you for helping so far!

 

Dukester

[dukes909]

On 6/26/2023 at 5:41 PM, _The Doctor__ said:

did you clean and reseat all daughter cards etc as well as all the other stuff

Yep, took them all out, and the IC's.

[+kheller2]

Well then it’s time to use the FSM to troubleshoot the read circuits.  
We know the drive responds to commands, and that it can at least erase/damage existing working disks if you format them in the 810 correct?

 

Although you do have me wondering if you format a disk in the 810 (and the read verify fails) if that disk has sector structure that could be used on a working drive.   You would need a sector copier or editor to see.  I’m just curious about when that gets laid down.   It is probably irrelevant to the problem at hand. 

[dukes909]

2 hours ago, kheller2 said:

Well then it’s time to use the FSM to troubleshoot the read circuits.  

So if I'm looking at correct manual that would be:

• Check A109, pins 7,3,2 for correct waveforms
• Check / replace A110 
• Voltage levels (already did this)
• Check Z104 pins 1,3,4,11,13 for correct waveforms
• Replace as needed: Z101, Z103, Z104, Q102, Q103, Q104

Does that sound correct?

2 hours ago, kheller2 said:

We know the drive responds to commands, and that it can at least erase/damage existing working disks if you format them in the 810 correct?

Yes, that's right.

Thanks!

[+kheller2]

Yup.

 

[dukes909]

18 hours ago, kheller2 said:

Yup.

 

 

On 6/28/2023 at 9:24 AM, dukes909 said:

• Check / replace A110 
•  

Well, mine doesn't have an A110 anywhere so that's a no-go..I'm thinking the field service manual is not the correct one for my model? I have a Revision C analog board.

[+kheller2]

It's on the rear board.

[dukes909]

13 hours ago, kheller2 said:

It's on the rear board.

I think mine is a newer power supply board; it does not have A110. The waveforms on the other chips check out...now what!?

[TZJB]

3 hours ago, dukes909 said:

I think mine is a newer power supply board; it does not have A110. The waveforms on the other chips check out...now what!?

 

Could you please attach an image of your rear board?

 

Normally A110 is a transistor array similar to A107 and A111.

 

[TZJB]

Just found where I downloaded my FSM:-

 

http://blog.3b2.sk/igi/file.axd?file=2012%2F7%2FAtari+810+Service+Manual.pdf and https://www.jsobola.atari8.info/dereatari/literatdere/810fsm.pdf

 

I think that you may have the Grass Valley upgrade and I don't have a FSM that includes that. https://www.best-electronics-ca.com/8-bit_.htm

 

 

Edited July 1, 2023 by TZJB

[+kheller2]

2 hours ago, TZJB said:

Just found where I downloaded my FSM:-

 

http://blog.3b2.sk/igi/file.axd?file=2012%2F7%2FAtari+810+Service+Manual.pdf and https://www.jsobola.atari8.info/dereatari/literatdere/810fsm.pdf

 

I think that you may have the Grass Valley upgrade and I don't have a FSM that includes that. https://www.best-electronics-ca.com/8-bit_.htm

 

 

REV 2 of the FSM should have it....

At least in the Tech tips section.   Anything in here work for you?

 

 

Atari_810_Disk_Drive_Service_Manual_Rev_2.pdf

 

But I now see that Best has a REV 3 edition... hmmm...  I never knew that.

[dukes909]

3 hours ago, TZJB said:

Could you please attach an image of your rear board?

 

 

[dukes909]

57 minutes ago, kheller2 said:

REV 2 of the FSM should have it....

At least in the Tech tips section.   Anything in here work for you?

That's the one I've been using. Only thing I see is swapping data separator board with a known good one, which I don't have.. 🤨

 

59 minutes ago, kheller2 said:

But I now see that Best has a REV 3 edition... hmmm...  I never knew that.

Interesting, I may have to call and order that! 

[+kheller2]

And of course three versions of that board.  Sheesh

MyAtari on eBay has R3 FSM for about the same with shipping.  

[TZJB]

1 hour ago, kheller2 said:

REV 2 of the FSM should have it....

At least in the Tech tips section.   Anything in here work for you?

 

 

Atari_810_Disk_Drive_Service_Manual_Rev_2.pdf 21.53 MB · 2 downloads

 

But I now see that Best has a REV 3 edition... hmmm...  I never knew that.

 

Thanks it looks like the revised 810 is referenced but the circuit diagrams are very rough and difficult to follow.

 

Anyone know of a better version?

 

[TZJB]

1 hour ago, dukes909 said:

 

 

You have a Grass Valley Rev. 2 power supply board. Unfortunately I am having trouble following the diagrams...

 

[dukes909]

4 hours ago, kheller2 said:

And of course three versions of that board.

Wow, did not know about this, thanks.

For what it's worth I downloaded a timing light app for my phone and used the pattern on the flyweel to set the speed to 300rpm and then 288rpm. No difference reading disks or booting from them. 🙄

[dukes909]

4 hours ago, TZJB said:

Anyone know of a better version?

Good question, I'd like to know as well. I wonder what is in the revision 3 version of the FSM or if it is available anywhere for download like R2.

[dukes909]

4 hours ago, TZJB said:

 

Thanks it looks like the revised 810 is referenced but the circuit diagrams are very rough and difficult to follow.

 

Anyone know of a better version?

 

While we're at it, does anyone have a good schematic of the analog board?