Attempting to repair a 1050 Disk Drive-no activity light no motor/head spin

[repetto74]

Hi Guys,

 

Got a 1050 DD for a few bucks sold as non working. I received today a 9V AC 2.1 amps PSU and can start my troubleshooting.

 

The power led is coming up but that's all. No motor spinning and no movement of the R/W head mech. The activity light is off also.

 

What I have tested for the moment is the voltage at the 7805 and 7812 which are both fine and read +5V and +12.05V.

 

I picked up also a spare board untested for a cheap price. Swapping the board with the second and I have now the drive mech coming alive, the disk motor spins briefly then the head mech will step forward and then back to the track sensor and stops. Then the activity light turns on with the disk motor spinning, then all off and on again in a repeated pattern. Is this an indication of a fault code?

 

I will keep this board for the moment and try to repair with this one. For the first board I may think one chip is fried and does not send commands to the drive mech but I will see that later. Let's try to make a working drive with what I have :-)

 

Here is a video of the 1050 in action

 

Thanks

Rick

Edited September 4, 2018 by repetto74

[repetto74]

As you can noticed from the video the R/W head is bumping at the end of the track rail (like some of the 1541 Commodore Disk Drives) but I do no think this is a normal behaviour.

[+Nezgar]

The head stepping outwards (towards track 0) bumping against the end tells me the track 0 sensor has an issue.

A previous thread claims this is a drop-in replacement:
https://www.newark.com/optek-technology/opb842w51z/slotted-optical-switch/dp/73K1112

and B&C ComputerVisions / myatari.com used to have these parts listed (You have a Tandon mech). They recently removed their price listings from the website, but you can try e-mailing. However, it took over 2 weeks for me to get a response a month or so ago. You can try Best Electronics too, but they have a minimum order and you probably want to wait until you have some other things to order too.

PRA048 TRACK 0 SENSOR TANDN 1050 10.00
PRA047 TRACK 0 SENSOR WORLD 1050 10.00

Now for the controller board that is lighting up, but not functioning at all, you can verify if it's one of the 5 main IC's by swapping them from the 'dead' board into the good one, and verify it powers up the same way each time.

 

Start swapping and testing these one at a time into the controller that currently responds. I believe they are socketed on all 1050's.

- 6507 CPU

- 6810 RAM

- 6532 RIOT (far right)

- ROM (to the left of the CPU)

- Lastly WDC controller (far left)

 

If the problem is one of these, most of them can still be easily sourced.

[xrbrevin]

the track zero sensor has an adjustable plastic block on the back end to act as an additional physical barrier. if this is set incorrectly it will obstruct and prevent the head's plastic tang from reaching the sensor.

leave the forward screw tight but loosen the rearward screw just to check if this is the case. power it up and see

 

 

also, you could put something (e.g. piece of cardboard) in the sensor to activate it to see if the drive's behaviour changes

Edited September 4, 2018 by xrbrevin

[repetto74]

Ok so I have swapped all the main chips one by one and tested (FDC,CPUT,6532,ROM and RAM). I had exactly the same problem for each swap except when I swapped the RAM 6810 and there I had the dead drive mech and no activity light of the first board :-). So this RAM is bad. What I will do is to use the RAM of the second board into the first board and fire it up.

In the picture enclosed this is how I found the main connectors hooked up. Someone may have put his hands there before so can I be sure they are correctly hooked? I have a doubt when I see J10 and J11 not sitting close to each other.....

 

By the way thanks for the park sensor supply but I am located in Europe :-(

 

 

 

 

Edited September 4, 2018 by repetto74

[xrbrevin]

the PCB is marked with the vairous plugs numbers - some markings are in front of the pins, some are at the rear

the Happy 1050 installation pdf file has an image of them too

 

looking at your image id say 10 & 11 are in the wrong places and need swapping

Edited September 4, 2018 by xrbrevin

[repetto74]

Job is done! Sorry I did really waste my time and yours here . I have checked on the service manual and it appeared in fact that many of the connectors where mixed and connected the other way around!! I have never fixed a 1050 drive this is my first but as you can see the drive now boots good . At least I found the fried RAM on the first board.

I will run a diagnostic test now I assume there are maybe some tuning to be done. I will try to load the test from my SIO2SD device and then hook the 1050 drive with the SIO cable

Maybe we have another 1050 taken out from the grave :-)

[Fred_M]

Great job! Your gamble payed out

 

You found out that the RAM was bad This gives me hope that the other one can be repaired too

 

Good luck with this bargain

Edited September 4, 2018 by Fred_M

[repetto74]

Hi Fred,

 

Thank a lot! Yes luckily it was just the 6810 RAM chip which was causing the problem + my mistakes at a certain point where I mixed the connectors but all looks fine now!

 

PS : By the way the cassette deck player 1010 is fixed also. Your new belt is apparently working good

Edited September 4, 2018 by repetto74

[Fred_M]

which one did you use? The flat one or the square one?

[+Nezgar]

Good to hear you found the issue. I've had the exact same problem in two drives in the past.

I have had good success with 6810's from this seller in Switzerland in the 1050:

https://www.ebay.com/itm/201459455417

[repetto74]

which one did you use? The flat one or the square one?which one did you use? The flat one or the square one?

 

 

I used the square one. The flat one was a little bit smaller and maybe forcing on the main cassette drive. I had some reading issues at the beginning but cleaning the head with IPA fixed the problem :-)

[Fred_M]

I hope the square belt keeps working, because your Hong Kong model needs a flat belt... Thanks for the info!

[repetto74]

Good to hear you found the issue. I've had the exact same problem in two drives in the past.

I have had good success with 6810's from this seller in Switzerland in the 1050:

https://www.ebay.com/itm/201459455417

 

I have a couple of spare for a TI99/4A which uses those rams :-)

 

I have a question now concerning the combination of the 1050 drive and the SIO2SD device. Can I daisy chain them? I mean connect the 1050 as device 1 to the 800XL and then connect the SIO2SD to the drive? How can I boot from the SIO2SD device then? I am asking because I would like to boot DOS 2.5 from the SIO2SD to format a disk and test.

What I did also is to clean the R/W head with IPA. I will not change both regulators as they are outputting just 12 and 5V so they are still good (maybe some fresh new thermal compound). There is a third regulator on the board but I do not know its function.

 

[repetto74]

I hope the square belt keeps working, because your Hong Kong model needs a flat belt... Thanks for the info! 

 

I will keep you posted if something fails

[+Nezgar]

I have a question now concerning the combination of the 1050 drive and the SIO2SD device. Can I daisy chain them? I mean connect the 1050 as device 1 to the 800XL and then connect the SIO2SD to the drive? How can I boot from the SIO2SD device then? I am asking because I would like to boot DOS 2.5 from the SIO2SD to format a disk and test.

What I did also is to clean the R/W head with IPA. I will not change both regulators as they are outputting just 12 and 5V so they are still good (maybe some fresh new thermal compound). There is a third regulator on the board but I do not know its function.

 

You can daisy chain no problem. Only requirement is to either set the physical and emulated drives to unique drive ID's, or have the physical drive OFF during boot, then disconnect SIO2D or dismount the image in D1: when you turn on the real drive using D1: (so they don't both respond to a request for D1:)

 

Or set the 1050 to D2:, and the SIO2SD to D1: for booting. When formatting, you can specify to format drive 2.

 

If I have it right, the third regulator you refer to is a 'Darlington Transistor' which is part of the circuit that doubles the original 9V AC to 18V AC. This is then bridge rectified to 18V DC, and then passed to the 7812 regulator to make 12V DC for the motor.

[repetto74]

Hi Dragonstomper,

 

Thanks a lot for the clarification .Sounds good then. I will try to boot the diag test from the SIO2SD and then connect the 1050 to go through a full check then. Ok so the Darlington should be good also as I have a nice +12V :-).

 

One final question : I am missing two of those rubber fittings installed between the drive mech and the main case screw holes. It is not a big deal if I do not use them but in case any idea with what can I maybe replace the missing ones? :-). I think the main idea behind those rubber rings is to avoid vibrations.

 

 

Edited September 4, 2018 by repetto74

[+Stephen]

Hi Dragonstomper,

 

Thanks a lot for the clarification .Sounds good then. I will try to boot the diag test from the SIO2SD and then connect the 1050 to go through a full check then. Ok so the Darlington should be good also as I have a nice +12V :-).

 

One final question : I am missing two of those rubber fittings installed between the drive mech and the main case screw holes. It is not a big deal if I do not use them but in case any idea with what can I maybe replace the missing ones? :-). I think the main idea behind those rubber rings is to avoid vibrations.

 

 

Spacer / vibration resistance. Honestly, you can use a rubber o-ring as a quick fix for the missing ones.

[brenski]

...or a couple of the rubber legs that go under the corners of the XL/1050 case - spears often crop up on ebay.

 

simply push a hole thru them

[+Nezgar]

One final question : I am missing two of those rubber fittings installed between the drive mech and the main case screw holes. It is not a big deal if I do not use them but in case any idea with what can I maybe replace the missing ones? :-). I think the main idea behind those rubber rings is to avoid vibrations.

Being in Europe this may still be out of the question for you and it's well below the minimum order, but for the record I checked my BEST electronics catalog, and the rubber fittings you mention are listed as:

88-1010 set of 4 - 1050 Rubber grommet - used under the 1050 transport. - $1.00

[repetto74]

Ok thanks I will sort this out and find a suitable rubber ring of same thickness

[repetto74]

Back with news. I am definitely not done with this 1050 drive. I have loaded the Diag Test with the SIO2SD device then connected the 1050 drive with the SIO cable I have for the 1010 datasette (should be the same). First thing I noticed is the activity light staying on longer compared to a power up without the serial cable connected to the 800XL (??). Then I ran the complete test but as the first two test passed all the rest has failed. I have then selected the motor speed but what is worrying me is that I can hear a 3 tone sound repeated all the time and the speed counter stays on "0". I am a little bit lost on what to do as this is my first 1050 drive.

 

 

[+Nezgar]

Ensure ONLY the 1050 is attached to the SIO when running those tests. (NO SIO2SD)

 

Also you need to run those tests with a known good single density formatted disk in the drive. A blank unformatted disk, or no disk at all will fail.

 

RPM could be too high, but I would think most of those tests should still pass.

[repetto74]

Ensure ONLY the 1050 is attached to the SIO when running those tests. (NO SIO2SD)

 

Yes the SIO2SD was disconnected.

 

Good to remind me to do this with a formatted disk. Unfortunately I do have a lot of disks but for the C64 only. I have a bunch of DD disks also but not formatted with Atari DOS.

[+Nezgar]

Boot a DOS 2.0S ATR image from the SIO2SD, then disconnect SIO2SD, turn on 1050, insert disk to format, choose option I. FORMAT DISK. (DOS 2.5 is option P. FORMAT SINGLE)

 

After format, optionally choose option H. WRITE DOS FILES to make a bootable DOS disk.

 

Make a couple while you're at it. The write tests are destructive

 

DOS 2.0S ATR is on AtariMania: http://www.atarimania.com/utility-atari-400-800-xl-xe-dos-20s_15978.html