help required for 1050 project

[TGB1718]

They only need GND (0V) connected, I usually power the Arduino from it's USB connection.

 

See this for example:- it's for use with SDrive-Max to allow other devices on the SIO bus, it needs pullup as it uses 7407's

The SIO +5V powers the buffer, but not the Arduino.

Edited October 25, 2019 by TGB1718
Add circuit

[xrbrevin]

thanks again, im feeling the need to protect the 1050s ICs after seeing its behaviour..!

[TGB1718]

They only need a shared ground, either side can provide the +5V DC supply but not both 😀

[xrbrevin]

On 10/26/2019 at 2:17 PM, TGB1718 said:

They only need a shared ground

cheers, this is a big help.

the 7504 turned up today, should get the breadboard in the next couple of days and then i can proceed

[xrbrevin]

I got it rigged up on the breadboard with the hex inverter buffer (with pulldown resistors on the inputs).

in the vid i am sending +5v to the inputs on the hex inverter as per the 1050 signals. i needed 2 pairs of hands to film it but it is visible:

DIRC input has +5v already

just out shot at the top i am giving +5v to the STEP input - then the counter increases

i then remove the DIRC +5v and give +5v to the STEP input - then the counter decreases

i then apply +5v to ZERO input and the counter resets to 0

 

in the code i have used HIGH and LOW as logic on the arduino pin behaviour. i will also try using 0 and 1 to see if it makes any difference.

also, i have not used the INPUT_PULLUP in pinmode but i will consider it depending how the 1050 behaves!

 

watch this space... 🤔

 

 

[ochen]

xrbrevin,

 

So I decided to follow along on your adventure, being also of limited abilities, and get my hands dirty.  Some folks already mentioned that control is done by the RIOT chip and they are indeed correct. I dusted off an arduino and soldering iron and can confirm no useful activity on the STEP and DIR pins. Wanna save you some time and maybe you can try another approach. Not sure how difficult that will be though.

 

ochen

[xrbrevin]

thanks, its no so much about the destination, but the journey.

i'll sure to make wrong decisions but i will also find out why they were wrong. i have had no opportunity for formally learn electronics so this is a bold attempt using my own way of learning. we'll see where it ends up. i do like the idea of a 1050 track display unit so this is motivation.

however, i think my drive is unstable and not up to the testing. i will dig out another and proceed...

[xrbrevin]

ok so ive changed drive, interestingly this one uses a WD2797 FDC chip

i connected up just the track 0 function to pin 34 of the FDC just via a pulldown resistor - no diode, and then into the hex inverter arrangement. so far so good! no unusual drive behaviour 😁

 

 

[xrbrevin]

i went on to try various things, culminating in using PINS 19 and 22 of the RIOT chip. this got the numbers to count up on the display during drive activity - great success!

i swiftly shut it down and soldered the wires directly. when i powered it up again, i now just get the fast 'boot error' message - like when there is no disk inserted...! i think i shouldve used diodes 🤔. the drive will not spin up when the atari is powered on but if it is already spinning it will continue to do so. im thinking SIO communication issues or U2/U3.

i used the swap-diag method to find out the problem - change drive, change SIO cable, change atari etc. strangely, the disks i was using to test have become unreadble which gave confusing results. however i discovered my Rana drive needs a new head spring and my Indus needed new chip sockets (!)

so i am currently trying to get it back to normal. i thought it was the RIOT chip but this is ok. i replaced the 6507 and U1 (CA3086) and they are also ok. next thing to do is re-read the manuals & wiring diagrams again and consider U2 and U3.

 

[xrbrevin]

to effect a change and help diagnose the issue, i fitted a happy unit to the fried drive but it didnt fix it.

i then reverted it back to stock - originally it had a USDoubler mod in it - and now the mech does respond to the SIO command from the computer. however, it now produces the 'slow boot error' message instead.

the 1050 diagnostic disk passes the first few tests but fails the drive motor, stepper motor, RPM and zero tests. the drive motor did start but it still reported a fail, the zero test behaviour and noise was not the same as a healthy drive.

i then tried to format a disk and the head steps up to track 39 as normal, then stops. i wonder if this could be the verify or read process failing? i swapped in another mech from a working drive and it does the same.

i have previously had success at repairing 'common/normal' faults but the fault on this drive is due to my intervention so i cannot follow the usual procedures.

can anyone offer any advice where i should start looking?