dukes909

I replaced all the logic chips on the data separator board with new ones: 1 x 74LS04 1 x 74LS08 2 x 74LS74 2 x 74LS193 No dice. Drive still won't read the disk. Same exact results as before. I haven't checked the signals with the scope but do I need to? So frustrating. 😞

I thought the HC version was not compatible voltage-wise 100% but thought I'd give it a go anyway. Thanks for that information (probably should have asked before trying it though 😛). Looks like all I can do is sit back and wait on the new parts and maybe build a few more test circuits just for the practice. I thought about extending the ground on the scope probe ground with just such a lead but then second guessed myself that they must have made it that short for a reason and didn't want to buy new probes and/or scope due to my ignorance! Thanks again for the help. If I come across a 74LS08 in anything laying around that I can verify works and then test it in the sideboard etc I will post updates. Once I get the new chips in I will post an update as well. I asked before but not sure anyone replied: is it entirely possible (likely) the drive mechanism/head is faulty and causing these problems? Will buy you a pint or your choice the next time I'm over there! Cheers

A201 pin 5 is a real challenge to get to. Using pin 5 as a trigger and then any other pin at the same time with 2 scope probes is probably impossible for me to manage with the vertical orientation of the board and the tight proximity of the actual drive mechanism immediately to the right of it. I may solder up a set of wires to header pins and sockets to be able to remove the board from the vertical position so that I can measure these accurately unless there are other ideas or suggestinons...? (Why are scope probe ground wires so short, BTW?!?) I tried a ribbon cable but the pins on it are not long enough to reach inside the sockets of the sideboard. On a different note, yesterday, for lack of anything else to try, and unable to check these signals above, I started building simple circuits on breadboards to test each chip. The 74LS04's worked as they should. The 74LS08's however all failed (I have 3 from Atari 810's). Thought I had an extra one somewhere but all I have in stock is a 74HC08. Pin for pin compatible so, with nothing to lose, I tried it. Drive still won't read....... Not sure if that means another chip is dead somewhere or there is an incompatibility from using 74HC08 instead of the 74LS08's the board came with. Thoughts? I ordered new chips but it will be a little while before they get here (how I miss the ease of buying things like this locally at Radio Shack!)

Sorry, had to leave computer for a bit while I was editing above comment. Added more info: Double checked - all read +5.03V. Ok...now to figure out how... NoTL866 or the like here; looking at it, it looks like an EPROM programmer?.. not sure if I bought one how to use it to test chips. I suppose I could rig up a breadboard test circuit for each?...may take me a while to build a circuit to test each one. I am thinking of just buying each of the chips that are still available and replacing all. Other than that, is there any chance that it is simply the drive mechanism / magnetic head and all of these other things are A-OK? OK, good that is how I was checking today. Thanks again.

Double checked - all reading +5.03V. Ok...now to figure out how...

Ok here is A201 pin 6same probe on 10x setting. Not much difference. Since the 1KHz test signal is perfectly square I don't think I need to adjust the probes at all? Okay! Shoot! Reading still doesn't work. A206 pin 7 produces this signal, but while the scope probe is attached to pin 7, the drive does not spin up when doing a disk directory command. Nothing happens at all. Then an ERROR 138 is returned. Here is what scope shows anyway for A206 pin 7: And A205 pin 8: Same thing as above. Won't read. Waveforms identical for A205 pin 8. With probe on A206 pin 7, drive won't spin. If I remove probe from A206 pin 7 before ERROR 138 is returned, the drive will spin up and then do its' convolutions and then ERROR 144. Running out of things to change...LOL! Changed A207 and...won't read... But now the waveforms for the IC's above are a little different...? A206 pin 7: (still get ERROR 138 though) Lastly, A205 pin 8: Uggghghhhhhh...............

But that is the test waveform without changing any settings...not from the 810. Next question: should I be using 10X or 1X on the probes for checking signals on the 810 parts - and maybe that is the reason for wonky waveforms? (I told you I am new to oscilloscopes! 🤓)

Do you mean adjust the low-frequency compensation adjustment screw on the probe? I ask because when I check the test waveform built into the scope I get a perfectly square signal: Working on the rest of your suggestions...was away for a couple of days so it's going to take a bit to get caught up. Thanks

J103 pin 27 autoset: and single trigger mode: Reads still fail (🤨), but A201 pin 6 looks better than the one above (I think...not really sure what it is supposed to look like 🤔)??... Single trigger mode:

It looks maybe like multiple failures???.... Pin 6:

As an interesting aside, after the intital format attempt where the head moves towards the spindle, and stops, after about 5-6 minutes (I know, I should have timed it), it starts what looks like the end of a format and then stops again. Then it starts this cycle again after about 5-6 minutes. https://www.youtube.com/shorts/u1S8zTP5s-0

I know but @TZJB said "wait for failure". I thought eventually it would return an error.

After 20 minutes I hit BREAK on ATARI; the drive eventually stopped (after about 2 minutes). DOS returned an "ERROR 128". I tried the disk in the 1050 and it doesn't read anything, just the grinding sound and then an ERROR 144. 🤔

Of course you wanted 2 adjacent pins checked on the bottom side of that chip at the same time! Just kidding. That was quite a challenge but I think I got it. Yellow 26, purple 27.. Autoset on the scope: and then single trigger mode: Horizontal scale widened: \ Formatted in 1050 using DOS 2.0. Wrote DOS files to it in 1050. Booted to verify - good. Started "Format" in 810.... now 10 minutes have elapsed, drive is still spinning and no error returned in DOS so far. How long do I wait?

Good catch. Unfortunately mine are already 1.4K's. Working through the steps in your next post now.

Ok I tried it again with the other sideboard I have and it looks like the same results. Drive trying to read: and a single edge triggered shot: However, when trying to do a format on this drive, I get something remarkably different on pin 38: But the format never completes. The head moves towards the spindle hole formatting (at least what I remember formatting sounding like), then when it gets near to the spindle, it just spins and spins and spins and spins.... I have to power off the drive for it to stop, and the disk is not formatted properly. Beginning to give up hope on this drive. 😞

I tried one of the 2 6532's from the 850 in the 810 and same results: won't read anything off the disk and won't format either. I don't have a copy of the CPS 810 cartridge. Is there an ATR I can download to try booting off the FujiNet device? For some reason I thought cartridge images weren't possible to boot off of? I'm still learning FujiNet. Even if I had it, reading the description on Best's page: "(requires an Oscilloscope and 5 1/4 Alignment Disk and Stepper program)"... I have the scope but no idea where to get the alignment disk and stepper program..? Looks like this requires the CPS 810 cartridge...

I have both! The 1050 is the only working drive I have right now so would rather not possibly mess it up, lol. I have an 850 I never hooked up so I don't know if that would be a good swap but I would rather try that first. Now to find it....lol

Ok I redid this with logic probe set to TTL and drive on but at rest. Readings much different: Pin 24 scope pic: A204, same pin (24): Z101, pin 11: Pin 38 (2 snaps):

Is that the 6532?

Ok I will do this again with the drive at rest and with TTL selected on the logic probe. I'll check this one and the clock line with the scope as well. Thanks again!

Ok, with mine set to CMOS and with the drive attempting a read, I get:

My mistake, I meant Z101B pin 1! Ok, I have a logic probe and can do this, maybe even get the other 20 pins if I move the analog board out of the way. What I don't know is - are these logic readings taken during the drive at rest or while it is attempting a read? Also mine says FD1771B-01 which I assume is what you are referring to "FD1772"...? Is this chip CMOS or TTL? I can't tell from the datasheet and my logic probe has a switch I have to choose from one or the other.

Ok mine is the revision C sideboard that has the data separator board piggy-backed onto it, connecting via what is marked on the board as "A105" but on the schematic in the FSM r3 as J103. First 2 scope pictures are of Z101B (pin4) read attempt, then with drive at rest. Second 2 scope pictures are of Z101 pin 11 read attempt, then with drive at rest. Third set is at pin 27 of J103 (where Z104 pin 11 leads to). I have -5V at pin 1 of J103, +5V at pin 21, and +12V at pin 40. On the daughterboard (data separator board), the pins on the chips are much more difficult to get to unless I rig up some header pins to connect from the power supply board to the sideboard. I looked at the SAMS Computerfacts at one time but it seems to be for a much earlier model than the one I have (I think theirs is the MPI drive and mine is the Grass Valley board Tandon). Thank you for your continued help with this!

The first image is the signal while the drive is trying to read the directory from DOS 2.0. The second image is the signal once DOS "gives up" and returns an ERROR 144 and the drive is not doing anything at all, so..is this a clock signal? I don't know what I'm looking at here. Yes to a header pin then wire then another header pin on the power supply board where it appears to go to the sideboard assembly pin 23 and then Z104? The last 2 images are signals at pin 1 of Z104 during an attempted read, then the same pin while the drive is at rest.