naujoks

I should point out again that now the drive is continually spinning and doesn't stop an more.

I doubt it's the track 0 sensor. If it is faulty, the rw head would still try to move. Mine doesn't move at all. Not sure if it's the FDC, as far as I can see the FDC's task is data transfer. We haven't got to that stage yet. Also, the repair manual doesn't mention it as a part to check when there's problems with the stepper.

I now measured the windings of the stepper. Some of the values are a bit high (they're supposed to be 33 ohms): 1-6 33.5 ohms, 6-3 36 ohms, 2-5 38 ohms, 5-4 33.8 ohms. Maybe not catastrophically too high though? Also to note that with the 6507 and 6532 now confirmed working and in new sockets, as well as an EPROM with the correct jumper settings, the drive now spins up and it keeps spinning.

I did that now. See above.

Also, using reading the PROM using the 2732 setting with the programmer is probably not the right thing to do and the reason why I got erratic results. Can I read the content somehow?

Original 6532 and 6507 confirmed to be working now. Together with the newly burned EPROM, this results in the drive continually spinning. Here's another bit of information I just discovered: when I switched on the drive and pushed the r/w head a little bit, it was firmly locked in place. When switching off the power, I can easily move it. I also noticed that when switching it on, it moves a tiny bit, it just locks it in position and doesn't move. Between 6532 and 6507 there's another IC which I don't recognise. What does it do? I guess if the FDC is toast, I can only confirm it by plugging in another one. I don't have one of those though. This is my first and one and only 1050 drive.

Ok I'm getting this vital info bit by bit lol The "jumpers" were soldered into place, so I replaced them with proper jumpers. Now the spindle starts running again and then stops, then starts again etc. With the original 6537 in, the motor doesn't stop spinning. I should find out if the 6537 & 6507 are ok. Can I put them in my VCS 2600? I learned I can use the VCS 2600 parts in the 1050, but what about the other way round?

It's PROM as far as I can see. I tried to google what's written on it but it didn't come up with anything.

I used 2732 eproms. It wasn't mentioned that I need to change a jumper. Do I?

It's a Tandon alright. I've just replaced the sockets for the ROM and the 6532, but no change.

I'll look into it. Meanwhile on to the mystery of why my EPROM doesn't work at all. I burned 4 EPROMs from 2 different batches now, just to make sure there's no problem with the EPROM, but none of them made the motor spin up. It only does that with the original ROM, but as mentioned, that ROM is half full of FFs (if I read it out correctly). Are there different ROM versions around? What else could explain this?

Are these test points inside the stepper? Will I have to open it up?

I'm getting 4.95v at the ICs, which is good enough, no doubt. The underside of the PCB is squeaky clean. I checked for cold solder joints. I wanted to read the content of the ROM, but since I can't figure out which kind of type this ROM is, I chose 2732 (was that ok?). Weirdly, the first half of the ROM is just FFs. Even more weird is that when I put in my self burned 2732 EPROM using the ROM image provided above, the drive doesn't spin up at all. When moving the r/w head manually, the stepper motor appears to move easily, so I don't think it's stuck, and hopefully also not corroded.

I looked at some picture of 1050s. All connectors seem to be in the right order. So the question is, why is the r/w head not moving?

So weird, after more chip swapping (including a new EPROM, with which the drive wasn't spinning up at all) and ending up with the original chips in the drive, it now spins up 2 seconds and then stops, the LED goes out, just like it should. The r/w head however hasn't moved one little bit though, so maybe that's the problem now?

Is that connector J6? It's visible on the other picture I posted.

I checked the voltages at the regulators, and they are fine. I swapped the RIOT and 6532 with two chips from a working 2600 Jr - assuming, that these are the same chips. There's no difference though, only when I replace the 6532 sometimes the spindle motor doesn't start at all, sometimes it runs non stop (and the LED is lit at that time). Pictures attached. I guess I should try replacing the ROM. Which IC is that?

There are no signs of burned out parts. The caps look good, no bulging or leakage. Can you tell me where I can measure the 5v and 12v on the board? I don't have the schematics.

I'll send a picture in a bit. Meanwhile, can I swap some of the ICs? I have 6507 from an Atari 2600 which I could try. Can I burn a new ROM? I couldn't identify the type used.

Correct, the head doesn't move at all, but as mentioned, it moves easily when I push it manually.

I'm getting 10.8VAC from the original PSU, so probably the required 9VAC with load. I don't think the drive has been tampered with before, it's probably just not been used in years, possibly decades.

Yes, the drive was always powered off when unplugging/plugging in cables. One IC had a bit of corrosion, I cleaned that up, the sockets seemed to be in good condition otherwise, even though they're only single wipe. I don't think my cleaning efforts have made anything worse.

Addition: I let the drive sit there for a while, and after 1 minute or so, the spinning up/down cycle stopped. The drive won't load the disks I have (a couple of Infocom adventures): I'm powering on the 1050, pressing the Option key, power on the 800XL, let go of the option key (if I keep it pressed, the self test starts). Incidentally, what is the default position of the drive ID switches?

I can confirm that the r/w head moves easily on its rails (so far it remains stationary though, no movement whatsoever). Right now I don't have the 800XL connected to the drive. When switching on the drive, it displays the described behaviour, regardless of whether there's a disk in the drive or not.

I just picked up an Atari 800XL and a 1050 disk drive. The 800XL seems to work fine, but the 1050 isn't. When powering up, the two diodes light up, the motor is spinning for a couple of seconds, then stops (the LED goes out), and then after a couple of seconds, the motor starts again for a couple of seconds, goes out etc. I've opened up the drive and gave it a visual inspection, it looked reasonably clean. Solder joints all look good. I took out the socketed ICs, gave the legs a good clean with a glass fibre pen, put some deoxit in the socket (and on the connectors). No difference though. Any idea what could be wrong?