dzzy1982 Posted January 20, 2022 Share Posted January 20, 2022 My 1050 (that I've had for at least 10 years) suddenly stopped working today ? It's a world storage Hong Kong unit. The mechanism seems fine, drive motor, stepper motor al seem in good nick. Power on seems normal with the usual whirring and seeking noises. All LEDs still working. I have not found any bad diodes or resistors at this point. Started in with the usual checking voltages, 12v seems fine but 5v is measuring slightly low at 4.85v. Is this normal for the unit? My other 1050 is a Singapore unit, so I have nothing to compare it with. I think I remember something about these world storage having the op-amps go bad. What are some of the common failings for these? Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted January 20, 2022 Share Posted January 20, 2022 Before you dig too deep, have you cleaned the heads and also checked the pressure pad ? Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted January 20, 2022 Share Posted January 20, 2022 clean the head, clean the head some more, and when you are done clean the head... clean it again... then move on to checking the amp and the FDC 1 Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 20, 2022 Author Share Posted January 20, 2022 (edited) 15 minutes ago, TGB1718 said: Before you dig too deep, have you cleaned the heads and also checked the pressure pad ? Yes, I started in with cleaning the head and checking the pad. Both seem fine. It acting as if the head's been unplugged from it's header. It was working fine two days ago. It's not like it started getting wonky reads and writes, it just up and died. Edited January 20, 2022 by dzzy1982 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted January 20, 2022 Share Posted January 20, 2022 When you turn on the computer with the drive powered on and configured as drive 1, does the computer jump to "READY" or does it produce "BOOT ERROR" ? (This will tell us if the drive is responding to commands, even if they are NAK's). If you receive BOOT ERROR, do they print faster when the drive latch is open vs closed? If you receive BOOT ERROR's, does it change with a disk in the drive? (ie long pauses between each line printed) - is it any different with a disk in the drive, or without a disk in the drive? If you can get booted into DOS from a working drive or from an SIO2PC type solution, then switch over/attach this drive as d1: can you issue a format command to the drive? The normal/expected motions are sequentially advancing from track 0 to 39 (formatting), then retracting track by track from 39 to 0 (verifying). See if it maybe steps from 0-39, but then errors out when the verify phase starts at track 39. Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 20, 2022 Author Share Posted January 20, 2022 (edited) It does respond to commands, when powered on it tries to read the disk, with the latch open it gives a fast boot error, with it closed, a slow one so it seems the controller is working. It doesn't seem to matter if there's a disk in it or not. It's like it's not seeing the disk at all. Do heads go bad on these? Like I said, it behaves as if the head has been unplugged from it's header on the board. I have a scope I could hook up to it, I should be able to get something right off the header coming off the head, no? And there should be a test point after the op-amps to connect a scope as well? I need a service manual. Edited January 20, 2022 by dzzy1982 spelling Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted January 20, 2022 Share Posted January 20, 2022 If you have another drive, use it to load DOS and format a disk in your 'bad' drive. Usually, it is a speed or alignment problem, not the electronics. (or, power supplies...) Bob 2 Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 23 minutes ago, bob1200xl said: If you have another drive, use it to load DOS and format a disk in your 'bad' drive. Usually, it is a speed or alignment problem, not the electronics. (or, power supplies...) Bob I did try formatting a disk with it, it gets halfway through, pauses for a second and then retries quite a number of times before throwing an error 173 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted January 21, 2022 Share Posted January 21, 2022 so loaded up with a good drive, did you try an rpm program to see if the bad drive reads and what it's rpm is? Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 (edited) Oh man, it just started working again spontaneously! There must be a bad solder joint somewhere. Either that, or a hostile spirit has taken up residence inside my floppy drive. edit: I spoke too soon. Now it's not working again. Too weird. Can't get an RPM reading off it, which was working before. I'm going to pull the board out and check for cold joints. Edited January 21, 2022 by dzzy1982 Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 This does not look factory ? What could this be? The red wire goes to pin 4 of the LM311 op amp at U24 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted January 21, 2022 Share Posted January 21, 2022 I've used the rpm tester while touching and moving about on the pcb and connector to discover flaky stuff before... there's no shame in it. cold solder joints, bad sockets, bad connectors and wires... even bad grounds discovered in that way... no different than freezing spray or heating something to find a bad chip or transistor etc.. Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted January 21, 2022 Share Posted January 21, 2022 The added wires were there all those years, right? Sounds like bad belt or such. Tap the speed adjustment pot a little. Bob Quote Link to comment Share on other sites More sharing options...
Tillek Posted January 21, 2022 Share Posted January 21, 2022 3 hours ago, dzzy1982 said: Oh man, it just started working again spontaneously! There must be a bad solder joint somewhere. Either that, or a hostile spirit has taken up residence inside my floppy drive. edit: I spoke too soon. Now it's not working again. Too weird. Can't get an RPM reading off it, which was working before. I'm going to pull the board out and check for cold joints. Guess the hostile spirit went out on a beer run. Sorry man. If you need another, I know BF2k still has a bunch he's trying to offload. Quote Link to comment Share on other sites More sharing options...
1050 Posted January 21, 2022 Share Posted January 21, 2022 3 hours ago, dzzy1982 said: This does not look factory ? What could this be? The red wire goes to pin 4 of the LM311 op amp at U24 Actually it does look exactly like some factory busy work for the fix it guys - there will be no book reading or food fights on my watch. http://www.atarimania.com/documents/atari-1050-field-service-manual.pdf http://www.atarimania.com/documents/Atari_1050_Disk_Drive_Sams_Computerfacts_Technical_Service.pdf Wish I could help more, see if you can grab a 5 volt sample if it ever comes back from the dead again? 4.85 might barely (3%) be within tolerance, but if it's better than that when it's working, I would change the Q7 7805 responsible - I might do that anyway. I can't recall an intermittent issue ever before this one and of course they are the worst to discover the reason behind it. Two 3086 chips U21 and U1 are known to get weak or quit outright. Will be watching for more of the story. Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted January 21, 2022 Share Posted January 21, 2022 Just in case its oxide on one of the many plugs, I'd give it a squirt of deoxit (or similar), take them off (remembering the order and orientation of one of them), give them a squirt and a brush. Won't do any harm either way.. 1 Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 (edited) 8 hours ago, 1050 said: Two 3086 chips U21 and U1 are known to get weak or quit outright. Will be watching for more of the story. After some more testing and looking at the service manual, I am starting to think that it's the U1 chip. The drive is responding to all commands and otherwise working normally, there just no data coming through. So that narrows it down greatly unless it's a bad head, which is doubtful. If it was a bad PIA, would it respond to commands normally? Could a bad U1 be responsible for the low voltage on 5v? Edited January 21, 2022 by dzzy1982 Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted January 21, 2022 Share Posted January 21, 2022 Amongst other things, the PIA controls the motors, so if it was bad you wouldn't see head movement or the motor spinning Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted January 21, 2022 Share Posted January 21, 2022 9 minutes ago, dzzy1982 said: If it was a bad PIA, would it respond to commands normally? Almost certainly not, though that would depend on the failure mode of the PIA. Seems highly unlikely that it would respond properly, though. Since you have one working drive and one non-working, both of which have been tested with their drive number switches set to either 1 or 2, it's likely the drive itself. Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 15 minutes ago, x=usr(1536) said: Almost certainly not, though that would depend on the failure mode of the PIA. Seems highly unlikely that it would respond properly, though. Since you have one working drive and one non-working, both of which have been tested with their drive number switches set to either 1 or 2, it's likely the drive itself. I was actually referring to the PIA (U7) within the 1050 itself. I think I might pull that U1 and see if voltage comes up a bit. 1 Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted January 21, 2022 Share Posted January 21, 2022 But if it briefly burst back to life and then died again soon after, then I'd have thought that ruled out a damaged IC? Quote Link to comment Share on other sites More sharing options...
dzzy1982 Posted January 21, 2022 Author Share Posted January 21, 2022 That "IC" at U1 is actually a transistor array. Funny that it's not labeled as such, seems they get a bit wonky before finally checking out, so that could explain the zombie-like tendencies of springing back to life seemingly without explanation. 1 Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted January 21, 2022 Share Posted January 21, 2022 old chip sockets can be problematic, check continuity before condemning the chip Quote Link to comment Share on other sites More sharing options...
1050 Posted January 21, 2022 Share Posted January 21, 2022 So hard to say at this time. Around here U7 is more commonly known as the RIOT chip, Sam's photofact people aren't Atari people so what can I say? When it goes bad typically (and they do) it's a nonfunctional unit to a completely fixed deal. So still zero on the intermittent symptom. U21 is responsible for creating the gain from the head on reading and also the bias and erase power to the head during format/recording IIRC. I would suggest a complete cleaning of the removable chips from sockets to carefully wire brush their legs, application of deoxit and reinsert into sockets at least 3 times to eliminate a cruddy socket from the issues it still could be. Shoot the drive switches with deoxit and work the devil out them while still wet, let dry and work the devil out them again as they will go bad right in the middle of command/data communications giving wild evidence that they are good when they are very dirty instead. Change both 3086 if you are going down that rabbit hole and hopefully the intermittent condition will resolve itself at some point giving an indication of where that issue actually is? And my bad on the intermittent issue, there was a case of dirty sockets just recently cured, I have now been able to recall. He posted quite a string before he did the deoxit thing with the sockets and bailed off the thread immediately when it started working again. It really can be that simple and no need to apologize for overlooking what are usually the first steps to do - they just wind up being the last steps instead and in life stuff happens. It happens to all of us too. Yes the 3086 is just five transistors, but back in the day they used kinda poopy silicone to make them with so any number of things can and do go wrong with them. Thompson/RCA/Harris were making them with the good stuff, ecg912 is their number for it. MC3346P, nte912, and ha1127 are other numbers used for the same 3086 chip. Quote Link to comment Share on other sites More sharing options...
StickJock Posted January 21, 2022 Share Posted January 21, 2022 (edited) I had a 3086 go bad on my 800. Everything worked, except that the volume was really, really low and the display had no color. Looking at the schematic, the transistors in the 3086 were in both the audio & video path, so I plugged in a new one and both issues were fixed. Of course, I had cleaned all of the chips & the boards & sockets and everything first - used an entire can of electronics cleaner - to no avail. Edited January 21, 2022 by StickJock Quote Link to comment Share on other sites More sharing options...
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