Keneg

When my Ingot supplies failed, they provided 5v until the computer was turned on and then dropped to about 3v. So it might just be a weak supply, not the computer drawing too much. I got different symptoms on my 600 XL and 800 XL, but both now work with supplies I built.

I was using MyDOS 4.50 because it comes with the RespeQt software. I downloaded 4.55 beta 4. I like it so far. Was able to create DD disk and copy DOS files to it. It then booted fine. Thanks for pointing it out to me.

Check the resistance of the plug wires. LOL

You may try it again after it cools off. It sounds like it may be a component overheating. Also, if it is truely killing power adapters, that is most likely something shorted. I just repaired a 1050 drive that turned out to be a leaking capacitor. It finally burned up. As suggested above. Use a multimeter to test the output of the power supply. First with the computer off and then with it turned on. Report the results here and we can go from there. Your symptom does sound similar to what I got when the power supply on my 800 XL failed.

I believe there are some later versions of DOS 2.X that added DD support. 2.6 and 2.8. Also there is HappyDOS, but imdon’t See much about it, so I assume there are reasons it isn’t used much.

I used SpartaDOS 3.2G last night to verify that double density works, but I don’t think it is compatible with DOS 2.X. I found a list of Atari DOSes that gives a few comments on each. It would be nice to have a list of them that work well with the Happy enhancement and are DOS 2.X compatible. Is MyDOS 4.55 compatible? How important is compatibility?

I’m not sure which version of MyDOS I have. When I typed P and then 1,D I got 1H on the top of the screen. Formatting a new disk gave me 0568 sectors. Very strange. If the sectors are 256 bytes, that would be 142k. I used the Happy disk to copy a 180k disk from my SIO2PC-USB. That seemed to work. There was something about adding a file to a DOS 2.5 disk and naming it autoexec.???. I will have to read more and experiment with it.

OK, I thought I tried MyDOS. I will look at it again.

I installed it tonight. Ran the Happy diagnostics disk and tested good. Yes, I can tell it’s much faster. Now how do I use the true double density mode, especially format a double density disk?

Replaced C21 tonight and the drive still works. Next will be to install the Happy 1050. I want to see how much faster it will be.

I didn’t have time to test the drive last night after clipping one leg of C21. Tonight I hooked back up the drive mechanism and turned it on. The head moved normally. I turned it off and moved it to one extreme or the other and turned it back on a couple of times. It always moved to the correct position. At this point I am getting somewhat excited. Next I inserted a blank diskette. The activity light came on and the disk spun! WOW! So then I boote my 130XE to DOS2.5 and switched to this drive. I formatted The disk, transferred DOS files, and was then able to boot from it. I then switched back to my other 1050 and was able to,boot off the same disk. So, once I receive and install a replacement C21, it is fixed. I am considering ordering and installing a Happy adapter for it. Thanks to all who helped here. Once I have this one finished, I will have to tackle the World Storage drive again.

@1050 ... thanks for the advice. I did cut one leg of C21, but havent turned it on since. One thing I noticed is that the connector to the stepper motor is plugged in backwards to the rest. It is J13 I think. I can see the numbers of the other 3 and they line up. That one sticks out and I think the number is towards the heat sink.

While trying to read voltages on the Tandon drive smoke started rolling. Not sure if my probe shorted something or the component just finally failed. I was trying to read voltage at Q6 and may have contacted TP12. Tonight I took it apart and found C21 burnt to a crisp. It is a 4.7μF 16 V capacitor according to the schematic. The strange thing is that when I tried the drive once everything cooled down, the head tried to move. It had never budged before. There is a 100μH inductor next to it that is discolored, but I think that is just from the capacitor. So should I just buy another capacitor, change, and try it or should I do more checking first?

OK, that is a good suggestion. I will do something like that if I can’t fix the issues. That might be a good temporary fix to see if the rest of the drive is working before investing too much time and money into it.

Yes, and I have downloaded the service manual so I know what voltages I should see. I need to get a fuse for my multimeter before I can continue.

OK, the consensus seems to be to fix it rather than modify it. Can anyone provide a step by step guide to troubleshooting? I am thinking to start by testing*p the diodes and capacitors until I get the correct voltages input to,the voltage regulators. Then if a regulator is bad, use the newer part to decrease heat.

OK, it was just an idea. I dont really consider it hacking up the drive because it could all easily be put back to stock later. What about using a PC supply with the power good pin jumpered as a troubleshooting device? Has that been done? If so, do you have to disconnect the 7805 and 7812 or can you use alligator clips to TP 13, 14, and 15? I am thinking that getting power at these points would let me determine if the power circuit is the only problem or if there are more issues.

Thanks for the link. That seems to still use much of the power circuit components. My idea was to get rid of most of the diodes and capacitors that fail. I have two drives imam working on that seem to draw too much power. I think the 12 volt side is where the problem resides on at least one of them. This modification would eliminate that entirely.

I am hoping the difference between 9 an 12 volts to the 7805 is within its operating limits. I thought about using a PC power supply and I do have a spare, but I was looking for a more compact solution. Thanks for your input. Edit: I just looked at the data sheet. I should have done that before posting. The input voltage range is 7.0 to 35, so I think that wont be an issue.

Proposed Atari 1050 power supply modifications Supply 12VDC to the Power jack. (2 or 3 amps) Remove CR15-20. Remover Q8. Put jumper wires were CR18 and CR20 were. Put jumper wire between where CR15 was and where output of Q8 was. If the 12VDC supply is clean enough, C67 could also be eliminated. I am not at all expert in electronics, so please share any thoughts you have, especially problems this may cause. I realize some people might want to leave their 1050s stock, but I just want mine to work as reliably as possible. I think the voltage doubler and some of the other circuitry this would bypass increase the current draw and are sources of problems. I would put a label by the power jack noting the change. The power circuit diagram didn't paste in. I have attached the image file below.

The drive I have been working on is a World Storage. I don’t see any obviously bad caps. I am thinking I should start with the large electrolytics? I also just got a Tandon 1050 with even worse symptoms. It doesn’t do anything except light the power light when turned on. The voltages I checked were very low or nothing at all. The head wouldn’t move at all, but some sewing machine oil on the shaft of the stepper motor and moving it back and forth seems to have freed it up. The electrolytics on the Tandon are 2x6800uF 35 volt and one 4700uF 25 volt 85C. The World Storage has 3x4700uF 35 volt electrolytics. So, is this a good place to start?

Ok, thanks for the info. I will try to do some more checks tomorrow. While I haven’t looked closely, I haven’t noticed anything that looks burnt. I will use a light and look closer.

Got in my 3086 chips and replaced the two I found. No change in the symptoms. I checked some voltages. At the power switch I get 10.18 VDC when off, but only about 5 VDC when turned on. I checked voltages at the regulators and got 12, 5, and 2 VDC. TP13 had around 5 while I had nothing at TP15. I need to get some mini clip on leads. It scares me trying to read voltages with my leads. Afraid I will short something out.

I got both my working 130XE and 1050 as untested. I just make sure that I get them cheap enough to make it worth while. My 800XL just had a bad power supply and my 600XL I was able to repair the keyboard. Good deals and I enjoyed learning how to fix them with a lot of help from this forum. I am amused sometimes when the listing is for the computer, PSU, and cables but listed as unable to test. Are these sellers really that clueless and/or lazy. A few minutes to hook up and show a picture of it working would probably double the price.

If I rad that thread correctly, at least part of the problem was a bad 3086 chip. I have 5 of them ordered. They arrived at USPS in Chicago from China on the 25th.