stushug Posted February 11, 2023 Share Posted February 11, 2023 After posting my question about powering disk drives on or off with a disk inserted, I got to thinking about another issue. The XF551 has a drive busy light, but no power indicator. It seems like every time I use it, I forget to turn it off when I'm finished. When I come back to use it, it's slightly warm. While that in itself doesn't concern me, why did Atari chose to leave out a power indicator LED? One more LED on this unit couldn't have added that great amount to their build cost. I have a ton of LED's and it would be extremely easy to install one to show whether the drive is on or off. I'm just a bit reluctant to drill a hole in an otherwise unmolested drive. What do you guys think? Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 11, 2023 Share Posted February 11, 2023 the power led light can sit right next to the busy led light, it will shine through. No big thing and no holes drilled 2 Quote Link to comment Share on other sites More sharing options...
stushug Posted February 11, 2023 Author Share Posted February 11, 2023 47 minutes ago, _The Doctor__ said: the power led light can sit right next to the busy led light, it will shine through. No big thing and no holes drilled Suggestions like that are exactly why I posed my question here. What an elegant solution. Thanks, Doc! Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 11, 2023 Share Posted February 11, 2023 I wonder... There's an easy mod using a dual-color led and 2 NOT gates (one 74LS04 chip) according to the following diagram (IRQ == the "active" signal). What do you think about it? 2 Quote Link to comment Share on other sites More sharing options...
stushug Posted February 11, 2023 Author Share Posted February 11, 2023 3 hours ago, Peri Noid said: I wonder... There's an easy mod using a dual-color led and 2 NOT gates (one 74LS04 chip) according to the following diagram (IRQ == the "active" signal). What do you think about it? I really like that, and it seems very uncomplicated. I'll have to source some rectangle LED's, which also seems like a no-brainer. Quote Link to comment Share on other sites More sharing options...
stushug Posted February 17, 2023 Author Share Posted February 17, 2023 (edited) I received my bi-color LED's yesterday. Upon opening my drive this is what I found. I don't see any 74LS04 chips, only U3(74LS38N) and U4(74LS14N). Do I use U3 or U4? I'm assuming I have to remove the original LED, is that correct? Could I leave it installed and just bend the legs so it's out of the way? Should I solder the new LED into the original holes, then run a lead from the chip to the third leg for the red (what I'm using to indicate power on/off) LED? Also, which pin(s) trigger the busy light, #'s2+3 or #4? I showed a picture of the new LED simply sitting in the opening of the front bezel for reference. Edited February 17, 2023 by stushug Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 17, 2023 Share Posted February 17, 2023 You have to add this chip. It's not there. Quote Link to comment Share on other sites More sharing options...
stushug Posted February 17, 2023 Author Share Posted February 17, 2023 15 minutes ago, Peri Noid said: You have to add this chip. It's not there. Where do I get it, and where do I add it? Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 17, 2023 Share Posted February 17, 2023 (edited) It is a common chip, you can find it probably in any shop with standard chips. Look for 74LS04. There's no dedicated place for it an XF551 so you need to improvise - it needs power and ground and the activity signal. No one said it was a plug-and-play solution 😉 Edited February 17, 2023 by Peri Noid Quote Link to comment Share on other sites More sharing options...
stushug Posted February 18, 2023 Author Share Posted February 18, 2023 (edited) 3 hours ago, Peri Noid said: It is a common chip, you can find it probably in any shop with standard chips. Look for 74LS04. There's no dedicated place for it an XF551 so you need to improvise - it needs power and ground and the activity signal. No one said it was a plug-and-play solution 😉 I misunderstood at first, I thought it was plug & play. I guess I'll have to find a chip and go from there. I guess I can find power and ground, where do I get the activity signal? Edited February 18, 2023 by stushug 1 Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 18, 2023 Share Posted February 18, 2023 It's on the original led, of course 🙂 The resistors should be selected in such way that the light has levels matching your needs. By the way, this mod originally comes from C64, where they use it to show I/O activity. Quote Link to comment Share on other sites More sharing options...
BillC Posted February 18, 2023 Share Posted February 18, 2023 13 minutes ago, Peri Noid said: It's on the original led, of course 🙂 The resistors should be selected in such way that the light has levels matching your needs. By the way, this mod originally comes from C64, where they use it to show I/O activity. It should also be possible to simply reverse the operation of the BUSY LED, always on except when BUSY. 3 Quote Link to comment Share on other sites More sharing options...
stushug Posted February 18, 2023 Author Share Posted February 18, 2023 2 minutes ago, Peri Noid said: It's on the original led, of course 🙂 The resistors should be selected in such way that the light has levels matching your needs. By the way, this mod originally comes from C64, where they use it to show I/O activity. On the drawing you provided, the line labeled IRQ is supposed to connect pin 1 on the 7404 to the point where the original LED received the busy signal? I attached a picture with the pin circled. I assume I would remove the original LED, then run a lead from that point to pin 1 on the new chip. Is that correct. Please excuse me for asking so many questions. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 18, 2023 Share Posted February 18, 2023 (edited) not the first time a mod like this has been done for any number of computers, it doesn't come from any particular computer as it's been done on a multitude of disk drives including cumulus corp drives of decades gone by. BillC, I like your idea! That's a good minimalist move as well. Edited February 18, 2023 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 18, 2023 Share Posted February 18, 2023 1 hour ago, stushug said: On the drawing you provided, the line labeled IRQ is supposed to connect pin 1 on the 7404 to the point where the original LED received the busy signal? I attached a picture with the pin circled. I assume I would remove the original LED, then run a lead from that point to pin 1 on the new chip. Is that correct. I'd look there, yes. I don't know which lead it should be right now. I'd need to measure it. But I'm on vacation right now. Quote Link to comment Share on other sites More sharing options...
stushug Posted February 18, 2023 Author Share Posted February 18, 2023 19 minutes ago, Peri Noid said: I'd look there, yes. I don't know which lead it should be right now. I'd need to measure it. But I'm on vacation right now. Thanks. It will be a few days before I receive the chip any, so I'll wait to hear from you. Thank you for all the help so far. Quote Link to comment Share on other sites More sharing options...
stushug Posted February 20, 2023 Author Share Posted February 20, 2023 New problem here. The ribbon cable on the head broke, so I found another Mitsumi D503 on ebay and ordered it. I'll have to wait till I get the "new" mech to see if it all goes back together in working order. Is there a big difference between a Mitsumi D503 and a D503V? They're both 360k as far as I can tell. Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 20, 2023 Share Posted February 20, 2023 (edited) Both should work. By the way - I have a mech from an XF551 with exactly the same fault - a broken head ribbon. After I wasn't able to find a new one at a reasonable price, I replaced it with an Alps (after some modifications of the inside of the drive). And it works fine. Edited February 20, 2023 by Peri Noid Quote Link to comment Share on other sites More sharing options...
macsonny Posted February 21, 2023 Share Posted February 21, 2023 On 2/12/2023 at 3:44 AM, Peri Noid said: I wonder... There's an easy mod using a dual-color led and 2 NOT gates (one 74LS04 chip) according to the following diagram (IRQ == the "active" signal). What do you think about it? I love this solution. So elegant. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 21, 2023 Share Posted February 21, 2023 23 hours ago, Peri Noid said: Both should work. By the way - I have a mech from an XF551 with exactly the same fault - a broken head ribbon. After I wasn't able to find a new one at a reasonable price, I replaced it with an Alps (after some modifications of the inside of the drive). And it works fine. You should do a write up and let us know if it writes to an already initialized and formatted side second side of the disk Quote Link to comment Share on other sites More sharing options...
stushug Posted February 22, 2023 Author Share Posted February 22, 2023 On 2/20/2023 at 5:18 PM, Peri Noid said: Both should work. By the way - I have a mech from an XF551 with exactly the same fault - a broken head ribbon. After I wasn't able to find a new one at a reasonable price, I replaced it with an Alps (after some modifications of the inside of the drive). And it works fine. I've read a Chinon also works. Do you know the model numbers of the Alps you used, and which Chinon would work? Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 22, 2023 Share Posted February 22, 2023 I also heard that Chinons worked. But never met one in an original drive. I also don't have such PC drive to check how it fits in an XF551. I don't remember the actual Alps drive number I used, I can check it when I'm back home (in a week). I have some pictures though. The main problem with alternatives is their length - they simply do not fit. Any drive i know is longer than the original Mitsumi D503 by at least 1 cm, but it's usually 2 cm more. And they have the connector on the other side so the original ribbon is far too short. I had to replace the ribbon with a longer one, which was an easier part. I also had to remove a part of a radiator and replace original 7805 and 7812 regulators with something much smaller converters (Traco). Actually I could trim the radiator even more since now it's needed only for the rectifier (the converters need no cooling). Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 22, 2023 Share Posted February 22, 2023 11 hours ago, _The Doctor__ said: You should do a write up and let us know if it writes to an already initialized and formatted side second side of the disk Let me come back home. 1 Quote Link to comment Share on other sites More sharing options...
stushug Posted February 22, 2023 Author Share Posted February 22, 2023 I received my "new" mech today. Installed it into the case and all I get is a slowly occurring boot error message. The heads were filthy so I cleaned them and now they look brand new. The ebay mech was filthy and seemed suspect so I swapped the head unit into my old mech. While it was apart I cleaned and lubed the rails and sled. I also gave the heads another clean but I still have the same problem. I attached a video for reference. 20230222_153940.mp4 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 22, 2023 Share Posted February 22, 2023 You can't just swap heads without aligning them using a scope and alignment disk. You have now made your task next to impossible. 1 Quote Link to comment Share on other sites More sharing options...
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