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************ Topic 14 Sat Apr 10, 1993 R.KNOP1 [Rob Knop] (Forwarded) Sub: 1571 Disk Drives Generic hardware questions on the external 1571 drives. 116 message(s) total. ************ ------------ Category 4, Topic 14 Message 1 Sat Apr 10, 1993 R.KNOP1 [Rob Knop] (Forwarded) I've got this 1571 which is dead, and which blows any fuse which is put in the spot for the 125V 2A fuse in the power supply box. I've tried removing the power supply box (at the back of the drive) from the rest of the drive, and it still blows a fuse when I turn it on, so I believe the problem is localized to this power supply. Is there a "known" part which one expects to be the cause of such fuse blowing? If so, which one? Also, if it turns out to be one of the transformers (this would be my very uneducated guess), can anyone get me the specs on the two big transformers in this poer supply? (If not, what is the best way to go about figuring out which part in the poer supply is dead?) Thanks, -Rob ------------ Category 4, Topic 14 Message 2 Sat Apr 10, 1993 C128.JBEE (Forwarded) Those power supply things are over my head. Maybe a call to Earl Harvey would help :) ------------ Category 4, Topic 14 Message 3 Sun Apr 11, 1993 MIKE.DUNCAN (Forwarded) Rob, According to my notes, the next step is to check D101 (Bridge Rectifier), Q101 (Drive Transister), and Capacitors C101 thru C104. (Sorry. Don't have any data for the transformers.) Probably gonna be D101 or Q101. Send me E-Mail if I can be of any help. ------------ Category 4, Topic 14 Message 4 Mon Apr 12, 1993 HOWIE-CBM (Forwarded) Rob, I've always been told that power supplies are dangerous things to fool with. Wouldn't you be better off replacing the PS unit? On the other hand, if you can ID a bad part and replace it, this would be nice. JBEE's suggestion to contact Earl Harvey is a good one. If he cannot suggest a fix, he can probably supply you with a replacment supply. Howie ------------ Category 4, Topic 14 Message 5 Tue Apr 13, 1993 R.KNOP1 [Rob Knop] (Forwarded) Mike- Thanks for the info! The bridge rectifier is easy to check out with an ohmmeter, even not knowing which pin is what. Though I 'spect I'd have to take it out of the circuit anyway, in order to get a good test of it. (Pesky rest of circuit and all that.) The transistor is harder to test, but I guess a swap is a good a test as anything. Howie- yes, it is true that PS's can be dangerous to futz with. I think the primary reason is that they tend to have big momma capictors (or lots of 'em) which can store charge for some time. However, this one hasn't been plugged in in a few days, so I 'spect that it's pretty safe now. The problem with replacing it is, this being a 1571, the poer supply is another circuit board inside the 1571. I guess it's _possible_ this is a standard PS circuit board, since on the side it sais "Model SR23 Mitsumi Elec. Co. Ltd.", but I am not too hopeful that I'd actually be able to order another one of those. Perhaps Earl Harvey would have a replacement, but in any event it would be some number of tens of dollars to fix. On the other hand, if I can get away with replacing one or two components, it'll only run me a few bucks. -Rob ------------ Category 4, Topic 14 Message 6 Sat Jul 31, 1993 J.BROWN122 at 19:10 EDT Heres a question for the powers that be. I have 1571 where the second drive head has gone bad, ie it act like a perfectly good 1541 now. I can get the drive to replace the old one 5 1/4 ld but i was told that the plug connection had to be wired differnetly to work with 1571 "brain" so who knows ??? ------------ Category 4, Topic 14 Message 7 Sat Jul 31, 1993 C128.JBEE at 23:26 EDT The 1541/71 drives are wired differently because they are very different and not interchangable. ------------ Category 4, Topic 14 Message 8 Sun Aug 01, 1993 CBM-ED [e.g.bell] at 09:46 EDT If it is a 1571 compatible drive unit you got, and need to know how to rewire it, then perhaps, John, Tc128/64 may be of some help in an upcoming issue? ------------ Category 4, Topic 14 Message 9 Sun Aug 01, 1993 J.BROWN122 at 15:17 EDT the problem is that I need to know the info now. Because I am down to 1 1571 and it starting to act funny. I am ruishing like mad to save all my files to a 1581, before my last 1571 dies. I can't afford a shop repair at $170 dollars.... ------------ Category 4, Topic 14 Message 10 Mon Aug 02, 1993 C128.JBEE at 00:30 EDT I keep harping on this one point, but CLEAN the drive before suspecting that it is going bad. Use a cleaner disk but also see if you can't clean it with a swab. The cheaper disks will leave a coating on your drive heads and make it act like it is going bad. The early external versions of the 1571s are usually pretty reliable. Most of the defective 1571s are the CR1571s found in C-128Ds. ------------ Category 4, Topic 14 Message 11 Mon Aug 02, 1993 J.BROWN122 at 00:35 EDT It's been cleaned by a Commodore Repair person, and it only formats in the 1541 mode. When you try to format the disk double sided it prints a disk error and refuses to go any further. ------------ Category 4, Topic 14 Message 12 Mon Aug 02, 1993 CBM-ED [e.g.bell] at 01:10 EDT John is right. I said the same thing and did a good cleaning and it worked ok. Previously had spent $150 to replace the mechanism for the same problem. On the fair side, the cleaning I finally did was involved and I was scared... just figured I had nothing to lose at that point and took a chance. But a cleaning disk did not cut it. I disassembled the drive and heads, and worried the whole time. But you may need a whole new mechanism, which is an expensive repair. Very expensive. ------------ Category 4, Topic 14 Message 13 Mon Aug 02, 1993 F.OGLE [Color BBS] at 19:30 EDT I have a local user who aligned my half-dead '71 (cracked top head), and he replaced it, supposedly with one from a third-party drive (not sure who or what it was used with), but I will ask him to be specific in what he did, and I'll get back to you (my 1571 works like a little baby now :]) Fred ------------ Category 4, Topic 14 Message 14 Tue Aug 03, 1993 D.PFAFF [Beowulf] at 22:33 EDT The internal 1571 on f my 128D died a while back, and I found that the upper head mount had broken. Co Certified Commodore epair personnel would only quote me the price of replacing the f dric ve mechanism, not just the ha ead anf d /or it's mount, all for $125.00 it's mount, all for the price of $125.00. So, I did the nest c xt best thing, and and went out and bought a used external 1571. I took the mechanism from it and installed it inside my 128D, adding the JiffyDos ROM while I had the 128S D opened up. Worked great, and only after I did that s did a nother C= repairman warn me that the 128D's internal 1571s were failure prone. Aargh! ------------ Category 4, Topic 14 Message 16 Wed Aug 04, 1993 CBM-MARK at 22:55 EDT With my original 1571 it was the hold-down spring for the top head that was weak. had all kinds of problems formatting and saving to disk until I took the spring out and stretched it some. Been working perfectly ever since! ~~Mark~~ ------------ Category 4, Topic 14 Message 17 Mon Aug 09, 1993 D.TUOMI [Doctor] at 03:59 EDT My 1571's have been acting peculiar too. It's not particularly easy to diagnose problems with them. For example, on one of mine I had it to start acting funny, but a good cleaning solved the problem, while on another drive it was behaving more like a 41than a 71 and nothing short of a trip to the repair shop would replace it. I wish that Commodore had used standard mechanisms in its devices so that they could be simply swapped out. I cannot currently afford the rather excessive amounts that are charged by the typical Commodore Certified Repair Technician. Doc. ------------ Category 4, Topic 14 Message 18 Wed Aug 11, 1993 AMFORD at 22:42 EDT A simple test to see if you actually need to bend the spring on the top head of the 1571 is to place a penny or two on top of the head. This will add a bit of pressure. Then try formatting the diskette. If it formats, the spring needs to be bent. If it doesn't format, well... you were saving up for the repair bill weren't you? :) ------------ Category 4, Topic 14 Message 19 Sun Aug 15, 1993 P.KELLER5 [Diesel II] at 09:46 EDT Gee, all these problems with the internal 71's! I have had my 128D for 2 years now with no problems, so far (did get a device switch put in)! Also, had a user group club member put The Servant on a chip, which keeps the internal 71 drive from whirring everytime you turn on the computer, another big plus! So that's my story! ------------ Category 4, Topic 14 Message 21 Sun Aug 15, 1993 M.NEUS [Neusoft] at 23:44 EDT I have a 128D for several years now...but I went through several up front, usually from the drive. Anyhow, I finally got one that works, and its been going strong for 6 years now. $170 to repair a 1571???? Either get yourself a new repair man, or prehaps even better, used, working 1571's are easilly found for under $100, $70 or so being typical. Mike ------------ Category 4, Topic 14 Message 22 Mon Sep 06, 1993 P.KELLER5 [Diesel II] at 07:20 EDT Yeah, I had my internal 71 relubed as well. But with The Servant on a chip in my 128D, at least when I turn on the computer the drive dosen't automatically whirr and click. Now waiting on JiffyDOS! ------------ Category 4, Topic 14 Message 23 Fri Nov 05, 1993 I.MCKINNEY [TheBigMac] at 02:19 EST I have a 128 with a 1571 and 1581 drives. When I turn on the computer, either in 64 or 128 mode, the 1571 fails to initialize occasionally. A friend in my local users group said that a chip in my drive was on its way out. If this is true, which one is it? Or what is truly the problem? ------------ Category 4, Topic 14 Message 24 Fri Nov 05, 1993 C128.JBEE at 07:47 EST If it resets when you press the RESET key, then I just think it is a case of the bus getting hung because of timing differences. ------------ Category 4, Topic 14 Message 25 Sun Nov 07, 1993 D.TUOMI [Doctor] at 16:14 EST It might be your serial cable. I had a friend who had a serial cable with an intermittant signal problem. Once he replaced his cable, his 1571 would come up correctly. Doc. -please excuse my spelling, I know it's really bad... ------------ Category 4, Topic 14 Message 26 Tue Nov 09, 1993 I.MCKINNEY [TheBigMac] at 02:17 EST I have used 3 different serial cables and they did not fix my problem. When I hit RESET it occasionally will reinitialize and sometimes it won't. It does appear to be something in the drive to me. I have hooked up a friend's 1571 and it works perfectly. Too bad she won't sell it to me. I know the Grapevine Group sells the chip I need but I need to know which one I require. Any help or other advice will be greatly appreciated. ------------ Category 4, Topic 14 Message 27 Tue Nov 09, 1993 H.HERMAN1 at 04:12 EST BigMac, You might try a Head Cleaning Disk Kit, in case a tiny piece of lint is causing what you describe. ( am pretty certain there is a disk spinning program in the Library that you can use with it. If you do not find it, let me know, and I can upload one.) If this does not work, then opening the drive, and *carefully* cleaning the heads with a cotton swab and alcohol is another alternative. While you are cleaning things in any event, I would also recommend cleaning all the serial port contacts. Accumulations of corrosion can wreck havoc. Howie ------------ Category 4, Topic 14 Message 28 Fri Nov 12, 1993 I.MCKINNEY [TheBigMac] at 00:58 EST To: H.HERMAN1, Thanks for the advice. I'll try it. It has been a while since the head has been cleaned but I don't really think it has anything to do with the initialization problem I have. I did switch the serial and interface connections on my 1581 drive and the 1571 seems to initialize more often now, but it still hangs up from time to time. BTW, I don't think the corrosion theory will wash for me. I live in Tucson, Arizona and it is drier than hell on a summer's day here. ------------ Category 4, Topic 14 Message 29 Fri Nov 12, 1993 C128.JBEE at 03:21 EST If you have access to two 1571s, I would say try swapping the 6526 (or is it 6522?) chips in the 1571s. I would use a chip puller though and not rely on a screw driver. You could also try swapping the drive assembly since that is pretty easy. I have never replaced a bad rom in a 1571, so I would try that last. ------------ Category 4, Topic 14 Message 30 Sat Nov 13, 1993 I.MCKINNEY [TheBigMac] at 01:46 EST I'll try it when I can get my hands on the drive. I'll keep you posted. ------------ Category 4, Topic 14 Message 31 Sat Nov 20, 1993 I.MCKINNEY [TheBigMac] at 17:59 EST I think I found my problem. I was doing a 128 demonstration for a TV station here in Tucson, AZ and while I was checking out my equipment my computer kept flickering on and off. After it warmed up it seemed to work fine. I have noticed this flicker at home sometimes, but it wasn't enough to toggle my 128 off and on like it did at the station. I guess it looks like the power supply is on its way out. Any other ideas or suggestions would be appreciated. ------------ Category 4, Topic 14 Message 32 Sat Nov 20, 1993 C128.JBEE at 23:19 EST Yes, if you have a flat C-128, make sure that the power connector is plugged firmly into the computer. Also, the switch itself on some flat 128s can go. I would check my power supply with a meter and if met the +/- 10% of the rating on the back of the power supply I would look for simple causes, like a bad video cable. ------------ Category 4, Topic 14 Message 33 Fri Dec 17, 1993 R.PATERNOST2 [Ray] at 01:06 EST This is for the person who was having trouble with the power supply circuit board in his 1571: If everything else has failed, and the drive in still in the same condition it was in since April (I know I'm jumping in realy late on this), I would suggest obtaining a PC power supply (preferably a small one!), and wiring the connector from the 1571 power supply onto the correct points off the PC supply. The 1571 board uses +5V and +12V, which appears to be rather common in the electronics world. Actually, the supply doesn't have to be as big as one for a PC computer; as long as it puts out both voltages rated at about 1A, you're safe. One vendor that I've ordered from many times has a few supplies for under $20. The down side is that the supply will probably have to be outside of the 1571 case...... ------------ Category 4, Topic 14 Message 34 Sat Apr 23, 1994 R.KIRK7 [Dick] at 19:21 EDT I tried to load what appears to have been a bad disk as I got this terrible screeching sound. Now I caint load any disk directory or program. My alignment program indicates ok on half tracks and out of alignment on every track. Anyone else had any alignment problems with a 1571? ------------ Category 4, Topic 14 Message 35 Mon Apr 25, 1994 C128.JBEE at 19:32 EDT Open up the disk drive case and make sure the heads are clean and that a loose write protect tab has not lodged somewhere within the drive assembly. The screeching sound could have been from dirt on the disk, which means at least a good cleaning. ------------ Category 4, Topic 14 Message 36 Tue Apr 26, 1994 R.KIRK7 [Dick] at 22:18 EDT The bad drive did turn out to be a dirty head. The victum of a disk I had just purchased at a garage sell. The drive is back to normal operation. Hope it wasn't damaged any. the disk has a nice groove in it. Don't think I will try it anymore. Thanks for the suggestion. ------------ Category 4, Topic 14 Message 37 Sun May 01, 1994 L.SCHONDER [C128.LOU] at 12:14 EDT On the 1571 alignment issue: From what I understand, the '71 is not mechanically alignable like the 1541. Alignment is performed eletronically. PLEASE CORRECT ME if I'm wrong! :D ------------ Category 4, Topic 14 Message 38 Sun May 01, 1994 B.MASSE at 19:22 EDT L.SCHONDER [C128.LOU] says.... On the 1571 alignment issue: From what I understand, the '71 is not mechanically alignable like the 1541. Alignment is performed eletronically. Bob says... gee let me correct you then... I think that the 1571 electronic sensors will keep the 0 track stop in check.... But alignment is just about the same as with the 1541 (although a heck of alot easier). I believe that the 1581 zero alignment problems but I don't know for sure about that one... Bob ------------ Category 4, Topic 14 Message 39 Mon May 02, 1994 L.SCHONDER [C128.LOU] at 23:45 EDT Well ... uh ... I wAs close! ;D ------------ Category 4, Topic 14 Message 40 Thu Jul 07, 1994 S.EYRSE [steve] at 01:09 EDT How do you tell the '71 to act like a '41 and just read one side? I don't have a book and the '71 is in a D I just got. Seems I read somewhere about sending code so it would work either way. The manual that came with the D hasn't anything on this. OR if I put a '41 disk in will it read both sides with out "flipping it". Backwards rotation? Thanks Steve: ------------ 4 |