jms@vanth.UUCP (Jim Shaffer) (01/22/91)
A few weeks ago I posted a request for help with a problem with my A500. It was locking up occasionally when I tried to use the floppy drives. I got three suggestions from the net: First, that it was a bug in trackdisk.device. Second, that it was a power supply problem. Third, that it was a bad 8520 chip. The first suggestion didn't seem to be relevant because I was using both SetPatch 1.3.2 and Tracksalve, both of which are supposed to take care of that bug. Furthermore, the problem gets much worse when the system has been on for a while and has heated up. Keeping a fan running to cool the system helps a lot. The second suggestion also didn't seem relevant, because the fan was blowing on the system rather than on the power supply. The third suggestion, a damaged 8520 chip, was also suggested to me by several people I talked to in person, including some who have had to replace several 8520s in the past. So I replaced both my 8520 chips. Unfortunately, replacing the 8520 chips had absolutely no effect on the problem. I'm now looking for other suggestions. Although the fan prevents the problem almost always, the noise of it is starting to annoy me. Also, the fan causes the image on my monitor to waver slightly. The waver is accompanied by a minor color shift. It's tolerable, but I don't know if it's safe for the monitor. (It's a 1084S, if anyone wants to speculate.) Worse, I doubt that the fan will be adequate in the summer. Does anyone know what the next step should be? To repeat the problem, my A500 locks up totally when I try to use the floppy drives after the system has been running for about an hour. (When it's cool, it's fine.) The problem happens most often when something is using DF1: and I try to invoke a new command from DF0:. As soon as the DF0: motor comes on the system locks up. (Both drive motors stay on.) I've also had the problem happen rarely when accessing just one drive after a period of inactivity, but it happens most often when I try to use both drives at once. I've had it happen when I'm trying to WRITE to DF0: also, and the files remain untouched -- it definitely seems to happen as soon as the motor comes on. -- From the disk of: | jms@vanth.uucp | "Glittering prizes and Jim Shaffer, Jr. | amix.commodore.com!vanth!jms | endless compromises 37 Brook Street | 72750.2335@compuserve.com | shatter the illusion of Montgomery, PA 17752 | (CompuServe as a last resort)| integrity!" (Rush)
jesup@cbmvax.commodore.com (Randell Jesup) (01/24/91)
In article <jms.2412@vanth.UUCP> jms@vanth.UUCP (Jim Shaffer) writes: >It was locking up occasionally when I tried to use the floppy drives. I >got three suggestions from the net: First, that it was a bug in >trackdisk.device. Second, that it was a power supply problem. Third, that >it was a bad 8520 chip. >Unfortunately, replacing the 8520 chips had absolutely no effect on the >problem. I'm now looking for other suggestions. >the fan causes the image on my monitor to waver slightly. The waver is >accompanied by a minor color shift. Sounds a lot like a hardware problem, likely a PS voltage problem. It also could perhaps be input power problems (low voltage or spikes or some such), though this seems less likely. Note: I'm a software guy, not hardware. -- Randell Jesup, Keeper of AmigaDos, Commodore Engineering. {uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com BIX: rjesup The compiler runs Like a swift-flowing river I wait in silence. (From "The Zen of Programming") ;-)
abrown@hpcvca.CV.HP.COM (Allen Brown) (01/25/91)
> Furthermore, the problem gets much worse when the system has been on > for a while and has heated up. Keeping a fan running to cool the > system helps a lot. The second suggestion also didn't seem relevant, > because the fan was blowing on the system rather than on the power > supply. That doesn't eliminate the power supply. You have stirred up the air all around the system. The power supply benefits along with the rest of the system. And the fact that starting up the floppy triggers it strongly suggests that the power supply is involved, since that involves a surge of power. > Does anyone know what the next step should be? To repeat the problem, > my A500 locks up totally when I try to use the floppy drives after the > system has been running for about an hour. (When it's cool, it's > fine.) > -- > Jim Shaffer, Jr. | amix.commodore.com!vanth!jms | endless compromises Depends on how adventurous you are. I think that you have demonstrated that the problem is temperature related. So the next step is determining what device(s) are vulnerable. If this was a TV, you could wait until it fails and then use a spray coolant to find what needs to be cooled to make it work again. That probably won't work with a computer. So you could use the opposite approach. Use a heat gun (such as a hair dryer) to heat sections of your computer. When you heat the weak part the system should fail pretty quickly. Now a hair dryer is very poor at directionality. So once you have isolated the problem to perhaps a tenth of the system you can do the same test again with a soldering iron on individual components. #define DISCLAIMER The procedure described above may be capable of damaging your system. Use at your own risk. If you don't know what you are doing, pay a professional to fix it. -- Allen Brown abrown@cv.hp.com or abrown%hpcvca@hplabs.hp.com or hplabs!hpcvca!abrown or "Hey you!" Not representing my employer. If a thing is worth doing, it is worth doing badly. ---G. K. Chesterton