From: Ethan Dicks (ethan.dicks_at_gmail.com)
Date: 2007-05-14 16:32:21
On 5/14/07, Mark Zablocki <firstname.lastname@example.org> wrote: > > Hi Ethan, > > I'm using new Athana 5.25 disks with the 8050. They should work fine. I don't know that brand. What are the published specs for it (coersitivity of the media, or at least the marketing "DSDD" or "DSHD" letters)? If these disks are for PCs, it would be nice to eliminate the media as a source of problems. > I found the following information in the 8050 Troubleshooting Guide at Zimmers.net: > > PROBLEM: drive appears to load but won't run. > > SOLUTION: check 6532s and UK3 controller ROM. > > PROBLEM: drive won't write/format. > > SOLUTION: check write protection tab in disk and switch on drive. > check write circuitry on analog board. > check write enable on digital board. > > > Unfortunately, I have no idea where these circuits are located or how to check them. I don't even know where to find parts. the 6532s are just that - 40 pin parts on the drive's main board with a part number of "6532" stenciled on the chip. The UK3 controller ROM is a ROM chip (24 or 28 pins) at the position marked "UK3". As for "write circuitry" and "write enable", you are going to need the schematics (zimmers.net?) and tools like a multimeter and/or an oscilloscope. A continuity tester might help with the write protection switch, but I think you would get an immediate error trying to format a disk with the write protect circuit "on". You would not get an immediate error if there were a fault in the write circuity on the analog board, but the format would still fail. You really should see if you can get a known-working 8050 disk to read-test. That would at least let you know that large portions of the drive are working. As for parts, well... ROMs can be re-burned with EPROMs and you can use pin adapters to use modern chips. replacing a 6532 is a little tougher. An analog fault on the analog board (bolted to one of the drives) should be easy to get parts for, once you determine what has failed. The only source I can imagine now for whole boards would be another 8050, since nobody has stocked spare boards for PET drives in a long time. > I appreciate any and all help. If you don't have component-level debugging tools, you are going to find it hard to diagnose component-level faults. Back in the day, a tech would put the drive on the bench, hook up a computer, issue some test commands (or run pre-fab C= diagnostic software) to make the drive read continuously, or write continuously, while poking at the boards with an oscilloscope. Eventually, that got too expensive, so they just swapped boards and sent dead boards back to a repair depot where a tech spent a few minutes on the board to see if it was easy to fix or not. Easy ones got fixed; hard ones got scrapped. There is no simple one-size-fits-all set of procedures to fix a disk drive - you have to start from what works and narrow down the search until you identify the specific part that's failed. When it's more than one part, the job is harder. Fortunately, in your case, you seem to be able to communicate with the IEEE CPU, so you can try to issue specific commands to the drive to see what works and what does not. If this were a 1541, the information is out there to tweak things at a very specific level (like being able to write specific bad tracks to replicate copy protection schemes), but, unfortunately, the same level of detail is not available for the PET drives as for the C-64. To sum up - try to find a known good disk. If it won't read, you'll have to look for the fault in a different place than if the drive reads but won't write. If you have to turn to someone on the list for a disk, try getting 2 - one to try reads, the other to try formats. See if you are having a media problem or a drive problem. All 5.25" disks are _not_ alike and _not_ interchangable. You have to match the media type for the drive model. It's not as simple as with 3.5" drives (where there are, essentially 3 types - commonly called "720K", "1.44MB", and "2.88MB", though those names are somewhat inaccurate from a technical standpoint). -ethan Message was sent through the cbm-hackers mailing list
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