Supradrive 500xp Repair

[nick3092]

I recently acquired a Supradrive 500xp that appeared mostly dead and got it working again. Figured I'd post the details here incase they help someone else.

 

The symptoms were the unit powered up, but the busy light never showed any activity. The drive spin up, but the supraboot tools would report that no controller was found. The extra memory was not visible either.

 

I noticed if the drive was not installed (leaving the bus/chain unterminated), the busy light came on steady. That gave me hope the SCSI controller was at least acting sane. I then used my Chip Tester Pro to dump the bios. The resulting file checksum seemed to match what UAEwin had in the source code for my version of the bios (AMAB5). That gave me confidence the bios was good. I tested the 4 ram chips with my CTP, and all 4 came back as failed. But I wasn't convinced they were bad.

 

The unit has multiple DIP ICs - SCSI controller, bios, 4 custom PAL chips, and 8 74xxx logic ICs in the top. On the bottom are 6 SMD logic chips. With no way to test the PALs due to the unknown custom programming, out of desperation I began testing the DIP logic chips. Unfortunately none were socketed, so I pulled out my desoldering gun and went to work (with some help of low temp solder). After removing and testing each chip, I installed a socket and replaced the IC. All tested good until I reached the last one - 74F32. It failed consistently on my CTP. Just in case my CTP was giving any false passes, I ordered a full set of logic chips from Digikey.

 

Before the ICs arrived, my BlueSCSSI v2 internal arrived. I used the initiator mode to connect up to the 52MB Quantum drive. After the drive spin up and some fast led blinking on the BS (and the occasional drive head noise), the drive spun down and the led blinked slowly. Disconnected everything and checked the SD card. Sure enough, a 52MB file was written out. Looked at it with a hex editor and saw some things that gave me hope (like partition names of DH0 and DH1, some occasional plain text, etc). So the drive seems fully functional. 

 

Then a day or two later the ICs showed up. I replaced just the 74F32, and hooked everything back up. This time I started seeing flashes off of the busy LED and supraboot was able to identify the Quantum drive. I then rebooted with no floppy and the system auto booted the hard drive into a working copy of workbench.

 

Workbench could see the memory now, but I wanted to make sure it was in fact good. So I booted up a copy of Amitest and let it run for a while. After 30-some passes, I decided the memory chips were good, and CTP was giving me a false positive.

 

Confident everything was good, I removed the quantum and installed the BSv2. I put a blank 100mb image on the SD card (not sure what the upper drive limit is, but I think I read some where the v6 of the bios increases the max size that my v5 bios will accept) and didn't set any options in the BlueSCSI.ini file. Fired up Supraboot and it detected my virtual drive. It went through the partitioning and formatting and then offered to install workbench for me. Let it do its thing, then rebooted to the "hard drive" and had a nice fresh WB install with lots of room.

 

Hopefully walking through my scenario will help someone else with a malfunctioning 500xp. And also good to know BSv2 "just works" with the Supradrive if anyone was considering it. 

Edited February 15 by nick3092

[nick3092]

I forgot to mention that you can run a SD card extender out the Supradrive's side car cover, and I used some removable double side tape to stick it to the top for easy access to the BS card. The ribbon has a sharp bend on it, but still works. Time will tell if the sharp bend has any negative impact. If you leave the sidecar cover off, you wouldn't have to have such a sharp bend. 

 

 

[+OLD CS1]

Nicely done.  Thanks for the post.  I never had one of these, rather then GVP series units which have all been great and, thankfully, never suffered a failure.  But, time is not our friend with our beloved machines.