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Pet Disk or IEEE-488 Issue

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Nicolas

Member
Joined
Jul 9, 2013
Messages
26
Location
Nicosia - CYPRUS
Following the ressurection of my 8032 pet earlier this week, after some video RAM problems, I have tried to connect my PetDisk to load some programmes from my library.

I have connected the machine up, see photo 1, configured as device no 9, as per Bit-fixer's instructions (jumper on right 2 pins), but was not able to do any retreiving from my saved programmes (double checked my 2GB SD card on my regular desktop and programmes are there, written on card).

Was not able to look at the directory, save or retrieve any files either.

Maybe I was doing something wrong? (see photo 2) else how shall I start troubleshooting? Would the problem be with the PetDisk or the 6520 (UB16)? Or maybe I am tyring something wrong?

Any ideas please as to how to tackle this problem? Have tried also other jumper settings on the PetDisk, tried changing device number to 8 or 11 but no luck.

Thanks, Nicolas IMG_0788.jpgIMG_0791.jpg
 
Hi Nicolas,

I randomly started having trouble with my Pet Disk where my 8032 would freeze whenever I tried to load anything. I could read the data from the SD card on my PC without issues. I finally managed to get it working again by backing up all my files then reformatting the SD card. That's the only time I've ever had trouble with the Pet Disk.

Good luck!

Heather
 
Hi Nicolas, the only way I had problems was if my 4040 was attached to the IEEE bus and was off. The PetDisk is almost bulletproof. Simply power off, remove connectors and carefully reconnect taking care with alignment of pins. If no go, do as Heather suggests.
 
Thank you both. Will try reformatting the SD card tomorrow and let you know how it goes. i have powered off, removed and reconnected petdisk several times without luck...
 
Just for the heck of it I'd try cleaning the card edge connector on the back of the motherboard with some alcohol. Contact oxidation is problem with those machines.
 
i have cleaned the contacts of the edge connector, reformatted my 2GB Micro SD card, but still i get exactly the same response as on my 1st post photo.... it is as if the petdisk is not seen. Could be some issue with IEEE interface circuitry.... I will persue what jltursan has suggested....
 
I just got the idea of removing, bending all pins of 6520 (UB 16) a little bit outwards and resitting the chip. That did the trick.....petdisk working once more.....apparently I had a bad contact somewhrere on one of 6520's pins. I hate the idea that I now might need to replace this 40 pin socket pretty soon, should I get this problem again....

thanks to everybody for all their help....

Nicolas
 
Ditto on the "great job" finding that. I wonder if I might have a similar problem with the spare Dynamic PET board that is perpetually on my list to finish repairing. (I'd gotten the main bits to mostly work but found a replacement board before I made much progress with the IEEE port.)

My TRS-80 Model I likewise has an iffy 40 pin socket in the Expansion Interface where the floppy controller IC plugs in; there's a "doubler" board plugged into it and I typically have to reach inside the I/E with my pinky and give it a wiggle to get the disks working again whenever the system is moved. I should replace it with a good machine-pin socket but I'm sort of loathe to solder on it unless I absolutely have to.
 
is there an effective way of removing these sockets? you need to hold the soldering iron with one hand, the vacuum operated pump on the other hand to press once solder melts at each pin, then you need another hand to exercise some pressure on the socket pulling it out (or to the individual socket pin to get it out of its socket)..... you need at least 3 hands and the pet board supported vertically somehow..... unless you have 2 people on the job, then you run out of hands, or if you tri it alone is a nightmare.... is there something out that I am missing out or doing wrong?
 
Nice job recovering the PET!, these damn PET sockets are always giving headaches...

Desolder a socket is a bit harder than an ordinary IC. You can't use (or at least is a dirty task) an air desoldering station and must use a soldering iron and a vacuum pump.

About desoldering tricks, I usually follow these guidelines :

1) "Refresh" the old tin with new one. Add only a little bit...
2) While applying the new tin, try to straightent the pins. An slightly bent pin could be a lot harder to desolder.
3) Add some flux to each pin row.
4) If your soldering station has a temperature control, raise it a bit.
5) If after your first try there's still tin in the hole, resolder it again with new tin and repeat.
6) Try to keep the pump as clean as possible.

Good luck!
 
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