Commodore.ca: The PET, VIC, 128, 64 & More Forum

Just got an SX-64 off Ebay. It's got issues. It has a problem keeping a horizontal hold, the disk drive runs continuously with the light on steady. Oh, and it didn't have a keyboard cable. I fixed that by getting a DB25 male to male cable from Radio Shack for 10 bucks. Had to modify the plastic to make it fit into the chassis, but it works real nice. I basically used Commodores exclusively in the early eighties, bought my own C-64 with my paper route money! Always wanted an SX-64, nothing looked cooler back in the day.
I actually removed the rom for the drive and powered it up, it still spun and the light stayed on, don't think it's the rom. I even swapped the 6502 with one from an older Apple II+ (probably not a great idea) to no avail. There were two pins on one of the 6522 that weren't even in the socket, I corrected this, but still the same issue. If anyone has any ideas, I sure would appreciate the help!!

Well I cant help you, but I can send you to the website of the repair person I used to fix my SX-64.

http://personalpages.tds.net/~rcarlsen/

He does have a few articles there to help people repair thier own stuff.

If you cant find what you need, try emailing him, he is a nice guy and may help you.

moparram wrote:I even swapped the 6502 with one from an older Apple II+ (probably not a great idea) to no avail.

No, not a great idea as the SX-64 did NOT use a 6502. It used a 6510 and as subtle as the differences are, they're important.

I swapped the 6502 processor on the FDD controller board, I didn't touch the 6510 on the CPU card. I'm thinking one (or two) of the logic ICs on the controller are bad. It couldn't hurt to replace them all.

moparram wrote:It has a problem keeping a horizontal hold, the disk drive runs continuously with the light on steady.

Though I cannot help you with the horizontal hold problem, the disk drive problem is a different matter. I've had many SX-64's repaired by Ray Carlsen, and the drive problem was always related either to the 6526 chips or the PLA chip.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

The horizontal hold/adjustment should be fairly easy to adjust on your own
with a screw driver. Infact, they trimmers are all accessible and labelled.

Once you get your drive working properly, there is a mod you can do to
the reset circuit to give it a dual purpose:

http://sdf.lonestar.org/curiosity/sx64

Good luck with it!

I think I basically need to score one (or two!) 1541 drives for parts. I tried removing all the socketed chips and reinstalled them. I think I can rule out the FDD controller board's 6502, the I/O board's 6526 because the keyboard works fine (unless only the lines referencing the floppy are bad!). Back in the day, I had a bunch of Commodore stuff, it was ridiculous. I could sure use some now! My dad even got a bunch of 1540 drives cheap (about 22-23 years ago) and he updated the ROMs to work with the C-64. I always had a joyus time adjusting my drive's stepper motor, trying to get that "sweet" spot! I wish this SX-64 were that easy.
I think this SX-64 doesn't like being in my basement (alittle chilly?), until it warms up that old CRT!

The SX-64s fetch a good price on eBay, even the broken ones.

It is probably the one you should keep best care of because it is getting harder and harder to find them.

Keep it in the bottom of your closet, not your basement.