Disk Drive Repair CBM 8250 - Searching

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vicassembly
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Disk Drive Repair CBM 8250 - Searching

Postby vicassembly » Sat Aug 19, 2017 3:09 pm

Can you point me to a reliable contact that might be interested in/able to fix a CBM 8250 disk drive? My guess is all the internals are fine and it needs realignment.

eslapion
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Re: Disk Drive Repair CBM 8250 - Searching

Postby eslapion » Sat Aug 19, 2017 4:19 pm

I suggest Ray Carlsen.
No one can do everything. Everyone can do something.

vicassembly
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Re: Disk Drive Repair CBM 8250 - Searching

Postby vicassembly » Sat Aug 19, 2017 5:22 pm

Perfect. I couldn't remember his name.

vicassembly
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Re: Disk Drive Repair CBM 8250 - Searching

Postby vicassembly » Sun Aug 20, 2017 5:35 pm

I reached out to Ray and here was his response. Any other ideas?

Hi Jonathan,
Sorry, but I don't do anything with the PETs or their hardware,
just the 8 bit stuff like a C64/128 and their peripherals. I don't
know anyone who works on PET hardware.

Ray

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Kakemoms
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Re: Disk Drive Repair CBM 8250 - Searching

Postby Kakemoms » Sat Sep 02, 2017 11:55 pm

I have 3 drives. I have been fixing and re-fixing them for a while, with the ultimate goal of being able to understand all about them. Its a really complicated design with two 6502s in the 8050/8250 and 6502+6504 in the x040s. Its diagnostic code (with the front led flashing) only pointing in a general direction, but usually not very helpful at all.

My primary problem right now is time. I finished a 6530 replacement adapter earlier this year and have one that works now. Apart from that, all parts can be found online. Most also in a working condition...

Your best bet on this is to do it yourself. Drive alignment isn't difficult, but requires an oscilloscope. Anyway, if things are out of alignment, you should still be able to format a new diskette, write something to it and read that again. Its all the other (aligned) diskettes that suffer.

PS: The 8250 has a higher density than for example 4040 or 1541, and are not compatible.

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Kakemoms
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Re: Disk Drive Repair CBM 8250 - Searching

Postby Kakemoms » Sun Oct 22, 2017 3:15 am

I hope to learn about the disk drives to better repair them. I have looked through the disassembly in the past, and the code tells more about the testing that then manual. I also found a list of tips on what to check for as the blink code only gives a general idea.

Maybe I will write a guide in the future once I get some more experience (& time..)


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