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TRS80 - Model 4 disk error

Lorne said:
I'm very happy they're fixed, and I'm looking forward to getting them back, and into the Model 4.

Just a thought: if you're ever planning a career change, try to avoid applying for anything with the words "technical report writing skills" in the job description! :)

Thanks Dru,

Lorne.
Click to expand...

Well, looks like I'm gonna hafta fix Drive B gooder because, although the original problem is fixed, I'm getting sporatic read/write errors on it and it don't go out 'til I'm happy with the way it's working.

Hey, boy, whatchu sayin' 'bout my rightin' skilz?

If you're going to be noisey about it, both drives had dried out stepper motor bearings. The nice thing about having the units in front of you is you can touch them and, moving the heads was a chore all along the length. It's not something I've seen before, but, that's what it was.

A little precision placement of 3-in-1 on both ends of the stepper motor shaft and then moving the heads by hand fixed this up nicely and then cleanup of the shaft ends with some denatured alcohol to prevent gunk buildup.

I regularly run floppy drive for 24 hours without any apparent ill effects.

Drive A is working perfectly, according to my diagnostic and alignment programs, but, I'm going to have to figure out what is up with Drive B.
 
Reminds me of that old joke --

WHAT! $250 just to fix it by hitting it with a hammer???

Hey, you gotta know where and how to hit it!!!
 
I'm thinking that Drive B has a flaky 3470 read/write amp and that was probably the ORIGINAL problem. The steppers just dried out from sitting for years baking somewhere.

They are hard to come by, but, I believe I have a/some 3470s kicking around, it's just a matter of finding it/them.
 
Druid6900 said:
Yup, it's a buck for hitting the part and 249 bucks for knowing which part to hit :)
Click to expand...

And, you have to have a fancy-schmancy professional-grade hammer calibrated to the exact striking force, and laser-guided to land in the correct spot for optimum performance. Those kinda tools don't come cheap, y'know.

--T
 
Druid6900 said:
I'm thinking that Drive B has a flaky 3470 read/write amp and that was probably the ORIGINAL problem. The steppers just dried out from sitting for years baking somewhere.

They are hard to come by, but, I believe I have a/some 3470s kicking around, it's just a matter of finding it/them.
Click to expand...

I've got a couple of dud Tandon drives here, so if you can't find the parts, and it's something (I don't even know what a 3470 looks like - it's a chip?) that I can pull off one of these, let me know. (Or, I can replace your parts with the ones from these later).
Thanks,
Lorne.
 
Lorne said:
I've got a couple of dud Tandon drives here, so if you can't find the parts, and it's something (I don't even know what a 3470 looks like - it's a chip?) that I can pull off one of these, let me know. (Or, I can replace your parts with the ones from these later).
Thanks,
Lorne.
Click to expand...

Yes, it is an 18-pin IC and, on the TPI board, it was the only one socketted (what does that tell you?)

Suddenly, they don't seem to be so hard to find and not very expensive at all.

Give me some time to confirm that's the problem and then I'll sacrifice one of the ones I have to fix it.
 
Another Update:

The drives are on their way back to me.

Druid got Drive A working with some lube and TLC, but he figures that the Drive B stepper motor was just too siezed up. He figures it must have been sitting somewhere in a humid climate for a long while and got corroded (that certainly didn't happen here!).

Once I get them back in the Model 4, I'll make one more post to (hopefully), say everything is working fine.
 
Got the drives back from Druid today.

I put them in back in the Model IV, powered it up, and at the "Diskette ?" prompt, I inserted a boot diskette.

Then I saw a screen I'd never seen before - ie: it booted !

Druid done fixed 'em real good !

Thanks for all the help folks.

This thread can now be considered closed.

.
 
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