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I'm finally done fixing my T1000

A

alank2

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We'll see if I attached the pictures properly on the new forum!

I had to replace the bad power supply with a Mean Well RT85B and I had to fix the optical sensors on the floppy drive.

I added a lo-tech 1MB board, 2MB EMS board, glitchworks XTIDE, and a GoTek in the drive B: position. I used a CNC to cut a hole on the left for a Yellow HDD LED and on the right for a toggle switch that selects which drive is drive A: and which is drive B:. It is tough to see in the picture because it is all black, but it turned out great.

The CM-4 that came with it does not have a very good dot pitch, but I adjusted the focus carefully on it and it is much better than when it arrived.
 

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Thanks, it does work on the fly. I was hoping I could use a standard DPDT switch if at least one side of the jumpers was in common on both the floppy and the GoTek and it was. The GoTek's ability to work with the T1000's low denstity floppy controller at 250kbits and yet have 255 cylinder images (2.25MB) is fantastic for moving files on or off it.

My only gripe is that it runs the motor of the floppy when accessing the GoTek and because the T1000 is only 4.77 MHz, it is often accessing and not accessing both starting and stopping the drive motor again and again. it seems crazy to me that they considered it a valid tradeoff to let all the floppy motor spin and didn't have a select on the drive itself that is combined with the motor signal to decide whether it should spin or not.
 
Interesting, I was thinking you'd be switching the floppy drive select lines, but you're toggling the drive 0/1 jumpers on the drives themselves? I don't think the B: drive should be spinning when accessing the A: drive; you might wnat to check to make sure your motor select jumpers or w/e on the Gotek are set properly. I struggled with that for some time when I was making a replacement floppy adapter for Trackstar boards, eventually I got it sorted out.
 
Correct, I'm swapping the DS0/DS1 jumpers essentially with the swtich. The Tandy 1000 does not have the floppy twist so A: and B: share a single motor line. I'm tempted to try to monitor the motor and drive select signal to see if it would be okay to bypass the motor signal and make it only active IF the drive signal is active.
 
alank2 said:
Correct, I'm swapping the DS0/DS1 jumpers essentially with the swtich. The Tandy 1000 does not have the floppy twist so A: and B: share a single motor line. I'm tempted to try to monitor the motor and drive select signal to see if it would be okay to bypass the motor signal and make it only active IF the drive signal is active.
Click to expand...

I still don't think your floppy should be spinning if the other drive is being read. I had the same problem on my TL (has no cable twist) and it was resolved (I think) by setting a jumper on my Teac 55b floppy drive:

http://retrocmp.de/fdd/teac/TEAC_FD-55_Jumper-settings.pdf

In my case I think it was the ML jumper; at first it was off, which meant motor would spin whenever motor signal was issued (for either drive.) I jumpered it and I _THINK_ that caused it to only spin when motor signal was active AND floppy was in-use (LED on).

I will take a look at my jumper settings when I get a chance.
 
I'll have to open it up and look at the jumpers again to see which ones it has - thanks!
 
None of the jumpers are ML - this is a model 54, maybe it doesn't have this option. I looked through the maintenance manual for it and didn't see anything about it either.
 
Looking good! Any notes or pics on your PSU upgrade? I've got a dead 1000 with no signs of life on any of the DC rails.
 
I assume your machine is a 'standard' T1000?

If so, is the fan running when you power the machine up?

The fan should be fed from the incoming AC supply before the switch-mode PSU. No sign of life on the fan either indicates that no power is getting into the computer itself, or the internal fuse has blown. You can visually inspect this (but make sure the computer is physically disconnected from the mains supply first of course).

Dave
 
The power supply itself began with a dead 12V rail. While working on it, my probe slipped off a component and it killed the 5V rail as well. I finally retrofitted a Mean Well RT85B power supply in it and it fit perfectly even in the existing metal brackets. Fan is still original 120VAC and so it the power switch. I can open the case and get some pictures of the power supply if it helps you!
 
alank2 said:
My only gripe is that it runs the motor of the floppy when accessing the GoTek and because the T1000 is only 4.77 MHz, it is often accessing and not accessing both starting and stopping the drive motor again and again. it seems crazy to me that they considered it a valid tradeoff to let all the floppy motor spin and didn't have a select on the drive itself that is combined with the motor signal to decide whether it should spin or not.
Click to expand...

In all fairness this wasn't Tandy's dumb idea, the common motor control signal was a decision made in the original Shugart interface specification, which Tandy followed, unlike IBM. (The reason I've heard repeated for IBM changing it is they were worried they'd melt the wimpy 63 watt power supply in the 5150 driving both motors at once; not sure I really buy it, but there it is.) It makes a certain amount of sense to spin them all up at once when you consider that operations copying data from one drive to another aren't particularly rare and if the other drive is already spinning you can save a little time that you otherwise have to spend twiddling your thumbs waiting for it to come up to speed and stabilize.

At least it isn't a set of older 8" floppies with AC drive motors, those spin the disks all the time. When Tandy changed from the Model II's AC drive to the 12/16's DC drives with start/stop they had to patch TRS-DOS with drive spinup delays.
 
You are completely right! I suppose a motor signal was better than nothing when they were just running all the time before that! I'm surprised that didn't create head wear, but were all the drives that can continuously able to "head load" and "head unload" ?
 
daver2 said:
I assume your machine is a 'standard' T1000?

If so, is the fan running when you power the machine up?

The fan should be fed from the incoming AC supply before the switch-mode PSU. No sign of life on the fan either indicates that no power is getting into the computer itself, or the internal fuse has blown. You can visually inspect this (but make sure the computer is physically disconnected from the mains supply first of course).

Dave
Click to expand...


I checked the switch and the fuse and those are good. The fan does spin, but oddly enough, it was disconnected when I took delivery of the machine.
 
alank2 said:
The power supply itself began with a dead 12V rail. While working on it, my probe slipped off a component and it killed the 5V rail as well. I finally retrofitted a Mean Well RT85B power supply in it and it fit perfectly even in the existing metal brackets. Fan is still original 120VAC and so it the power switch. I can open the case and get some pictures of the power supply if it helps you!
Click to expand...

I would certainly appreciate that if it's not too much trouble. Thanks!
 
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