TM848 repair?

On 7/13/2020 6:10 PM, Chuck Guzis via cctalk wrote: I am especially impressed, for a few reasons.? Backstory: * I snagged 2 Model 12s at a CoCoFEST! a number of years ago during the show auction.? NO KBs * I then spent too much I am sure buying extra boards from a chap outside Atlanta who seemed to have sold these units for years. * Peter Cetenski was gracious enough to get me a few bootable floppies to try. * Then, when picking up the Atlanta parts in Chicago (they came via someone's back seat, I by plane), Jason Timmons loaded me up with more Model II stuff (external drive, front bezels, and a few Model IIs, including a batch of KBs. * Finally, at Tandy Assembly 2018, I picked up 2 external HDDs for not much coin) * But, I have been sitting on all this collection in unusable form since then.? It's taking up valuable space and I know I don't need it all, so I really need to get the units working I want, and then move the rest to a new home. * Still, all of the units collectively seemed a daunting task, especially in light of my not knowing anything about the platform. I don't even know how to list a dir in TS-DOS 2.0a (or whatever it is called).? LS-DOS uses dir, so there's that. Of the 4 units, 1 requires a new resistor (well, at least 1 new resistor), 2 were bad caps (now booting), and 1 has a good mech (swapped logic board with another one), but the logic board has another issue.? Resistor is good, cap is good, and VR is outputting 11.9VDC.? The stepper moves when booted, and the drive motor also looks to be running well.? I can see the LED showing the index pulses, but not sure where I should start (I have it sitting in a working mech, so I know all mech is at least marginally OK (was booting from the mech with another logic board). Jim -- Jim Brain brain at jbrain.com www.jbrain.com