tl;dr
If you are interested in working with or restoring vintage computers, avoid the Tandy 1500HD. You will only be wasting your time and money.
The full story:
I picked up a Tandy 1500HD from Goodwill recently. It came with 2 power supplies, an extra battery (probably dead too), original diskettes, and original documentation.
Once it arrived, I triaged it. The display wouldn't light up, but it would flicker. No beeps from the machine as it tried to boot. The hard drive would spin.
I took it apart to see what was going on. No leaking capacitors. Good sign. The clock battery looked good (i.e. not leaking but probably dead). The Tandy 1500HD kept it's config in flash, so the battery was only there to keep the real time clock going when powered off.
I wish I had done more research on this before I paid for it. The drives (both floppy and hard) are completely proprietary and not replaceable - and you can't even update them to flash drives like many old computers today. The interfaces are completely non-standard.
The floppy drive belt was almost goo. It loosened over time and just came off. I attempted to replace it, but no go. I figured that maybe I could get at least something working on it. I also found out that the system won't even POST unless the hard drive is hooked up.
The display problem was simple. The cable inside the display came off. The old foam simply had broken down over time, allowing the cable to be pulled from the connector enough to not make a good connection. That, at least, was a simple fix.
The bottom line is that to get this back to working condition, I'd need to replace the hard drive and the floppy drive. Either with old stock or refurbished parts, or with modern replacements. Unfortunately, neither exist.
Trying to find technical documentation on this computer was not fruitful either. The usual places simply had nothing on them. No repair guide. Just PDFs of the documentation that came with the computer and some jumper settings (which, BTW, were incorrect).
So I wasted my money on this. Hopefully you'll read this and not waste yours too.
