I've been wanting a Turbo-R for a while but prices are just FAR too much for me to swallow so I've put it out of my mind until I stumbled onto a broken unit on Yahoo Auctions. The A1ST was advertised as non-functional...The seller apparently had gotten it broken and tried fixing it by swapping capacitors "and to practice".
Needless to say, he didn't get it working and sold it as "junk". I figured that perhaps I could buy it and could keep it for parts for a future project. In any case, a broken unit is what I bought and that is exactly what I received. The system, when powered up, simply had a black screen but it was outputting a video signal so it wasn't wholly dead. So then, I decided to see what I could do...maybe it can be revived?
Upon opening it, it did indeed have a recent recap but it wasn't done very well...there was some bad solder joints and at least one via was torn (this turned out to be the RED line on the RGB output). It also appeared that either the seller or the previous owner had attempted to expand the memory to 512K and had left behind the dip sockets and the various resistors and capacitors that are needed for the upgrade. It was also apparent that whoever installed these bits had run their soldering iron at 1000 degrees and left scorch marks on the board. The "new" memory was missing though so the best I could hope was to get it to boot with 256k.
I started with checking the capacitor swap...I printed out a copy of the schematics and verified continuity to every single capacitor. Surprisingly all of them checked out except for the one mentioned above. This took a couple of nights. Once done, I put my attention on the memory upgrade mods done...I started with checking continuity across the memory chip pins and found that pin #8 (address line #2) is supposed to have continuity across all of the four memory locations wasn't showing continuity. Upon close inspection, one leg as floating in air and the pad was completely missing! This surely as the reason for not working.
I ran a wire to create the continuity between the memory location and then proceeded to remove all mod work related to the memory upgrade as the work was very suspect. In fact, removing some of these pieces led to accidentally removing 3 pads off the motherboard...they were likely barely hanging on as there was evidence of scorching around them.
In any case, I cleaned everything up, slapped it back onto its base and plugged it in...and it immediately came to life! I'm absolutely thrilled that I somehow got my hands on a Turbo-R at a very reasonable price! I really did not expect to have a working unit! I spent the next few hours testing various games and making sure it boots to DOS and to its internal BIOS image...so far all good!
Now that she's working, I've got other deficiencies to worry about as the machine has clearly been scavenged for parts. I am missing the rear microphone adapter, floppy drive, floppy mount, and the keyboard (although complete) has a few letters that aren't working. In this state, I only have my MFR SCC+ SD with cart (with Sofarun) to run titles from and I can't seem to run ANY Turbo-R titles. I suspect that the issue here is simply that I don't know how to launch TR titles from my cart but perhaps something more is wrong with my machine and I don't know it.
If you made it this far, thank you and I have a few questions that I would love an answer for but please keep in mind that I know next to nothing about the Turbo-Rs.
1. The LED next to the "FDD" access light (I learned) shows the "CPU Mode" but what does the LED indicate? If lit, is it in Z80 mode or Turbo mode?
2. I recently purchased an A1WX machine that has a functioning floppy...can I pull it and slap it in the A1ST for testing?
3. Is there a rom/dsk image I can run from my flashcart that can test the various systems of my machine?
