A Tandy 1000 RL HD Repair Story

The Tandy 1000 series is a really interesting series of clone PCs.  For me, the fact that it’s an American designed PC clone and not an IBM product makes it more interesting.  I'm not fond of IBM, for reasons that I've mentioned before.  As a kid, Radio Shack was always my favorite store, and I remember wanting one of their computers.  Today I have a strong interest in these XT class machines because of the limitations that this processor imposes.  I have one of the first XT based PC clones, the Compaq Portable from 1983, but this would have been one of the last XT clones, a Tandy 1000 RL HD from 1991.  Tandy took the XT just about a far as it could go, with really good built in color video and sound.

One of my retro computing friends is really into PCs and has a great deal more knowledge and experience with this era of systems than I have.  He's shared his interest in the Tandy 1000 series of computers with me, and I’ve been wanting to get one as I've become more interested in the history of PC gaming, learning from Neil @ RMC's excellent Tea Break series, and from the 8-Bit guy's video here.  So, when my friend started having trouble withe one of his 1000 machines and offered it to me as a repair project, I jumped on the opportunity!

The computer was non-functional and since neither my friend or I had another one, we were not able to do parts swapping to determine exactly where the fault lie, but he was pretty certain that it was the Power Supply, which made the most sense.  He pointed out this video from the YouTube channel Necroware about making a Power Supply for a Tandy RL using a 12V Power Supply and a Pico-PSU, a rather creative idea.  Also, I looked on the Vintage Computer Forums and read this article about buying a different off the shelf power supply that could work.  Unfortunately I did not think the Jameco power supply would fit inside the slimline case of the Tandy 1000 RL, so I ordered a Pico PSU that I found for sale on eBay.

When the Pico PSU arrived, I carried out the Power Supply upgrades very much like what you see in the video.  During the repair, one of the mistakes that I made was taking the main power switch apart to see how it worked.  These switches have a lot of small parts and springs inside and I was not able to get the switch properly re-assembled.  As a work around for the broken power switch I wired up the PSU to be on all the time, but sadly the new power supply didn’t work.  In digging in a bit more on this, I remembered that the -12 Volt current rating on the Pico PSU I bought was 100 mA max.  The rated current of the computer was also 100mA, so I thought that this would be OK when I bought it, but it was not enough current (it's likely that aging components on the motherboard consume more current than they used too).  The power supply voltages all looked good, but the moment I plugged into the Motherboard, all the voltage would go to zero. (Short circuit protection.)

At this point I still suspected that I had a bad power supply, but I was wondering also if there was something going on with the Motherboard.  I setup a saved search on eBay for a Tandy 1000 RL for parts / not working.  I also tried to find another Pico PSU with a higher current rating on the -12 volt rail, but that was a dead end at least at that poin on eBay.  I ended up putting the entire project on hold for several weeks.  I didn’t know what to do, and I had other things to work on, so the project sat.

Then something unexpected happened, a cosmetically damaged but working Tandy 1000 RL HD came up on eBay from my saved search.  I tried not to get too excited about this since it was a 7 day auction that might have gotten bid up, but the seller had done a good job of documenting the condition of the computer, so it was not going to collect top dollar.  I put in a minimum bid at the beginning of the auction and I had to raise my bid once towards the end, but I ended up getting the machine for what I considered a fair price even with the shipping.

When the "new to me" machine arrived, I was able to swap in the power supply and confirm that the first machine was working.  It booted for me for the first time, always an exciting moment! The end result of the troubleshooting exercise was that the Power Supply had been the problem all along.

The next problem I faced with this machine was the keyboard.  My other XT machines have built in keyboards, so I didn't have a working XT Class keyboard.  In talking to several different retro computer friends I learned that these are quite difficult to come by now.  Perhaps the cheapest solution is the AT2XT converter project.  These are for sale on eBay, but I have not received and tested mine yet, so I won’t link to that.  Another good solution is a “Switchable Keyboard” that can do either AT or XT signaling.  These were more common during the transition time between the standards in the late ‘80s early ‘90s.  I was able to find one of these on eBay for a reasonable price.  With this keyboard plugged in I was finally able to use the Tandy 1000 RL for the first time after owning it for months.  This was another high point for me, and I really savored the moment.

One of the first things I did was fired up my copy of Planet X3 to check out those Tandy Graphics and Tandy Sound used to the best of their ability.  Planet X3 never looked or sounded so good on any XT class machine!  I look forward to digging in on other games of the period that have a special Tandy version.

The next order of business for this machine is to get working storage solution.  The machine I bought on eBay had a hard dive in it, which surprisingly still worked after shipping, but died within a couple of weeks after that.  I had an XT-IDE card to put in this machine, and installed that in the machine for Mass Storage.  I'm out of 2GB CF cards, so I'm currently running the machine off an old 16MB CF card that I had laying around.  Running out of Hard Disk space so quickly is part of the Retro Experience, but I do have some larger CF cards on order.

So that's it for the Tandy machine for now.  I may eventually find the correct "Tandy Enhanced Keyboard" for it at a reasonable price, but that's really about the only other upgrade I'd like to put in this machine, and in the meantime I will just continue to enjoy it like it's 1991.