BBC Micro Model B

I have 3 BBC Micro units. The story of how I ended up with 3 is a bit of a long one!

I was given the first unit by friends who were clearing out a load of old computer kit around 2007/2008. It was working when packed away but sadly being uncovered in a loft for 10+ years had taken it’s toll on the computer. My Dad told me that my Uncle had one back in the day, so we took it to him one weekend to have a look. He still had his unit but sadly it was missing a power supply. We connected up the PSU from the unit I was given and both were showing the same symptoms. We made an assumption the power supply was the issue, but after eventually sourcing another one, it was found the PSUs were both good. Eventually on another weekend, my Uncle dug out all his BBC Micro gear and I came home with the lot which is where machine 2 came from.

Eventually we gave up trying to get one of the 2 machines going and my Dad managed to get me a working unit from eBay to use with the masses of software, disc drives and accessories I’d acquired with the 2 previous machines. This is the machine pictured above. It has always worked flawlessly except one day when my Dad was helping me fit a sideways RAM expansion and smoke came pouring out the PSU vent! This was easily remedied with a cap kit from eBay and I have since replaced the RIFA caps in all 3 of the computer’s power supplies.

Not being one to give up, much more recently (~March 2019) I managed to revive the 2nd computer which was my Uncle’s. All that was wrong was a bad RAM chip, so after building an inverter and following a YouTube video to work out which chip was bad, I used my de-soldering gun, removed the original chip, fitted a socket and pushed one of a pack of spares I’d found on eBay in. Miraculously the machine fired on and showed the full 32K of RAM available with no graphical glitches.

I invested in an oscilloscope and was using it to try and diagnose the first BBC Micro I had received. Unfortunately the fault had gotten worse and it had stopped producing the continuous tone on power up altogether. I struggled to pinpoint what was wrong with the machine but knew there was a high chance of at least one bad RAM chip based on the original symptoms. Eventually I enlisted the help of RetroClinic to repair this machine and by the last week of April 2019 it was running like new again. It had a ridiculous amount of faults I would’ve struggled to diagnose on my own including 5 bad RAM chips, bad CPU, bad serial ULA and a bad IC on the keyboard to name just a few! Later on, another RAM chip that wasn’t one of the 5 replaced by RetroClinic failed and I managed to diagnose and replace it myself pretty quickly using the knowledge and spare parts I’d gotten when sorting out my Uncle’s one.

My main BBC Micro is the one my Dad got for me on eBay and currently has the following upgrades installed:

  • Solderless 30KB OS Shadow RAM from BooBip
  • Solderless 32KB Sideways RAM + 32KB ROM from BooBip
  • Solderless 64KB EEPROM from BooBip
  • Acorn Speech upgrade reproduction from RetroClinic
  • BBC Micro Model B Econet upgrade kit from BeebMaster

I also have the following “cheesewedge” expansions:

  • Acorn Teletext Adapter (1MHz Bus)
  • Acorn 6502 Co-processor (Tube Port)