I have been traumatised by my turntable. Just to recap, it won’t zero. It will run round to the next index point no problem. It won’t zero though. It moves half an inch at most and then stops.

I spent Thursday trying everything I could think of for 3-4 hours. I cleaned everything; many times.

I mulled it over and surfed the Internet, a lot. No joy.

At 11:30pm, I eventually reserved a batch of IR sensors and LEDs at the local Maplins. I arrived on Friday morning as they opened and picked them up. They cunningly hadn’t marked the sensors or LEDs and didn’t know which were which.

I swapped out the two on the turntable and wired them in every permutation. We tried TV remotes, cleaned everything, again. I can get it to go round and round when stopping if I wire the components in the wrong way round… At 2pm I had to give up and tidy up as I had people coming the next day…

More surfing. Still going nowhere.

Saturday, my friends came round, turntable still not zeroing so after they went I mapped every wire and contact. I can now take my turntable apart blindfolded! More surfing, still going nowhere.

I wondered about wiring the motor output of the decoder directly to the bridge motor but then I would lose the indexing which seemed a real shame. I gave up at midnight.

Sunday morning and I could’t sleep so I went up and wired the original components back in… Then wired the LED the other way round and it ran 3 inches before stopping when I pressed zero. Result.

I put the bridge close to the zero point (not for the first time) but this time, it stopped at what I thought was the right spot. Tried the bridge further away; it didn’t work. Move the bridge closer, it does.

Hmm. I wonder if the ambient light is confusing the sensor and it thinks it is there already but the bridge shades it enough that it almost works every time.

I’m hoping this is close enough, for now.