The Most Challenging Composite Mod - In the WORLD. (Maybe not..)

A short interlude before I start playing with cassette recorders..

My Acorn electron is still waiting for some more attention, mostly because I don't have the correct cable to load cassettes and I don't have the 'retro' budget to splash out on the available SD card type options. 

An Electron walks into a bar...

But one thing I hadn't realised was that the composite output is actually monochrome. I was quite surprised at this as I knew I'd seen videos of people using their electrons with gloriously garish colour through composite. Well, it turns out a fact well known to Electron aficionados is that there is a very, very simple mod that can be made to change the monochrome output to colour. This was completely unknown to me, of course, but here's the proof, direct from the Electron service manual:

So, according to this, all I need to do is bridge the link labelled 'LK4' and it will add the chrominance component to the composite output i.e. monochrome becomes colour.

Time to break out the screwdrivers.

Electron bottom...

Gratuitous Action Shot

Under the hood.

With the motherboard completely removed from the case I just needed to find LK4. It wasn't too hard to find.

LK4, whereart thou?

Gotcha!

With the link located I decided to take a leaf out of Mark Fixes Stuff's book and, instead of just soldering a link across it I would add a couple of header pins to allow a jumper to take it back to monochrome i.e. it would be reversible.  After a bit of scrabbling around in the spares box I liberated a four pin header from an old Sky box motherboard and proceeded to snap it into two two pin headers.

First soldering job was to clear the two holes of the existing solder. This was easy enough with a dab of flux and some solder wick. Surprisingly, the hardest bit was soldering the pin header to the board. Holding the pins in place with my finger resulted in several minutes of inappropriate language as the rapid transfer of heat through the pin, fully complying with the expected laws of thermodynamics, burned my bloody finger. 

Trying to hold the pins with pliers proved tricky to say the least. After another minute or two of appalling profanity I manged to get one leg holding on by the merest sliver of solder. This was enough to allow me to solder the other leg and then finish the job. It's not the straightest but it's only got to hold a jumper. Annoyingly, that transistor (see below) made it tricky to get one on. A firm push of the transistor moved it a sufficient amount to remove that problem..

Lovely jumper.

But did it work? After re-assembling the case and doing all the screws up I realised I hadn't taken any pictures of the Electron in monochrome, so no Before and After pics. But here's the evidence that my traumatising injury (slightly burnt fingertip) was worth the agony (mild irritation).

Colours. (Ignore the reflected bald head.)

And now, back to those pesky cassette recorders. (Well, soon anyway.)