I have got the Acorn Electron working!
I’m actually quite proud of this one. My diagnostic was that the fourth RAM chip was dead and I was spot on first go.
I’d ordered the RAM from China as it’s so hard to source this stuff locally. While waiting for it to arrive, I realised I’d ordered the wrong type! (I’d ordered 4116, AKA 16k x 1 bit instead of 4164, AKA 64k x 1 bit). I quickly placed an order for the right type, and despite a 2 week gap in my orders, the correct RAM arrived first. (I can still use the 4116 in my Apple II systems so it’s not a loss)
When I got home tonight, I grabbed out the desoldering station, the soldering station, my home made extraction fan, some fresh solder and the RAM chips and got right down to it.
My process for desoldering is as follows:
- For normal desoldering, set the desoldering gun to about 380℃. I might seit a bit hotter for lead free.
- Mark on the underside which chip you need to desolder. Sanity check this. I have learned this from cruel experience.
- Wet the pins with the GOOD flux. I save the good stuff for desoldering and surface mount work.
- Add fresh solder to the pins. This helps break down the existing solder.
- Clean the desoldering gun between every 4 pins.
- Place the gun on a pin, then gently wiggle the tip back and forth until you can feel the pin moving. Then pull the trigger and keep wiggling. It should make a noise like a 6 year old with a straw and the last teaspoon of thickshake.
- Once all the pins are desoldered, get a fine screwdriver (I use a Jeweller’s screwdriver) to wiggle each pin. Each pin should move freely, or with no effort, it should ping free. Don’t force it! If you have to, add more solder to that pin and repeat step 6.
- Once all pins are free, gently try and remove the chip. I usually try fingers, and if that doesn’t work, I slide a thin screwdriver under one end of the chip and see if I can determine whether it’s just held in with friction or if there’s a stuck pin. If it’s a stuck pin, back to adding solder and more suction. Some pins (especially power planes like the ground or 5v pins) may need a bit of additional heat from the top side. Take it gently! We don’t want to lift pads 🙂
Once I had it desoldered, I reached for the sockets, only to discover I’d grabbed 18 pin not 16 pin sockets. Oh well. A quick trip to Jaycar was in order. (Hi Alice!)
Returning victorious with a few bucks worth of turned sockets in my hand, I soldered one in and cleaned off the excess flux.
(I know it’s odd having techniques for something as simple as cleaning flux, but I have developed one. First liberally douse the area in 99% isopropyl alcohol, scrub with a toothbrush, cover with a piece of rag, scrub through the rag with the toothbrush, repeat until clean)
I popped in the chip after carefully bending the legs to the right angle and turned it on and…
We have a BASIC prompt!
Now I had it all working, I reinserted all the screws and turned my attention to the tape deck. The connector that plugs into the Electron had unfortunately split due to old age, which meant it wouldn’t go into the socket.
This I fixed permanently by removing both halves of the metal shell of the connector itself, sliding on a piece of heatshrink material, returning the metal pieces, sliding the heatshrink over the metal shell and then shrinking it with my heat gun. They’re held in nice and tightly and the original plastic connector can be replaced without risk of further splitting.
After that it was a simple job to plug the cable into the tape deck, run the magic command to load the tape (CHAIN””) and press play. A few seconds later the game was loading and away we went. So excited!
So what next for this system? Well, I might make an upgraded tape deck cable for it. My tape deck supports motor control, so I may as well add it to the cable I have. Further down the track I’ll probably buy an ElkSD64, which adds a virtual floppy disk and an extra 32K of RAM to this unit. It would make a nifty little games machine at that point.