Saturday, June 23, 2018

A Brace of CPCs..

That wonderful site, eBay, can be a strange place. Sometimes it's possible to find a bargain but most times it's basically someone either:

a) trying to rip you off by demanding ten times the actual value of an item - "it's old so it must be worth a fortune, right?"

b) trying to scam you - "please post to my brother-in-laws cousin in North Africa and I will send you twice what you asked by cheque"

c) selling broken crap - "sold as untested as I don't have the TV cable that I could get for £1 from Wilko 'cos I know my dog peed in it and it's never gonna work again.".

This time, I struck lucky. For a modest sum I bought a job lot of computers which included:

1 x Commodore Plus 4 with cassette drive, joystick and manuals
2 x Amstrad CPC 464

eBay Score!

There were no power supplies with any of them but, as luck would have it, I managed to acquire a Plus 4 power supply which could have been problematic - but the Plus 4 is another post to come. For the CPCs I just needed a 5V, centre positive supply which I happened to have already, and a video cable.

So, the units themselves. They look like they've been in a very dusty, dirty environment for a very long time. They may have been in a barn given the amount of dirt (not dust - actual dirt) that caked every inch of both of them.

A Bit Dirty
Yep - Dirty.

By peering into the user port (and then I took them apart) I can see that they are both slightly later versions of the CPC 464 as the motherboards only occupy half of the enormous case. The joystick port and headphone socket are at the end of the case too, rather than on the back. The motherboards are very slightly different to each other though. One has a 40007 ULA, the other a 40010. The 40007 is heatsinked and is located in the 'other' space for a chip on the board. In the photo below, there is a big gap with the outline of a chip just above the 40010 ULA - this is where the 40007 is on the other board.

Does this look big on me?

One of them has been clearly dropped at some point too as there is damage to rear of the case at the cassette recorder end (also visible in the photo above).

A very brief CPC464 history. Alan Sugar saw the computer market and wanted in. Amstrad released the CPC464 on 12th April 1984 following a bit of a false start. But with typical AMS business sense he made sure that there was software available and the machines just worked out of the box (unlike the Sinclair QL). It's worth reading the entire article linked to above. It's a surprisingly interesting read.

Clean up time. I decide to start with the non-damaged unit (comes with the 40007 ULA). Dismantling these things is straightforward. Six screws in the bottom, lift up the top carefully and remove the cable from the motherboard and the keyboard connections. Early 464s had a cable to connect the keyboard but later ones switched to using membranes, and it's this type that I have.

There are another six screws holding the keyboard to the top case and six more holding the motherboard to the bottom case. Amstrad must have over-ordered on screws...

Once the keyboard is free of the case, it's tempting to just start pulling keycaps off. Don't. On the back of the assembly are small black clips. Press on these gently to release them from the metal back and, once they're all released, the back plate and membranes can be removed leaving just the actual key assembly itself. Turn it over and it becomes obvious how to safely release each keycaps with little chance of breaking them. If you just start pulling key caps you WILL break them. So don't. 😀 Using a finger to hold one clip, use a screwdriver to gently push the other. The keycap should just pop out. 

Membrane and Backplate

Keyboard Unit (and glasses)

Be careful, there's a spring on the other side! Don't lose any of them! This style of key return is similar to that of Amiga keyboards. The main difference here though is that each key has a smaller spring embedded in it which is what makes contact with the keyboard membrane. These smaller springs are fairly well secured in the keycaps though so you shouldn't lose any of them. 😀

Keys and Springs - Don't Lose Any...

With all the keys removed, I washed the black plastic section with mild soap and water. It was, to put it mildly, a bit grubby.

That's Better.
Then, each key was washed and dried by hand. And there's a lot of them. It took about an hour to do all of them but the results are great.


It's worth noting that there are several keys that have metal bars attached to them, notably the 'shift' keys and the space bar. These need care but are relatively simple to remove. Press the key from the key side and on the back, gently push the bar out of its clips. If done right it shouldn't need too much pressure. Re-fitting is just the reverse procedure. Drop the clip into roughly the right position, press the key and gently ease the bar under its clips. Simples. 

Next, the case sections need washing. To do this I removed the motherboard (duh!) from the bottom section, and the tape drive, volume control, power switch, power LED (might be glued in - be careful!) and speaker from the top. There's another load of screws to deal with here and, if you have one of these computers and decide to do something similar I would recommend you take a picture before you start so that you can see the routing of all the cables when you have to put all those pieces back together...

Bath Time!
Once the case had been thoroughly washed down with a mild detergent and a bit of help from a nailbrush, they were toweled down and left to air dry.

End of part 1. In the next part, I put it all back together to see if it works...

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