A mug's eyeful.

There used to be a reason for vintage computer collectors to head to car boot sales. Tons of stuff going for pennies used to adorn the tables of the happy 'booters' (well, maybe not adorn but there used to be a fair bit). An Amiga A500+ for £3, a CD32 controller for a fiver, Commodore 64 (boxed) for a tenner etc etc.

Those days are long gone. Anyone who has anything remotely vintage either sticks it on eBay or heads to the car boots with ridiculous prices in mind. Things are so bad now that there are even Facebook groups dedicated to the delusional people of eBay and the whacky and bizarre prices that they think their stuff is worth. My favourite was a chap in Scotland who for several months put his boxed Amiga A500 on eBay for the sum of £1000 starting bid. If that had been serial number 1, signed by Jeff Porter and hand delivered by R J Mical, it might have been worth it. In reality, they're worth less than 1/10th that.

I digress. 

A few weeks ago, Crashed Jr(1) let me know of a 'PC' that was at a local fete for a very reasonable price. He sent me a picture and it turned out to be an Amstrad PCW9512. 

I know this! It's a CP/M system..

For those of you not in the UK, the Amstrad PCW9512 was one of a range of low cost PC like machines that dominated the early low-end small business computer market. I actually used one of these many, many years ago at an estate agents I worked at. It uses CP/M and has a primitive word processor and, originally, came with a printer too - no printer with this one but that's fine.

So, does it work? Well, the thing with these machines is that they are very much built to a price point so to actually get this thing up and running requires either the word processor disk or the CP/M disk. Switching on with no disk in the drive gives a beep and a white screen and nothing else. Without the disks, this is a lighter than you'd imagine paperweight.

And on the subject of disks... The more astute of you might have spotted that this thing actually uses 3 inch floppy disks rather than the more usual 3.5 inch disks. The story is that Alan Sugar managed to blag a boatload of 3 inch drives dirt cheap and so they went into every machine Amstrad generated that used floppies (CPC6128, PCW8256 etc etc). Not sure if there's any truth to that but anything's possible

Anyway, this unit did exactly as expected when I got it home, i.e. it has no disks so it just shows a white screen. I did have a 3inch disk for a PCW8256 but I didn't realise at the time they aren't compatible so when I put it in, nothing happened. But not exactly because of the incompatibility..

The floppy units in these machines use a drive belt to turn the spindle motor that makes the disk spin. And we all know what happens to rubber belts as they age. They turn into a thick, black goo that is horrible to remove from everything. To check the state of the belt I had to take the back of the machine off, then dismantle the base from the CRT so I could get the drive unit out. After taking the back off I realised I wasn't the first person to do this.. 

There are two controls on the side of the unit to control the brightness and contrast. The contrast knob had been hot glued. Oh dear. So as I took the case off, both of the potentiometers for the controls basically fell apart. Dangnabit. I managed to collect the bits and then desolder the bar that they were both attached to. 

Broken. Darnit.

After a bit of head scratching I realised that all that had happened was that the protruding control knobs were held on by plastic stakes that were melted to hold the front cover plates on. By gluing the plates back on - and trying to avoid sticking the knobs too - I could probably get away with re-installed these original ones. So that's what I did. I gave the knobs a twist to make sure they didn't stick and then let the glue overnight to cure. And the knobs were stuck solid the next day. Solved that by a firm twist with a pair of pliers. 

Fixed! Yay! Don't play with the knobs
or they may drop off.

Back to the floppy drive. The belt had, as predicted, become a sad strip of goo and needed to be replaced.

Belt has started to disintegrate

Gooey belt stuck to the main flywheel. Yuk!

In the course of moving the little green circuit board I heard a slight 'plink' of something hitting the floor. Unbeknown to me, these drives, also clearly built to a price point, have a small metal pin which drives the write protect function. This pin is not secured and simply drops into a tiny hole in the drive body. And simply drops out if you're not watching carefully..onto a small piece of patterned carpet...with the debris of many hours of soldering and other vintage computer restoration activities. 

Bugger.

Of course, at the time I didn't realise this was the case. But somewhere in the depths of my slightly confused middle-aged brain an Emergency Action Message was triggered that told me I should check the floor for something that I had never laid eyes on before. And sure enough, after half an hour of crawling around in the dust, solder blobs and occasional annoyed spider, I found it.

Dropped pin. Gah!

After checking the circuit board I located the write protect switch and made sure the pin was dropped into the correct hole. 

Back to the drive belt. After cleaning away the remains of the sticky old belt, which involved lots of scraping and cleaning with isopropyl alcohol, fitting the new belt was simple. The PCB was screwed back into place, which also then secures the write protect pin (grrr) and everything was ready to be re-assembled.

New drive belt goodness.

Controls re-installed

With the unit back together all I need now is a disk with the correct software on. I have a disk image for CP/M for PCW9512 but there are a couple of problems.

I have an additional floppy drive which is 3 inch but when I plug it into power, the drive makes 'chunk chunk' noises and the power supply (courtesy of the Cifer) goes into meltdown. A closer inspection shows that there are leaky caps just at the power connector.

Ohhh, another 3 inch drive.

 

It's an EME-01 (apparently)

Track damage just above the orange 
wire (mid left)

More track damage under the brown wire

Although I didn't have a full set of capacitors I did have the two values next to the power socket and a couple more on the main board. And changing them solved the problem. Bizarrely, that's the second time that changing the caps has fixed a fault and both times it was a floppy drive.

This 3 inch floppy drive is fully compatible with the Shugart standard. This means that I can use the awesome Greaseweazle with it. I managed to get a record of the disk that actually came with this drive - which was for the PCW8256 - using the Greaseweazle software with the intention of writing the the CP/M image for the PCW9512 back to that disk. 

But there are two major problems. This is only a single sided drive. The drive in the Amstrad is double sided. 

Second, the additional floppy drive only supports 40 tracks per inch whereas the PCW's drive is 80 tracks per inch. 

Arse.

Looks like I'll be heading to eBay for a CP/M disk then. Darnit.