The Spectrum +3 models are quite robustly built, so if you’ve recently purchased one, chances are it won’t need much attention. There is one exception though – you’ll probably find that as soon as you try and load a game from disk, or indeed do anything involving the floppy drive, that things aren’t quite functioning as they should.
One weak point of the design of the +3 Floppy Disk Drive (FDD) is that the rubber belt is quite prone to deterioration with age, so if you own a +3 or are about to buy one, you’ll need to know how to change it for a new one. Fortunately this is a reasonably straightforward process.
Before you proceed though, you’ll need to purchase a new drive belt – most readily available from the good folks at Dataserve-Retro.
If you’re ordering other components from Farnell then you can obtain the same part from them at this link.
- Philips head screwdriver
- No. 0 Jeweller’s screwdriver
- Tweezers (preferrably blunt ones)
- IPA and cotton buds (for cleaning)
Disassembling the Machine
Turn the computer upside down and remove the 5 case screws from the bottom, as well as the 2 additional screws from the side of the case next to the floppy drive itself.
Turn the machine right side up, and carefully remove the top half of the case. Disconnect the LED and keyboard membrane from the PCB, and you should then be able to locate the bare FDD drive to the right of the machine. This’ll be held to the bottom half by either one or two screws to the left of the drive, so remove these.
Finally, disconnect the data and power cables from the rear of the drive – don’t use too much force or you risk damaging the connectors.
The drive should now be free of the machine, so you can put aside all other components apart from the drive itself.
Disassembling the Drive
Turn the drive upside down on your workspace, and take your jeweller’s screwdriver and remove the three screws as shown:
These screws are all of slightly different types and sizes, and all have matching washers, so note carefully which goes where and store them carefully.
Also, from now on, don’t lift the drive from your workspace and specifically don’t turn it upside down – I’ll explain why later.
Now there are two PCB connectors to disconnect from the drive – one 4 way connector on the left of the drive, and a 2 way connector on the right. Again be careful and don’t pull them by the wires, use a small screwdriver or other implement to remove them.
You can now tilt the front side of the PCB upwards carefully to remove the old drive belt. If you’re lucky it’ll be intact and you can remove it carefully with a tweezers, but most likely the belt will have disintegrated and you’ll need to remove all pieces carefully.
You should also check the condition of the drive pulley attached to the motor – there could be some rubber residue left on this part. It’s imperative that this pulley be clean before replacing the belt, so clean it with some IPA and a cotton bud.
Replacing the belt
Again, with the PCB tilted upwards, using the tweezers carefully route the belt around the large pulley at the rear end of the drive, and then manoeuver the belt around the drive pulley. The belt should look like this when finished, be sure that it’s not twisted or misaligned in any way:
You can now reassemble the drive by plugging the connectors from the drive back into the PCB, and replacing the three screws on the topside of the PCB. Once the screws are in place you can now reinstall the drive back into the computer and test it out.
Haven’t you forgotten something?
Oh yeah, I mentioned that once the PCB screws are removed, that you shouldn’t lift the drive from your workspace until the belt replacement is complete and the screws are replaced. The reason for this is simple, brass coloured, tiny and a complete pain if lost – the write protect pin.
If you lift the drive and turn it upside down when the PCB is loose, you risk losing this pin. You won’t notice a problem until you refit the drive and test it by writing files back to it, to get the dreaded ‘Drive is write protected’ error message.
If the drive is laid flat during the replacement procedure, there’s really no way you can lose this pin, so save yourself the aggravation!
Note: some 3″ drives don’t have the pin, instead relying on a photodiode/IR LED setup, but you won’t know this until you take the drive apart, so why take the risk!
If it turns out you have lost it, don’t worry – replacements are again available from Dataserve Retro at the same link as above.