The refurbishment process starts with a basic inspection of the computer as received. Work is often required to repair the circuit boards, followed by a complete electrolytic capacitor change. The capacitors fitted to Spectrum 16k / 48k / 48k+ machines are often a cause of problems, so a blanket change is done to prevent further faults developing.
Capacitors ready for fitting. I now use Dubilier capacitors which are a quality range, blue in colour similar to the ones used originally. I also modify the computer to output composite video using the original modulator socket. This is a non-destructive upgrade that can be undone if the original TV out is required.
A further photograph after the new capacitors have been fitted.
With the standard 48k and 48k + Spectrums, a major problem is excess heat inside the case while the computer is running. On the 48k+ model there is room to fit a heatsink on the ULA (the part that most usually fails through getting too hot(, but on the rubber keyed models there isn’t enough room. It is possible to fit a heatsink by removing the ULA socket and soldering the ULA directly to the main board, but as this makes future fault-finding much more difficult and doesn’t really resolve the problem too well as the heat remains in the case due to lack of ventilation.
An alternative method of cutting down the heat is to remove the original voltage regulator heatsink and replace the original voltage regulator with a modern alternative. This is my preferred method and I now fit this type of regulator to Spectrums that I refurbish.
The edge connector is now cleaned so that any peripherals added later will get a decent contact.
Also, I replace the keyboard membrane as a matter of course on all rubber key Spectrums. Most membranes are affected by the heat and those that haven’t completely failed have probably a very limited life remaining. Spectrum Plus models (as well as Plus 2 and Plus 3 machines) are rarely affected so a decision as to whether to replace is made on a machine by machine basis.
finally, the computer case and keyboard mat are cleaned prior to final assembly;
And the computer is then thoroughly tested to ensure it is in perfect working order.
