ULA: 6C001E-7 (date code 8416, probably made in Phillipines)
RAM: 48KB (OKI M3732H-20)
ROM: 16KB (NEC, socketed)
Trivia
Was sold as untested. Came with a German introduction manual.
Restauration Works
Composite Mod
ULA was not properly seated.
IC26 pin 8 was bent and not properly put into the socket, fixed.
TV signal was almost black. -5V and 12V was missing. Checked coil, but it was OK. Replaced TR4, TR5 and D19. 12V rail had 7V. TR4 and IC8 were getting very hot.
Diagnostics identified IC9 and IC10 to be defective, too. They were replaced. 12V was fine after that. -5V rail was -4V though.
Machine has a modified DC/DC converter in Sinclairs final revision. However C47 was missing, soldered in a 1µF cap. -5V rail gave -4.2V after that, which is closely within tolerance.
Diagnostics showed that the AMI ROM was defective. Unsoldered it and soldered in a socket. Found an old NEC ROM in my spare part box, which worked fine.
Recapped the machine. 7805 and heatsink was replaced with a Traco Power DC/DC converter.
Case cleaned. Faceplate is clipped and was removed for cleaning.
Brittle membrane replaced with a replica.
Four case screws and the PCB screw were missing and have been replaced.
Known Issues
Minor faceplate damage. I decided to keep it like that, to show that the machine has a history and was once bringing joy to its owner.
