Welcome to the list! I'm also from the UK, I've been restoring classic computers for the last 20 years (and don't intend to stop now). Why do you suspect a resistor? That's one of the least likely components to fail. What esactly has happened to the machine, and what's the fault. There are many very knowledgeable hardware types here, but none of us are mind-readers :-) And if you've done something stupid, like cut the wrong resisotr when doing an upgrade, tell us _now_, not after we've spent several hours with the schematics and 'scope... I have lost count of the number of components I've replaced on PCBs over the years... Suffice it to say that many of us here don't worry at all about component-level repair on through-hole or normal SMD boards. It's just something we do. I've got many manuals that tell me a particular module can't be repaired. I just ignore them, and write my own repair docs if necessary... AFAIK there's nothing that difficult to replace in an A600, but I am not an expert on this machine (heck, I am not an expert on anything). [...] My second computer was a TRS-80 Model 1 (my first, FWIW, was an MK14, yes I still have both). I now have a Model 3 and Model 4, and several CoCos. And schematics, etc for all of them. -tony