BEGINNER getting started (Was: Diagnosing and Reparing Commo

My ears are burning :-) I appreicate the problem. The sort of socket set I would _like_ to buy, if I was buying one now, is over 10 times the price of a 'crappy' one. However, there is a case to be made, I think, for buying the few tools you need -- and getting high quality ones -- rather than buying a large set of cheap tools. FOr example, you mentioned taps. I tend to buy only the sizes I need, anf get good ones, rathen than buyign one of the cheap imported srts with plenty of sizes I don;'t need and made from 'steel' that appears to actualyl be cheese... There are sill pletny of kits out there -- Velleman, for exmaple. But they are gernally not as 'complete' as Heathkits. You find that thigns like th box, mountign hardware, connectors, etc are not included. Often you get the PCB and the components to put on it, and nothing more. They are also less educational as regards electroncis than older kits. Many now incldue a programemd microcontroller and you do nto get the source code. SO you cna't really understand what it's doing. Unlike a circuit made from discrete transistors (or valves) where you can understand what is going on. as I said, assembly kits is a good way to learn to use the tools, but it's not all you need to be able to do. It depends -- a lot -- on the computer. I've writen a set of articles for HPCC (and the only way to get them at the moment is to join HPCC, sorry!) on repairign the HP9800 calculators. I do include an intital checkout procedurte, but must of it would not apply to other machines. That said, there are some basic tests that youy do on just aobut any microcomptuer : 1) Check the power supplies. Cheak the voltages nad check them for ripply. Power supply problems are suprisingly common, and no computer works porperly if it's not powered properly 2) Check the processor clock signal. 3) Check the reset signal. Make sure the processor isn't being held reset (or worse that it's not being reset at mains frequency due to a problem with the power-OK circuitry, yes, that's csuprising common too). 3) Check if the processor is doing anything. Is it attempting to read memeory, for ecample 4) Cehck all data and adreess lines for activity. ALl data lines should be toggling,. the low-order address ones shoudl be too. It's posible it's (correctly) running a small routine and thus the high order address lines might be steady 5) Check to see if it is acessing the firmware ROM 6) If you have a logic analyser, grab the data and address buses and see what it is acutally trying to execute. Does it make sense? Do jumps cause the address to change in the right way? Yo uand I have a lot in common... -tony