Vintage Synth Repair

>>> I felt bad for the guy - so I picked up a cheap digital meter ($3) and sent it to him - he now has no excuse not to test his gear. :-)<<

I like that story. good karma....


>>The big difference between the eras is the ICs on the boards.  Everything from the mid 80's on is microprocessor-based.  Modern stuff is made by pick'n'place robots and 1970s equipment was hand assembled and soldered.  The components were a lot bigger and could be repaired easier.  The technology for populating and manufacturing the circuit board itself is much more advanced today than it was thirty years ago. 
But the boards of today are almost impossible to repair.<<

I'm inclined to agree, but nevertheless you will sometimes get a rewards for persistence- these expensive multi-layer boards covered in VLSI do occasionally have manufacturing defects like the pick&place bad joints already mentioned. additionally, they can go wrong if airborne contaminants accumulate on the surface & change the electrostatic properties sufficiently (I had a panasonic walkman that would varispeed if the weather was damp- eventually traced this to muck in the servo circuit being electronically activated by humidity). also watch out for simple psu problems (bad bridges, electrolytics, regulators), cracked boards, failed switches, bad joints on sockets, bad opto-isolators on midi gear, this sort of thing can have a non-technical owner writing something off & dumping it for pennies on ebay, while service shops may not have the time or patience to stick with it, & tell the customer it's not worth them even looking for the fault.
besides all this, those of us with engineering in our blood are always up for a challenge, & always looking for the kick that comes from breathing life back into some recalcitrant electronica, especially if it's related to music.

duncan.