Vintage Synth Repair

>>One of the tiny pins on the data bus between the processor and the main memory was lifted due to a bad pick'n'place soldering at the factory.  Looking at the outputs on all of the pins on the bus one-by-one with an oscilloscope, I noticed that the output from the processor was 0-+5V and the input to one of the memory chips for the same trace was +2.5V.  Continuity test with ohmmeter showed broken solder connection.<<

this prompts me to mention that one of the most valuable tools I have in my toolkit is a jeweller's loupe. I had a problem with a yamaha an1x (the analogue modelling synth from 1997) where the bottom octave wouldn't work, but everything else was fine. I too found a pick&place IC (in this instance, the keyboard scanner) with one leg in the air by a fraction of a millimeter. quick dab & everything was ok. the synth had probably been like this since leaving the factory.

duncan.