We received a very dirty power supply for a 3M M79 24 Track Master Recorder from a customer.
He told us that it would sometimes work OK and sometimes not. When we tested it before opening it up, we noticed that it would come to life after going dead if you moved the cabinet slightly! Hmmmm.
We opened it up and dirt literally fell out! Lots of bits of recording and splicing tape, dust, mouse droppings (?) ...AND a RAZOR BLADE....stuck in a very BAD location!
The razor blade shown in the picture is just as we found it! Stuck right behing the voltage regulator, shorting (sometimes) to ground ! Not a good thing!
We did a full cleaning, inside and out, replaced ALL of the 'corroded' power pass transistors (a whole bunch), cleaned ALL of their connectors, recapped the whole unit. Replaced a couple of voltage regulators. Then full load tested the unit after 24 hours in our Hot Room. ALL IS WELL NOW! We even sent the razor blade back to the customer with a commemorative photograph!
PRO AUDIO
