Craig Sawyers <c.sawyers@...>
Mosyt instability is due tovoltages
and ripple.like you strip
the knobs and pull the front off.The push button switches are notorious on the 576 and other instruments on which they are used. I
was lucky enough to get a 576 free from a guy who worked in the BBC Technical Centre in the UK. It
had a characteristic problem with the older 576 of epoxy potting on the HT transformer (yours is a
late instrument after Tek had gone across to silicone potting, so you're OK there). The BBC were
going to put it in the skip, so this guy hauled it home intending to fix it, never got around to it
and gifted it to me.
Anyhow, to cut a long story short, this 576 had had a really nice life in a dry air conditioned
environment. But the push switches were all intermittent.
To get to one set, you have to take out all some, or all horizontal and vertical boards. You have to
take the knobs off these and undo the switch securing nuts, then a screw at the back. You have to
unplug a great number of wires (use your phone to take lots of close up photos so you can put them
back correctly). If you have the manual there are clear diagrams which show which colour wires go
Once you get them out, you will see a board with the offending switches on it. Using the flexible
nozzle on a deoxit can you get a good squirt down the inside of each switch. Exercise each one a
lot, then a final squirt. Reassemble.
Good luck - these curve tracers are well worth saving!