On 11/18/2012 2:19 PM, Charles wrote:


"mike" wrote in message ...

Big snip.

I am pretty sure it's a gain problem perhaps related to a low supply
voltage. Once it started, it ran fine for days. When gain is on the
hairy edge, oscillators get iffy. They have trouble starting.

I've never seen the schematic, but I have done design reviews on
the FG501/2/3/4.
It's extremely likely that the oscillator is a cap with switched
current sources and threshold detectors determining the amplitude
of the triangle.
"Trouble starting" is likely not relevant.
You need to consult someone locally who knows how 1970's function
generators work...or do some googling. Well-meaning random inputs
from net denizens who don't have any relevant experience is often
counter-productive.

The FG507 topology is likely to be very similar to this:
http://bama.edebris.com/manuals/tek/fg503
with some sweep stuff bolted on.
The sweep is irrelevant except that it's possible for
one of the sweep tentacles to disable an otherwise working
triangle generator.
The components used to implement the circuit vary over time,
but the topology hasn't changed in decades.

This one is probably closer to the FG507 and worth downloading,
but understand the FG503 before
you delve into the complexity of the FG504. There's some stuff
in the 504 that is counter-intuitive and put there to patch up
some fundamental design flaws without a complete redesign.

http://bama.edebris.com/manuals/tek/fg504

Nice people here, all trying to be helpful and I appreciate that.

Thanks Mike and thanks to all of you.