Uh oh...

Hi. I have a newly-built Etherwave kit. I was trying to tune the pitch circuit yesterday, but could not get it to work as the instructions said. It sort-of works now, except for the fact that when I get too close (within an inch or two) to the pitch antenna, it pops up to a very high note, and holds until I turn it off. Does anyone have any suggestions on how to fix this, or is it a component problem or something like that? Please help!

HELP!!! I can't even use my etherwave now. It seems to be stuck in a very, very high pitch. I have e-mailed Moog directly several times now with no response. Does anyone have any ideas at all how to fix this tuning issue, or do I have to send it back? Any help at all would be greatly appreciated :-)

I'd telephone Moog and ask to talk to a technician.
Ryan Cox there recently did work on mine and was great on the phone when we were figuring something out.

I would start by adjusting all of the tunable
inductors to the halfway point. Carefully
adjust the inductors all the way clockwise and then all the way counter-clockwise while counting the number of turns. Adjust each one to the halfway point and step through the procedure.

If it still doesn't work you should find someone
with a meter and oscilloscope. With a meter and
oscilloscope it should be very quick to troubleshoot. You could try a high school or
college electronics lab.

(* jcl *)

That's convenient :) I happen to be an electrical engineering technology student in college. I actually own my own meter/oscilloscope. How/where should I connect the instruments, and what do I look for?

I am looking at the Hot Rodding the Etherwave
article so all my references will be to that
schematic.

* Start by adjusting the variable inductors as I
mentioned earlier. Also the pitch adjustment
pot should be at it's center position.

* With the DMM verify the +12V and -12V
supplies are operational.

For all of the voltages listed below use
your DMM to verify that the proper voltage is
at the component pin not at the copper
trace that connects to the component pin.
By checking the component pins directly
you will be able to find cold solder joints.
For the resistors and the capacitors use the
assembly layout to pick tha appropriate pin.

Variable Pitch Oscillator

* Verify the +12V is getting to L5, C1, Q2-C.
* Verify that the -12V is connected to R2
* Verify that Q1-E, Q2-E are at -0.6V.

If all of these values are correct you
should see a sine-wave oscillation (~250KHz)
at Q1-C. If you don't check all of the connections for the variable oscillator section.

Fixed Pitch Oscillator

* L6, C5, C8, Q4-C should be connected to +12V
* R6 should be connected -12V
* Q3-E Q4-E should be at -0.6V

You should see the sins-wave oscillation at
Q3-C.

Once both of the pitch oscillators are operational you should be able to tune the
pitch circuit. If the VCA is not operational
you could still tune the pitch oscillator
by connecting the signal at C23 to an amplifier.

*** Be careful of the levels out off of C23 ***

Troubleshooting the volume oscillator is
left as an exercise for the student ;-)

(* jcl *)

Thanks! I'll try that this afternoon and report what happens here. Hopefully that will work. I do have a question in the meantime however. When I try to set the inductors halfway, I can not seem to find where they stop while turning them out (counterclockwise). They seem as though they'll go forever until the slug comes out altogether. Am I missing something?

Do your best to estimate the halfway point.
For inductors it is much more of an art than
a science.

(* jcl *)

Well, Have I ever been delinquent.

An update: I tuned the Etherwave as previously instructed, and VOILA! It works perfectly now.

Thanks for your help, and sorry it took me so long to post back.