1. Disassemble the E-200D. Disassembly instructions are listed on the main page. It
is not necessary to remove any shield covers.
2. There is a PC board on the bottom the chassis. Locate R46.
3. Cut out R46. Cut close to the body of the resistor, so that the old leads are left in
place.
4. Solder a 5K potentiometer to the exposed leads. Ideally, use the same style of
potentiometer as the other ones located around the edge of the PC board. Solder
each end of the pot to an exposed lead, then solder the center wiper to one of the
ends (it does not matter which end).
5. Power up the E-200D and set the MODULATION control to 400 HZ OUT.
6. Connect an oscilloscope to the EXT MOD terminals.
7. Adjust R42 until you get a well-shaped sine wave on the oscilloscope.
(When viewing the back of the generator, R42 is located under the shielded box
along the right-hand edge. There are 2 controls along the right-hand edge, R42 is
the one towards the front of the generator.)
8. Connect a frequency counter to the EXT MOD terminals.
9. Adjust the 5K pot for 1000Hz on the frequency counter.
10. Drill a hole in the bottom of the case so that you can access the potentiometer in
case you need to adjust it in the future.
11. Reassemble the E-200D.
Here's a picture of the pot installed on my unit: