"Franc Zabkar" wrote in message
...
On Fri, 8 Aug 2008 17:52:49 -0700, (Dave Platt)
put finger to keyboard and composed:
The rotary encoder in my Wavetek 75 arbitrary waveform generator is
physically broken, and it's impossible to hook anything up to the broken
legs to probe the specs.
I'm totally new to encoders and I'd appreciate if anybody can offer any
advice on finding a suitable replacement. I couldn't find the service
manual for Wavetek 75, so all the information I have is the encoder
itself:
http://www.stanford.edu/~wonghoi/DC/...coderFront.png
http://www.stanford.edu/~wonghoi/DC/...ncoderBack.png
http://www.stanford.edu/~wonghoi/DC/...EncoderCap.png
Hmmm.
Based on the photos, it appears to be a mechanical rotary encoder,
with a two-bit quadrature output and a common terminal. By my count
there are 13 or 14 contact fingers per output per quarter-revolution
of the control... this would allow for 50-some pulses per revolution
for each of the two channels, or around 200 counts per revolution if
you're doing the usual sort of quadrature decoding.
The cap is stamped with a "50". Could that be the number of pulses?
BTW, that's a Matsu****a logo. I can't guess at what "6L" might mean,
though. Could it be a part number series?
FWIW, there are some Wavetek manuals he
ftp://bama.sbc.edu/downloads/wavetek/
Would this wavegen have a similar encoder?
ftp://bama.sbc.edu/downloads/wavetek/275/
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
I misinterpreted the image of the broken rotary encoder that the OP posted. I
saw the broken part as the codewheel, not the wiper part with the contacts
attached. Apologies.
I forgot that the subject line mentioned the model 23. Here is a link to the
manual for the model 23:
http://www.ko4bb.com/cgi-bin/manuals...tion_Generator.
It gives you a pretty good description of the encoder operation, and a picture
of the code wheel. Not much else about the encoder itself, though. The
description of the encoder in the model 23 manual doesn't seem to fit the
images of the model 75 encoder.
The only info given about it in the parts list is the Wavetek part number, which
is 5109-00-0026. Wavetek is listed as the manufacturer.
The schematic shows two contacts in the encoder. That would seem to agree with
the OP's thinking that it is a 2-bit encoder. The model 23 manual indicates
that the encoder outputs 50 pulses per revolution.
Since there doesn't seem to be an indexing contact on the wheel, I think you
could use an encoder with a lower number of steps per rev without any problem
(electrically). It might, however, make the adjustment less sensitive due to
the reduced resolution of the encoder. You'd have to make more turns of the
knob with the lower resolution encoder.
Find one at Mouser or Digikey with the appropriate physical characteristics and
highest resolution and give it a try. Nothing to lose at this point.
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)
Experience: What you get when you don't get what you want