Electric Mistriss Range control problems.

[saxtim]

I bought this up at the end of my last Electric Mistress thread, but I think it got a bit lost so I decided to start a new thread.

I've built an Electric Mistress, and after some fiddling (see previous thread a couple of days ago) got it going.  

I still have one probelm though - the range pot does strange things.  When it's set at one extreme the pot works correctly, but if you rotate it, the effected signal cuts out and only dry signal is left.  when this happens there is an audible pop.  Sometimes it pops every second or so and switches between an effected signal and a dry signal (by itself, without moving the pot.)

When the filter matrix swtich is engaged, you can use the range pot to sweep the frequencies manually without difficulty.

Any idea what can be causing this?

thanks

tim

[cjlectronics]

Have you tried using another pot?  Sounds like when the pot is turned the internal wiper is lifting off of the resistive material.  I have seen this happen and I usually replace the pot. You can open the pot and bend the wiper so it is closer to the resistive material but this would only work for an open framed non-sealed potentiometer.

CJ Landry

[saxtim]

Sounds like when the pot is turned the internal wiper is lifting off of the resistive material.

I don't think this is the problem - otherwise I'd expect to have the same problem when the filter matrix swicth is down.  This isn't the case- the range pot works correctly with the filter matrix switch engaged, but incorrectly when it isn't

tim

[saxtim]

Any further suggestions where to look for the problem with this?

tim

[StephenGiles]

This is just acting as a level control on the LFO output, so I think you must have a fairly drastic wrong connection somewhere. Try removing the pot and substituting fixed resistors. If that cures the problem then it is the pot at fault.

[StephenGiles]

This is just acting as a level control on the LFO output, so I think you must have a fairly drastic wrong connection somewhere. Try removing the pot and substituting fixed resistors. If that cures the problem then it is the pot at fault.

[Yuan Han]

I don't have a fix, but I DO have a electric mistress... selfbuilt from GGG too. Has been lying ard for almost 1 1/2 years. Trouble is, there's the delayed signal but just somehow the sweep wasn't going, Last i remembered, the manual sweep worked too.

Never found the problem for it. Its still lying ard.

[saxtim]

[saxtim]

This is just acting as a level control on the LFO output, so I think you must have a fairly drastic wrong connection somewhere. Try removing the pot and substituting fixed resistors. If that cures the problem then it is the pot at fault.

I've just come back to this after a couple of weeks.

I checked for continuity with the schematic between all points and the range control and everthing is correctly hooked up.  As far as I can see the range pot is varying the resistance between pin 6 and 7 from 0 - 100k correct?

Well, when I've got the pot set so there is 0 resistance (continuity between pins 6 and 7) the thing works, it's only when you increase the resistance then the effected signal starts clicking in and out (between a 'dry' sound and the 'wet/blended/flanged' signal.)

I tried subbing the pot with another one which I know is working and still no luck.  It's frustrating cause the thing sounds great when the range control is at 0 resistance (the speed and colour controls work correctly)

Oh and as I mentioned above, when the filter switch is down I can sweep the range manually with the range pot, so it (the range pot) works correctly in that configuration

Any more suggestions on what could be causing this?

tim

[Yuan Han]

I took out the EM and was debugging it the other day. I realised that it WAS the depth pot that was giving weird things too. Like first 3/4 of it it worked fine, beyond that, there was no effect.

Set depth pot to max, and rate pate to about 3/4, resonance pot to full, and proceded to tweak the trimpots. I managed to get a acceptable sound, but when I turned down the resonance pot, the flange was very weak. Proceded to tweak it again. After about 45 mins, it just died. The flange just went away.

I'm using a 18v dc modem power supply with a 12V (or issit 15V) regulator (78L12/5 series). Couldn't get the flange back. Think the BBD' sdead?