Quote:
Originally Posted by erick
I recently came by a Kendrick Dew Controller Model VI. Adverts say it is a pulse width modulation design from 40% to 100%. One control knob, four outlets. Control knob has an on/off switch built in.
When I put the output on the oscilloscope, loaded or unloaded, all I see is 0 volts out in the off position and 12volts out in any control position. "Houston, I think we have a problem here." Just before I drill out the rivets so I can get the lid off and have a look inside, is there anything I am missing here?
I have a home built PWM supply and I swapped that into place instead of the Kendrick and I saw the pulses, under control, as I expected.
Anyone know if I can get a circuit from anywhere? From Kendrick given this is a superseded model?
Thanks
Eric  |
Eric,
I have one suggestion.
If the control is a combination switch/potentiometer then maybe check
the central wiper voltage of the pot with a voltmeter.
In some wiring configurations of pots when the centre wiper goes
'open circuit' after continual use, the voltage across the pot
is as if the controller knob was at the 'top' end.
I hope this makes sense.
By putting one multimeter lead on the centre wiper (2 on the pic), the other on
one of the others(1), turning the knob should see a small
voltage change in a linear or logarithmic scale depending on if
it's an 'A' pot or 'B' pot respectively.
FWIW.
Steve