5 Attachment(s)
Modifying a L-pad for rheostat
Hi,
for my 4430 project I need a pair of 30 Ω rheostats for the treble controls. At first I've found and ordered these. Unfortunately their threaded necks turned out to be very short, they wouldn't reach through the 3/4" baffle board. At the same time I ordered this pair of L-pads for the midrange controls. Their threads are 25 mm long, hence long enough:
Attachment 83607
These L-pads consist of a 8 Ω rheostat that is in series with the driver and works cw, and another 42 Ω one that is in parallel with the xover's high pass output. The latter one works ccw, which is undesirable, and completely shuts off when fully cw, which also doesn't help.
Fortunately my L-pads are very easy to dismantle. Just remove the two screws and they fall apart:
Attachment 83608 Attachment 83609
Note the C clip in the 2nd pic that holds the wiper assembly together. After removing it, the wipers also fall apart:
Attachment 83610
To get cw action for the 42 Ω rheo, both rheo's need to be swapped. Both are soldered at their left handed end to the corrsponding lugs #1 and #3. As the case is made from bakelite, desoldering ain't no problem at all:
Attachment 83611
Next picture in the next posting!