GroupDIY

General Discussions => Drawing Board => Topic started by: on December 28, 2005, 04:20:37 PM

Title: repairing an amp, wierd potentiometer setup question
Post by: on December 28, 2005, 04:20:37 PM
i am repairing a randall rb200 bass amp.  the control pots for the preamp of the rig are directly mounted to a p.c. board.  they looked to be 16mm (just a guess), and they are all stereo...., but when i look at the p.c. board, the back 3 lugs of the stereo pot on each one is connected to ground, while the other 3 are not, and go to the circuit as expected.  the p.c. board is double sided.  can i just replace the broken pots with regular mono pots?
Title: repairing an amp, wierd potentiometer setup question
Post by: BYacey on December 28, 2005, 04:40:28 PM
Are you sure those lugs aren't just for mounting the pot to the PC board? These prevent cracking the solder joints from vibration.
Title: repairing an amp, wierd potentiometer setup question
Post by: on December 28, 2005, 05:47:54 PM
thanks for the reply.

yeah, the lugs go to what appears to be an actual trace that occupies a large amount of space on one side of the p.c. board, but it is not a support that you would twist on the other end to lend to stability, but rather pins going to a stereo pot with their own wiper.  is this a common practice, or am i missing something here?
Title: repairing an amp, wierd potentiometer setup question
Post by: on December 29, 2005, 01:26:17 PM
bump...  :roll:
Title: repairing an amp, wierd potentiometer setup question
Post by: NewYorkDave on December 29, 2005, 01:28:19 PM
Well, without seeing it for myself and knowing for sure, it sounds to me like they got a good deal on dual pots and simply grounded the unused section. And, as a bonus, the extra terminals add some mechanical stability.
Title: repairing an amp, wierd potentiometer setup question
Post by: on December 29, 2005, 02:52:14 PM
cool, i think im going to go with some mono pots and mount them off of the control panel and bolt the actual board to the chassis.  shouldnt be any problem with having the pots at a greater distance from the board than what it originally was 'eh?