Here I replace the power supply capacitor can in a Dynaco PAS3X, as well as a few signal caps that may help improve sound quality. The overall result being positive, with an improvement in sound clarity and low end definition.
Crosstalk seems to be a common issue with the PASs. I was recently asked to see if I could remedy this on a friend's PAS that I had serviced. I found two things: 1) leads from different inputs are tightly run in parallel together to the selector switch. This looks tidy but causes signal from one input to be induced into the other. Re running these individual wires randomly (it can be done neatly) did help but not completely. 2) The grounds for line level inputs are lifted by a 10 ohm resistor at the inputs. So, although the selector switch shorts the unselected inputs to ground, the 'shorted' inputs are seeing 10 ohms. This will effectivley short high impedance input devices but on something like a cathode follower output with low impedance, it will happily drive signal into a 10 ohm load. Shorting these ground-lift 10 ohm resistors in conjunction with 1) will pretty much take care of the crosstalk. Still, for critcial listening it is best to shut off inputs not being listened to.
Excellent. I'm 69 now and used to love my stereo but now I wouldn't know a good one from bad. Enjoy your ears ( yours are obviously pretty good ) while you can. Great to see somebody maintaining old kit.
