From what I remember about pots, it looks like there is no problem here ! Between the ground and one of the connected pin, turning the pot all its course, it goes from 0 ohm to 15.3k between the ground and the other pin, it's 7.7k at an end, 0 ohm in the middle then back to 7.7k at the other end.
It has 4 pins I identified the ground and the two other pins connected to the circuit (the fourth pin is connected to nothing). I measured the resistance of the pitch controller potentiometer. The pitch controller is connected through the 5 pins connector on the bottom of the picture, right top of the big capacitor: The pitch controller board, with the selector and potentiometer : I took two pictures, one of the small pitch controller board, and one of the bigger board to which it's connected.
#Tascam 424 mki discreet transistor how to
It explains how to use the machine, nothing more.
#Tascam 424 mki discreet transistor manual
I have the user manual of the 464, but there seems to be nothing helpful in it. Like a hardened pinch roller or loss of roller tension.Įverything looks clean on that side, and in a pretty good state. I don't know if this machine applies a specific filter when it's on "high speed" if not, it might be a lead to the problem.ĭOn't overlook mechanical as well. Nothing huge, it's just slightly more "muffled" when it's on "high". Something else : strange, but the regular/high speed button does not change pitch, but when I change its position it sounds a bit like there is a change in sound filtering. Now it does not look like it changes much of anything when I turn it. Both seem to be clean.ĭetails that I think might help, about those two pitch controllers : during my first attempt of running the machine after I changed the belt, the pitch potentiometer seemed to work (as far as I remember, cos it was a brief attempt). I dismounted the "pitch control" electronic board, on which are soldered the two pitch controllers : one button to choose between high and regular speed, and a potentiometer for adjustments. So I deduce that it's not a lubrication problem, and that it is not a problem from inside the motor.
I measured the voltage of the capstan motor, and it appears that the variations of speed correspond to variations of voltage. It starts slow, then goes faster for ten seconds or more, then a bit slower etc., with no particular pattern. Now I bump into something else : when I play a tape, the speed (or pitch) is erratic. I had to change the belt that drives the capstan, as it was completely loose and wrapped around its axis. I insist that it litteraly gathered dust. I need some help with my Tascam Portastudio 464 : it gathered dust for a few years in a closet, and now I try to run it again.
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