Both Dual and Papst were located at the same small town at the German Black Forest. I don't know if Dual made their motors themselves or if they bought them from elsewhere. I never found any sign, though, that the TT motors came from elsewhere. In contrary, both the company's name and it's history rooted in an electrical and clockwork driven, double powered »dual« TT motor.
Best regards!
Best regards!
Hey. Hope somebody can answer me here. My EDS 1000 does speed quite a lot every now and then when I turn it on. I then have to turn it off and on a couple of times, then it starts at the correct speed and will run stable until I leave it off for a longer time. This is on 33, on 45 it seems to start in correct speed every time. Any idea what might be the reason?
Now that i have about 40 x ac188 and 10 ac188K measured i feel no worries anymoreYes, if it ain't broken, fix it until it is!
Unless there's some issue with these direct drives, there's no need to do anything beyond the usual maintainance. As said before, those phenolic boards are prone to fail, especially if someone does unneccesary solderings on them. IF the AC188k Germanium transistors may fail some day, one can decide an upgrade to the 721's EDS 1000-2 design.
No need for substituting the venerable 709 opamp by some modern low-noise and high-speed one. You won't hear it!
Best regards!
My old broken uher 4000l also offered me 4 more ac188k. Anyway i dared to replace the original regulator with a motorola 78m12 max 500mA version that trips at 700mA so i should have a little bit more protection.Understanding that these transistors actually work very well in switching mode makes me even happier.
These motors are 40 to 50 years old. The potentiometers are open and not encapsulated and may develop bad contact between wiper and carbon resistive layer. Furthermore, there are a couple of electrolytic capacitors installed which may have dried out over time and lost their nominal capacitance. Also the switches may have seen some corrosion on their contacts over time leading to intermittend contact.