ALPS 50K volume control
- Thread starter EC1
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Alps is still very much in business. Digikey, mouser, and the rest all carry them. You need to know how many pins, the spacing, knob height etc. Thankfully it's pretty standard.
I did try the same search briefly earlier but seems can not find exact match. Mine has 2 x 3 pins with a knurled shaft.
Found this on -bay but not sure it fit or not, 2nd is I heard most of the ALPS pot there are fake.
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JoseHH
Super Member
I believe you may have a 50K linear taper because the B letter in "901B" Currenly the B taper pots are not easy to find. What is wrong with your potentiometer? Often they can be dissasembled and cleaned (scroll to post #9). May be you can keep the original potentiometer. In the worst case, you may be able to get the wafers from the A version you found in Mouser and install them with the knurled shaft. The rotation-volume profile will be different because of the different taper.
There is a shop in france that has 50K A taper potentiometers with knurled shaft. I have no afiliation with that seller. However, you also need to look at the case of the potentiometer. Some audio manufacturers ordered custom versions for their units with a specific shaft lenght. These RK27 potentiometers are constructed by stacking a number of wafer holding shells. In some instances with two-wafers installed in a stack of 3 shells, with the wafers on the rear shell, so that the two shell versions (like the one i linked for instance) would fit on the board but the mounting thread (and most likely the knurled shaft) will not reach the hole in the cabinet. In this case, most likely the knurled shaft will end up being too short to mount the knob. This is why believe that replacing only the wafers is the best solution.
There is a shop in france that has 50K A taper potentiometers with knurled shaft. I have no afiliation with that seller. However, you also need to look at the case of the potentiometer. Some audio manufacturers ordered custom versions for their units with a specific shaft lenght. These RK27 potentiometers are constructed by stacking a number of wafer holding shells. In some instances with two-wafers installed in a stack of 3 shells, with the wafers on the rear shell, so that the two shell versions (like the one i linked for instance) would fit on the board but the mounting thread (and most likely the knurled shaft) will not reach the hole in the cabinet. In this case, most likely the knurled shaft will end up being too short to mount the knob. This is why believe that replacing only the wafers is the best solution.
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JoseHH
Super Member
That is likely to be true. Now that said, the one in tne picture looks genuine. Yet, you need to see if the case of the one you have has 2 shells like the one in the picture from the auction or if it has 3 shells. You can always get the pot in Mouser, dissasemble it to take the wafers from it and install them in yours. This will preserve all the parameters except for the taper.
These are all good information. Thanks a lot.
I still have no luck on rebuilding these pots yet, might need to practice more.
the issue is noise or statics when turning, once it is in position, it is quiet. i can live with it but just thinking if a direct replacement can be acquired it would b nice.
I saw 2 x 3 pins soldered to the board but did not pay attention as 2 or 3 shells.
as far as replacing the wafers from Mouser pot, any particular one I need to get?
I still have no luck on rebuilding these pots yet, might need to practice more.
the issue is noise or statics when turning, once it is in position, it is quiet. i can live with it but just thinking if a direct replacement can be acquired it would b nice.
I saw 2 x 3 pins soldered to the board but did not pay attention as 2 or 3 shells.
as far as replacing the wafers from Mouser pot, any particular one I need to get?
JoseHH
Super Member
Your potentiometer only has 6 pins, so the Alps series model is RK27 and the 50KAX2 that you found in mouser is the best one to get.
Before you embark into the task of dissasembly and wafer swap please take a good look at the potentiometer and see if the one on ebay is an exact match (same shaft and shaft lenght, and 2 shells) If so go with that choice. If you find that wafer swaping is the way to go, please study the videos posted by @Bumpalump. He has uncountable repairs and as far as i saw he shows the most thorough potentiometer maintainance practices. There are several of his videos in his youtube chanel that explain this. Pay attention at the tooling he uses to remove the lock washer on the back. That is one of the key tasks. There is also a proper alignment to match the volume on the left and right channels.
Before you embark into the task of dissasembly and wafer swap please take a good look at the potentiometer and see if the one on ebay is an exact match (same shaft and shaft lenght, and 2 shells) If so go with that choice. If you find that wafer swaping is the way to go, please study the videos posted by @Bumpalump. He has uncountable repairs and as far as i saw he shows the most thorough potentiometer maintainance practices. There are several of his videos in his youtube chanel that explain this. Pay attention at the tooling he uses to remove the lock washer on the back. That is one of the key tasks. There is also a proper alignment to match the volume on the left and right channels.
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