Nakamichi TA-4A Volume Control Motor

[jjbunn]

My Nakamichi TA-4A works very well, except for one niggling defect: the remote control of the volume does not function.

Voltage is appearing at the motor terminals when the remote control up/down volume is pressed: -6V for down, +6V for up. So that looks fine. I think the motor is dead, as it's open circuit across the terminals which receive those voltages. The motor doesn't work when applying bench supply across those terminals, either.

The motor is the top right cylindrical unit shown in the photo. It is attached to what I assume is a gearbox (rectangular metal box), and the volume/balance pots are just below.

I can't find any motor part number reference in the TA-4A service manual, so I'm a bit stuck. Is it probably a stepper motor of some sort? Any ideas on what might work as a replacement would be most welcome!

 

[pwauk12]

When researching for another potentially dead motorized volume control, I did find some available

try searching for "alps motorized volume control" - digikey and mouser may have some, the are load on EB- the challenge will be finding the right one that fits physically and has the same resistance (250k?)

 

[jjbunn]

Update: I found a used motorized volume control on Ebay for an Onkyo NCVR-2710:


After removing the motor and gearbox assembly from the pot (an easy job), it fitted perfectly into the Nak. Now I have a working remote volume control

 

[AKE13]

Hi jjbunn, congrats, you had a great luck to find matching volume motor. I have issue with housing of volume knob, its broken from inside and kind of loose.

 

[painttoad]

Update: I found a used motorized volume control on Ebay for an Onkyo NCVR-2710:

View attachment 3117833
After removing the motor and gearbox assembly from the pot (an easy job), it fitted perfectly into the Nak. Now I have a working remote volume control

sweet.