Adjusting the speed on a Beogram 6500

After replacing the capacitors, changing the belts and lubricating the mechanical parts, it is crucial to measure and verify that the performance is as expected. I usually do this over a prolonged period using the BeoTac. 

Initial measurements revealed that the turntable was rotating at 31 RPM and 43 RPM. I adjusted the potentiometers accordingly until the BeoTac read the correct speed. The potentiometers are on the main board and are accessible through small holes in the lower left corner of the cabinet. R32 adjusts 45 RPM, and R34 adjusts 33 RPM. 


If you want to replace the potentiometers, please be aware that the datasheet states that R32 is 47kOhm, but on all boards, I've seen they have used a 22kOhm. You can use the CA9V series from tme.eu.

Afterwards, the BeoTac was used to perform speed tests for 33RPM and 45RPM. I've also developed a multi-platform serial plotter for the BeoTac as well. The results are seen below.


Perfect, and ready for a lot of years to come. I've made the source code for the BeoTac and the software available on GitHub, if you'd like to contribute or make it yourself.