An update.
Everything is as it should be and the speed is still slow.
So someone over on Vinyl Engine had mentioned he had built a variable frequency drive using an audio amp a transformer and a sinewave generator for use with a phono he had that was a little slow.
I then realized that I had a functional Bogen CHS-60A amp sitting around collecting dust.
I tried several transformers directly from the amp output with its original output transformer disconnected. I wasn't exactly happy with the results so I then tried a 200 watt 70 volt transformer I had. That didn't produce enough voltage so I disconnected the power wire to the phono circuitry from the 100Vac tap on its internal voltage select transformer and connected it to the 250 Vac tap.
That was fed by the 70 volt transformer.
I was then satisfied with the results as it produced enough AC voltage to power the phono properly.
I then thought about it and realized that idea would be bad unless I changed the power plug on the phono and outlet on the amp (convenience outlet I repurposed for the output of the amp) to something that could not be plugged into a standard outlet as plugging the phono into a standard outlet at 120Vac would put 300Vac on the circuitry and motor of the phono.
So I thought and realized I had the case and mechanism to an AKAI M7 reeel to reel that was from a failed project to connect the tape head directly to a Scott LK-72A tape head input (hum problems) as it could play 1/2 track stereo tapes. I looked and it still had its voltage select transformer installed.
I then rewired the one in the phono to stock configuration and set it for 130 volts.
The voltage select transformer from the AKAI I fed from the 70 volt transformer into its 100 volt tap with the output being taken from the 230 volt tap.
That worked great.
Initially I did my testing with a cellphone app for the audio generator.
61.75Hz is the frequency at which the phono produces exactly 33 1/3 and 45 RPMs.
I then disconnected the link on the amp bridging the reverb in and out as that allows a direct connection to the amp before the tone and volume controls.
Still worked great as the amp section has plenty enough gain.
Decided to recap the amp which required all of 5 electrolytic caps. The cap coupling the amp output to the transformer (Bogen used a low impedance primary) was upped in value to 3300uF.
Main power supply electrolytic was upped to 6800uF.
Power supply diodes were replaced even though they were good as I wanted to be sure the amp was reliable given I'm using it in a way it was not designed to be used.
The other three caps were kept the same value.
I then removed a resistor and cap to effectively bypass the tone controls.
Turns out that the way the Bogen CHS series amps work is they use a transformer with a low impedance primary to provide all the impedance taps and 70 volt tap with the CHS-35 being the base model with no real heatsink and two power transistors. The CHS-60 uses a lower impedance primary a couple circuit changes and a heatsink. The CHS-100 uses an even lower primary impedance, four power transistors, two heatsinks and a few circuit changes.
Before I knew that I knew it would work as I had used a CHS-35 at church for several years where I had modded it to directly drive a pair of 8 ohm speakers in parallel and it ran fine without any complaints. I knew that would work because I had measured the output of the transformer taps and the 4 ohm tap was closest in output voltage to the voltage on the primary so I figured the amp could drive a 4 ohm load.
I installed both transformers in the amp and wired the output to the convenience outlet so the phono an plug right in. That way should a solution to the speed problem ever be found (think some other users of the SR-2050C reported unresolved speed issues as well) I can apply that fix and just plug it right into a standard wall outlet.
Even though the phono is set to 130V input I run the amp to output 120Vac as shown on an older Radio Shack plug in 100-130Vac analog meter for measuring the house line voltage.
I then bought a small function generator on Amazon for around $30 that puts out a sine, square, triangle and sawtooth waveforms which also has a counter and frequency counter which can adjust the frequency in .01Hz increments and will recall whatever settings are stored in save slot 0 upon power up.
That does two things.
Provides the frequency for the amp plus its frequency counter is used with my RCA RP-190 45 player so I can set the video head motor to the right tach frequency for 45 RPMs.
Now I no longer have to use my Radio Shack DMM every time I want to use my 45 player.