Hey all. I recently purchased a nicely preserved PS 8750 turntable, and everything it has gone under a complete restoration before. It works perfectly; however, when I turn the volume of the amplifier high ( higher than what I tend to listen to), I can hear a high-voltage buzzing sound from speakers when the turntable starts spinning. I'm pretty sure that all other components of my Hi-Fi system are totally fine since I tried them with three other turntables, and I never heard this sound with any of those. Again this is only audible in high amplifier volumes when the turntable starts to spin, and when I press the stop button, the buzzing sound disappears immediately. I'm not sure if this is normal or not. Does any other PS 8750 owner/technician have any idea? I assume something related to high-voltage electricity is going on when it starts spinning because the metal unit cover under the platter surrounding the motor also becomes warm too.
Sony PS 8750 high voltage sound. Any ideas?
- Thread starter Ali1376
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- sony ps-8750 turntable
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No. It works pretty smoothly with a steady speed. I switch between three cartridges: 1- Audiotechnica VM540ML 2- Shure V15 type iv 3- Hana SH (high output moving coil)
Thanks for the reply.
Yes. The ground screw is connected securely to the ground screws of the turntable and the receiver. I thought the same at the beginning actually. But if the problem was from grounding, then in that case I should probably hear a hum/buzz sound all the time turntable was powered on, not only during its platter spinning. Shouldn't I? Please correct me if I'm wrong.
flavio81
Turntable technician
That's why I ask if the buzzing stops when the turntable reaches constant speed.
That Sony uses an AC motor. During platter acceleration (from a standstill), the AC motor receives maximum voltage, and thus there might be a noise and perhaps hum might be induced on the cartridge, at very low levels. This should be normal.
I see. Yeah, that makes sense and also justifies the warmness of the metal cover above the motor. By the way, do you think replacing the ground screw with a hard wire connected directly to the turntable would be a good idea?
hd-880
Active Member
Hi, I had the same problem and in the end I discovered that it was due to replacing the Q401 transistor (2SD69), I replaced it once preventively with another TO-3 and it gave me the same problem (voltage noise only when the platter was rotating ). I reinstalled the 2SD69 and the problem was solved, I can even turn the amp up to full volume and it is completely silent now.
Check which transistor is installed in that place and the best thing would be to remove it and test it with a tester outside the equipment.
Check which transistor is installed in that place and the best thing would be to remove it and test it with a tester outside the equipment.