The service manual states that the turntable has a supply voltage of 9v, but upon measurement it's sitting at 9.7v. A little high for my tastes... and I'd be fearful of this causing damage over time. It also states that this rail can be adjusted by turning R472, which is a 1k ohm trimpot. It was replaced somewhere down the line with a modern multiturn Bourns type. I started off making small adjustments to it, but this is actually increasing the supply voltage! So I turned it back to as low as it can go (measuring the resistance in-circuit it appears to be at 0 ohms...) and the lowest voltage I've achieved is again 9.7v.
I'm guessing there is an issue elsewhere - but I don't have an idea of where to start to troubleshoot this. If someone could point me in the right direction, it would be greatly appreciated.
Service manual with schematic can be found here (I would add this as an attachment but I'm unsure if this would violate any site rules)
I'm guessing there is an issue elsewhere - but I don't have an idea of where to start to troubleshoot this. If someone could point me in the right direction, it would be greatly appreciated.
Service manual with schematic can be found here (I would add this as an attachment but I'm unsure if this would violate any site rules)