I feel like this is something I should have a better understanding of, but I'm not quite finding what I need.
This is the regulated supply for the Philips 212 belt drive turntable.
I had to replace T441 in this circuit. It was a germanium and I only had silicon parts to try. I got it set to the right voltage by increasing R472 but I only get 0.35mV on the output until I probe between ground and TS441 collector with my fluke. So I guess something is just on the threshold of where it wants to work. Is there something else I need to adjust?
I'd just throw in a regulator IC but it seems neither mouser or digikey have any -9V regulators like an LM7909. Or I could just built and insert a new discrete circuit. The original circuit differs from the standard designs I'm finding. R583 would be a zener, D457 would be a resistor, and D458 wouldn't be there.
This is the regulated supply for the Philips 212 belt drive turntable.
I had to replace T441 in this circuit. It was a germanium and I only had silicon parts to try. I got it set to the right voltage by increasing R472 but I only get 0.35mV on the output until I probe between ground and TS441 collector with my fluke. So I guess something is just on the threshold of where it wants to work. Is there something else I need to adjust?
I'd just throw in a regulator IC but it seems neither mouser or digikey have any -9V regulators like an LM7909. Or I could just built and insert a new discrete circuit. The original circuit differs from the standard designs I'm finding. R583 would be a zener, D457 would be a resistor, and D458 wouldn't be there.
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I got the part and installed it. Works great, thanks again! I figured there wasn't much point trying to figure out the original regulator circuit.