That 12v 3w lamp near the power transformer is a well established solution to prevent current inrush to the circuit when first turned on. Tube radios had them to protect filaments from bursting before they could heat up properly. They are used here to protect those first generation power transistors Q702 (2N4921) and Q703 (BC149C).
Did you find out what that light bulb @7:35 is for? I just bought a TR-200, and it's got a strange distortion. When I engage the FM, the sound is fine for about a second, and then fades in to a distorted sound. The fading in of the distortion is tied with the light bulb starting to glow. It also has that really faint glow. The light goes out when any other input is selected.
That 12v 3w lamp near the power transformer is a well established solution to prevent current inrush to the circuit when first turned on. Tube radios had them to protect filaments from bursting before they could heat up properly. They are used here to protect those first generation power transistors Q702 (2N4921) and Q703 (BC149C).
Both are NPN on the output. And the colour marked ones are backwards. They have a number.
Thanks Mr Tesla, a very enjoyable repair.
Did you find out what that light bulb @7:35 is for? I just bought a TR-200, and it's got a strange distortion. When I engage the FM, the sound is fine for about a second, and then fades in to a distorted sound. The fading in of the distortion is tied with the light bulb starting to glow. It also has that really faint glow. The light goes out when any other input is selected.
Great work Simon 😁
They sound great! Grow up with having one at our house
What is that light bulb on the board for? Bizarre!
I don't really know, I didn't had the schematic for it, but it can act as a power resistor