Ross Henning
Active Member
Hi Guys,
Well I'm starting a few Pioneer restorations now, including an SX-990. I have a really simple question that I'm actually a bit embarrassed to ask, but I figure it's better to be safe than sorry. I'm installing LEDs in place of the bulbs in this unit. I've ordered white LEDs that should be a direct replacement for the existing incandescent bulbs, but there were three places where I had to do something different. For the dial pointer, there is no socket, and I was able to fit a flat SMD mounted white LED in place of the old wheat bulb along with a resistor to drop the voltage. The other spots are behind the two meters, the sockets for the two bulbs were messed up, and actually shorting out. For those, I fashioned two small Vero boards with SMD LEDs mounted on the Vero along with resistors. The LEDs look great, but because AC fed the original bulbs, I can see the 60 cycle "flash". All of the lamps in the receiver are powered by an 8V secondary off of the main transformer. One side of the 8V AC is tied to chassis ground, and the other side runs through a fuse. I'd like to insert a rectifier and a filter cap to smooth out the power to the LEDs at this point before the power is routed to the selector switch. It's simple enough, but the one thing that really bugs me is that I'm going to have one side of the AC tied to the same ground that will also be the negative for the DC side. That just feels wrong to me, but when I think through it, it seems to me that it would work. I just wanted to run it by the experts before I build my little rectifier circuit. I'm used to the secondary coming off of the transformer with both legs tied to the rectifier and neither to ground.
Well I'm starting a few Pioneer restorations now, including an SX-990. I have a really simple question that I'm actually a bit embarrassed to ask, but I figure it's better to be safe than sorry. I'm installing LEDs in place of the bulbs in this unit. I've ordered white LEDs that should be a direct replacement for the existing incandescent bulbs, but there were three places where I had to do something different. For the dial pointer, there is no socket, and I was able to fit a flat SMD mounted white LED in place of the old wheat bulb along with a resistor to drop the voltage. The other spots are behind the two meters, the sockets for the two bulbs were messed up, and actually shorting out. For those, I fashioned two small Vero boards with SMD LEDs mounted on the Vero along with resistors. The LEDs look great, but because AC fed the original bulbs, I can see the 60 cycle "flash". All of the lamps in the receiver are powered by an 8V secondary off of the main transformer. One side of the 8V AC is tied to chassis ground, and the other side runs through a fuse. I'd like to insert a rectifier and a filter cap to smooth out the power to the LEDs at this point before the power is routed to the selector switch. It's simple enough, but the one thing that really bugs me is that I'm going to have one side of the AC tied to the same ground that will also be the negative for the DC side. That just feels wrong to me, but when I think through it, it seems to me that it would work. I just wanted to run it by the experts before I build my little rectifier circuit. I'm used to the secondary coming off of the transformer with both legs tied to the rectifier and neither to ground.