Phonoland

Hi,

I'm replacing the selenium full wave rectifier in my Rockola 440 power supply with a silicon one. Can anyone confirm how I should wire the new one?

This is the wiring with the Selenium
http://imageshack.us/photo/my-images/851/selrect1.jpg/


Here is the schematic:
http://imageshack.us/photo/my-images/18/rectschem.jpg/


From what I understand, the WHITE/RED wire (-28VDC) should go to the new rectifier leg marked "-", the RED and RED-BLK should each go to the AC leg connections on the new rectifier. That would mean that the remaining leg on new rectifier would be connected to BLACK (GND) wires?

Can anyone tell me if that is correct?


Thanks,
Robert

Hi Robert,
First question is "Why?"
IMHO, when doing this, it is a MUST to add a fuse to the AC side.
Wiring is simple (unless "special"--your image does not show up)--Plus to plus--neg to neg, and two AC connections, same as the old one ?
Ron Rich

Ron Rich wrote:Hi Robert,
First question is "Why?"
IMHO, when doing this, it is a MUST to add a fuse to the AC side.
Wiring is simple (unless "special"--your image does not show up)--Plus to plus--neg to neg, and two AC connections, same as the old one ?
Ron Rich

Hi Rich,

You should be able to see the pictures now.

I guess it's a bit of preventative maintenance. Most of what I read suggests replacing as it is over 40 years old and when these fail the release nasty somewhat toxic fumes. Does it matter which AC point I add the fuse? Also is it necessary to add an additional load resistor?

Thanks,
Robert

Robert,
I can see it now-- yes the wiring is as you said--but I still would not replace it--yep, they do smell bad, when they go, but they don't go out too often, and with the way that one is fused, I doubt it will ever fail-- (do also remember, that I have zero sense of smell). I would measure the output, under load, and if it is 26 or above, not change it. If you do change it, add the fuse in either AC line. A load resistor is probably not necessary. Ron Rich

Thanks for the information Ron, I really appreciate it. I'll take your advice and stick to the old saying, "If it ain't broke don't fix it!"

flyingpan777 wrote:Thanks for the information Ron, I really appreciate it. I'll take your advice and stick to the old saying, "If it ain't broke don't fix it!"

In general that's Ok, but in cases where the rect provides tube bias I always replace them.

Bought a 201 in April '92. It had cooked coils in stepper and trip, before washing I powered it up with an autotransformer to check the main tran. Any load connected to the minus 25VDC line caused it to drop to 7-8 volts. This had caused the trip and stepper tubes to conduct till they died and damage both stepper and trip coils.

Rob/NYC