Ami selenium rectifier replacement

[brianr]

Hi All!  I have an old ami f120 with problems and am planning on replacing the selenium rectifier (I've heard that is wise to do on these old AMIs) with a silicon bridge rectifier.  What's the general thinking on adding an inline fuse on the ac side?  Also what's the best way to test the voltage after installing (I'm not too experienced in electronics unfortunately)?  Thanks for your thoughts.

[jukeboxmarty]

I rarely replace selenium rectifiers unless they show signs of failure. Replacing with a silicone rectifier is an acceptable option, and yes, adding an inline fuse to the AC side is a good idea. When a silicon rectifier fails it tends to short, so you want to protect your transformers. I've heard some people consider fusing each leg of the AC supply for added protection, but I'm thinking that is not necessary. Without checking the schematics I'm pretty sure fuse values of 2 to 3 amps would be adequate.

A volt meter set to the correct range should be able to test the DC side of the rectifier after installation. The voltage will probably be higher than with the selenium rectifier. I don't think the extra voltage should be an issue on this model... but I'm sure someone else will weigh in if that's not correct.

-Marty

[brianr]

Thanks Marty! Very helpful.

[carlos48]

Hi Brinr, I,m not profesional but, what Jukeboxmarty said, is correct. I have a rockola capri 100 and it is working with a new rectifier., due I had to change it, because the selenium one was worn out. I PLaced a 3 amps fuse at the ac said to protect the transformer and the dc parts works of RC works fine. Everything ok in this case.

Carlos.

[brianr]

Thanks Carlos. I am assuming these are slo blo fuses you are using?

[jukeboxmarty]

No real reason for a slo-blow here, I'd stick with standard fast blow fuses.

[carlos48]

That right, I used standard fuses. It works fine.

[brianr]

Thanks Marty, Carlos! Will use standard 3 amp fuse.