Selenium Rectifier Question Rockola Jukebox

[63pontiacgp]

Just picked up a Rockola Rhapsody 160 model 408 jukebox and am looking at replacing the selenium rectifier. It was pretty straightforward on my Dynaco ST70 and PAS-3X. This thing looks a bit more complicated, any tips?

Mike

 

[gadget73]

looks like its tapped for multi voltages, or its just multiple segments. Might have to get hold of a schematic to verify whats going on there. Honestly unless its giving you a reason to replace it, I wouldn't bother.

 

[funwithampex]

Looks pretty simply. I see 2 lines from the ac/transformer and then the 2 dc lines. Find the schmatics and find out the voltage and amps...go to radioshack and match it up to a Bridge Rectifiers. The new one will probably be very tiny...I am in the process of changing one out and I will have to place a terminal strip in to hold the rect. I say replace them, get a new one in the circut but this is a huge debate with tons of people. Also they produce a nasty odor when they go. I am replacing mine it is in a preamp...that uses several telefunken 7025's...do I really want to risk a couple hundred dollars in tubes to a 2$ part?

Heres a really good read about them

http://w3hwj.com/index_files/RBSelenium2.pdf

"Selenium rectifiers “age.” That is, as they get older both their forward voltage drop and re- verse leakage current increase, making them less effective. The DC voltages supplied to the associated electronic equipment gradually de- crease causing poor performance."

 

[GordonW]

Is that on main B+? If so, it might be easier to just get a terminal strip, and build a bridge rectifier out of something like four 1N4007s.

Or, if you can find a 1000v rated 1 amp bridge... that should work too. Just hook the transformer leads to the AC lines on the bridge, ground to the (-) lead, and the B+ line to the filter caps to the (+) lead on the bridge...

Regards,
Gordon.

 

[audiofred]

I guess the old saying "if it ain't broke. why fix it?
And replacing the Selenium rect will increase the B+ voltage. And the electronics might not like that

 

[Bobby D.]

There is no such thing as a rectifier with taps, AFAIK. My guess is that there are multiple rectifiers in that stack. The schematic should clear this up. Anyway seleniums should be replaced with SS diodes (I've had good luck without series resistors, but some insist they're needed.) There are no new selenium rectifiers, and the old ones are all past their self life!

Bobby Dipole

 

[Dan ʕ•ᴥ•ʔ]

I have a couple of full wave bridge rectifiers on hand. Their yours for the cost of shipping if you want 'em.

 

[BinaryMike]

In some of the literature I studied recently on selenium rectifiers, there was mention of two distinctly different grades of product. The industrial stuff apparently has a far greater life expectancy than typical consumer electronics products. I suspect that you have little to fear by leaving this selenium bridge rectifier in place.

 

[63pontiacgp]

I had always thought it best to replace them. I have a service manual with schematic on order and will know more about it when it arrives.

Mike