Replacing 5U4GB with solid state recitfier in a SF Deluxe Reverb amp - any mod needed?

[Pixel]

The read is vague. The only indication is in the header description:



I'll guess that "Limiter" is a Zener circuit. But it's only a guess. Also indicated by this header there won't be any significant voltage drop with loading (installing the tubes). And I expect that will be the case even with the transformer DCR since the voltage probably won't sag below the 420V regulation.

My guess is the limiter is an inrush current limiter. No sag means no resistor.

[Helmholtz]

My guess is the limiter is an inrush current limiter. No sag means no resistor.

No need for an inrush current limiter.

[g1]

From the WS-1 web page:
"The WS1 is a solid state rectifier that fits into a standard octal rectifier tube socket. They are built with diodes for rectification and have no sag. This model also has no inrush current limiting. The envelopes are solid hard-drawn copper with a high thermal capacitance that allows a 100% continuous overload condition."
"It is a combination of diodes, power resistors, and other circuitry that emulate the warm-up and operating curve of the tube type rectifier it replaces."
https://www.tedweber.com/ws1/

[Pixel]

I misread the description. The WS-1 is a special case because it isn't meant to emulate a tube rectifier and therefore no warm-up.

[g1]

Yes, it is odd, they claim it is doing some kind of limiting, but do not say whether it is voltage or current or what.

[slidincharlie (Carlo P)]

From the WS-1 web page:
"It is a combination of diodes, power resistors, and other circuitry that emulate the warm-up and operating curve of the tube type rectifier it replaces."
https://www.tedweber.com/ws1/

I am pretty much sure that this particular sentence, even though present in the WS1 Technical Details sheet, refers to all other Weber copper caps, which are meant to replace/emulate each a different rectifier tube. Only the WS1 is a generic no-sag type ideally good to replace ANY tube rectifier, in fact it is half the size of the other copper caps.

[Mars Amp Repair]

I just looked into these because there are no specifics for components data in your post. These seem to be multiple diodes in a single diode case making for multiple standard diode voltage drops (.7V). They do look to be affordable enough but the voltage drop looks to be only about 3V for each unit. To make a meaningful difference it would take several of them and the connections might make implementing that a little clumsy?

I was equally vague above when I mentioned a "string of zeners". So I'll try to clarify. A string of 10V 5W Zeners in series with the center tap of the HV winding (assuming full wave rectification) will drop about 8V per diode. This according to Rob Robinette's site and I think I noticed this also when I tried it. You can get three Zeners on one of those five terminal strips that I like to use sometimes. I think we've all seen them. The ones with the the middle terminal that has a mounting bracket. So skip that terminal. A string of three Zeners would drop 24V. If you need more than that you can use two terminal strips face to face on the same screw mount for seven Zeners staggered across the available terminals. At which time you can choose the voltage drop on the diodes for whatever you need. 10V zeners would drop 56V.

As I recall this thing gets hot so don't mount it near capacitors and leave the leads long on the Zeners, elevated off the terminals so they don't unsolder themselves.

Interesting. As I mentioned, I never actually tried the microwave diodes. The mosfet idea below, albeit requiring heatsinking & some design, sound like a viable solution, too.