Diode upgrade

First off, scuff the surface up with something like a Dremel grinding wheel.  Next, use MORE HEAT, that plate is a big heatsink.  For those jobs, I break out the solder gun, enough heat to do the trick.  Finally, plenty of flux, make sure it's rosin and not acid.

You need a good flux. I have one called Sal-Met that I got at a hamfest about 25 years ago. I don't see it available any longer. I bought a quart which is lasting me. One issue is that it's slightly acidic I think, which makes it work well but is a no-no for electronics. However it does say "Formulated for Electronics". But, I have never had an issue develop from that and I clean the solder joint after making it.

Why not use stud mounted diodes? No need to solder to the plate at all then...

Bill Makel posted:

I have upgraded several dozen postwar TW and LW transformers, clean the plate were the diode is soldered with a wire brush and alcohol but it is often difficult to get good solder flow no matter how clean I get the plate.  How can I get that solder moving.

John is correct more heat and flux is the key BUT too much heat will kill the diode so be sure to use a clip-on aluminum heat sink on the diode lead being soldered.

bmoran4 posted:

Why not use stud mounted diodes? No need to solder to the plate at all then...

Easier and quicker.....

It probably would be helpful to tin the plate where you want to attach the diode and then you can more or less sweat solder the diode to the plate. You'll still want to use a good heat sink.

Good information here will let you know the results when I try Burfle's idea.  Thanks!

Here is another thought: Drill a small hole in the plate for the diode's lead. The inside of the hole will expose fresh metal and should take solder well. (Don't forget the heat sink)

Along the lines of the drilled hole suggestion.  Why not just drill a small hole and use a sheet metal screw to secure it down?

Train Nut posted:

bmoran4 posted:

Why not use stud mounted diodes? No need to solder to the plate at all then...

Easier and quicker.....

 Also, about $0.50 each vs. $8.50 each  unless you buy in bulk. 

Jim

Yes, but the stud mounted diode is much more robust, the diode pictured above is a 6A diode.

 I agree. Nothing beats a stud diode for the old ZW's. They're just a pain in the neck putting in sometimes  Moving all that old stiff wire. And not disturbing the asbestos coated resistor wire.

O GAUGE JIM    said,

 Also, about $0.50 each vs. $8.50 each  unless you buy in bulk. 

 

Order them now before you need them 2ea. for $3.28,  20A 1000v stud mt. I have them in several transformers and they work fine.  Took about two weeks from Hong Kong.   J

https://www.ebay.com/itm/2PCS-...6:g:HfwAAOSwipdaqcnV

I had assumed that these inline diodes were being used where there was no room for a stud diode