On Monday, November 14, 2016 at 2:48:20 PM UTC-5, wrote:


I'm north of Seattle on Whidbey Island so a visit would be unlikely.
My son has tried to power the thing up and even though parts do work
it won't do any welding. There is no odor of magic smoke so I think
the xmfrs are both OK. I told my son not to power it up any more until
we figure out what's wrong with the thing. The welder has two ranges:
0 to 20 watt seconds and 0 to 200 watt seconds. And my son has uses
for both ranges. Since I sorta talked him into getting a spot welder
like this one I kinda need to make sure we get it up and running.
Thanks for the advice and cap ID.
Eric

Yeah - that is a bit distant, for now. I did get a chance to visit one of the participants herein in his native habitat (central Texas) recently, so, stranger things have happened.

At this point:

a) Focus on the caps. Get them replaced with caps rated, either singly or in combination at 200uF @ 450V minimum. Some basic rules of thumb: Caps in series are additive for capacity, but not for voltage. 10 x 20uF @ 450V (IN PARALLEL) = 200uF @ 450V.

Two caps in series must be calculated, but keeping it very simple, if two 20uF @ 450V are connected in series, the actual capacitance will be 5uF @ 900V. You may see the calculations he https://www.kitronik.co.uk/blog/how-...-and-parallel/

b) Test the tubes by checking the filaments and for any dead shorts internally when cold. A base diagram will tell you which are the filament pins, and then any pin to any pin not internally connected (also given on the base diagram) for shorts.

There are lots of sources for tubes - if you get stuck, let me know and I will root through my spares box. I have 0A2s and 5U4s, most likely in some quantity. As to 2D21s I am not sure, but they are stocked at Antique Electronics Supply (AES) for $5 or so.

Then, your best friend is cleaning anything that can be cleaned without damage. Dust removal, correct lubrication if applicable, rust removal (Beware of steel wool!) and similar.

Best of luck with it - given that you are in the PNW, and, worse, on an island, make sure that you keep the system dry and free of salt. Given the operating parameters of that beast - you DO NOT want stray currents floating around.

Peter Wieck
Melrose Park, PA