This is a follow-up to the other two I repaired a while back part 1 and part 2.
So I got another one of those Gossen Pantam Konstanter T2 33 015 lab power supplies from the 70s with Germanium transistors and selenium rectifiers. Similiarly to the ones I got before the capacitors had leaked quite a bit and needed replacement. Furthermore the drive transistor was broken, so I replaced that one as well.
Unfortunately my supplier didn’t had the large storage capacitor with screw mount anymore I used on the previous repairs (the blue one on the previous posts). So instead I opted to use a normal radial capacitor, on one hand this sucks from an aesthetic point of view but on the other hand its way cheaper regardless.
Protecting the Transformer
Since these are quite old supplies I figured to add a metal-oxide varistor across the transformer windings, in order to protect it against surge spikes. This should reduce the risk of the transformer winding isolation breaking down quite a bit and hopefully makes those supplies work and last longer.
I used TDK B72210S271K101 (S10K275) MOVs and added those to all of my Gossen supplies, two example pictures below.
The leads are just long enough to fit to the terminals.
I soldered them into after the primary side fuse and ensured there is some space/don’t touch the transformer in case they start conducting.
