Transformer Swap

[Species8472]

Solar_CBB_1.60a

• Species8472
• Nov 13, 2017

This little guy followed me home from a swap meet but he is electrically challenged. The +B winding was open so the last owner patched in that one mounted on the back of the box. All but one domino cap where replaced and it works. The original trans specs are 177v primary, 55v ma40, 63v 40ma and 450v 40ma. I can salvage a trans from an Eico 950B that is the same except the +B is 560v. Would something simple like a power resistor be enough to knock down the voltage to 450v? Do I need to get it to 450v?
It has other issues like there's 60v riding on the on/off switch and there is a mysterious pot (not on the schematic) wired in to the pot used for capacitance readings. I hope solve those issues after I get the power supply squared away. I may even build him a new box.

 

[whoaru99]

Series resistance will limit current, sure, but the amount of voltage drop you get depends on the value of the resistor used and the downstream load. If the downstream load changes so then will the voltage drop.

 

[gadget73]

The amount of current that thing uses is small enough that I doubt the series resistance will affect anything very much. It uses the HV more for leakage testing of caps than anything. Those should all be current limited anyway. Mine is a similar model, but it has seperate jacks for caps and resistors. Probably a very similar circuit.


Power switch should not have any voltage on it. Either you have leakage to the chassis for some reason, or the switch itself has some fault. If this happens to use a pair of caps from power line to chassis, that will cause this. You'll get 1/2 line voltage to chassis. Feel free to ditch them and use a grounded cord. Add a fuse too, I don't think it comes with one. Mine still sports its original cloth wrapped power cord and test leads so I probably ought not talk too much about how to make one of these safe.