Capacitor Reforming

Here's a picture of the DAC90A currently on my workbench undergoing reforming of the smoothing capacitors.

 

Reforming is an important process that should always be done before applying power to a set that has been unused for a long time; without it there is a serious risk that damage may result.

The reformer on the left applies a current limited HT voltage to the capacitor, with the applied voltage and leakage current shown on the meters. If all is well, the current will drop to almost nothing after a few minutes, as the capacitor reforms.  

With this set the leakage currents of both sections dropped to around 1mA after about ten minutes, which is an acceptable leakage for capacitors of these values (16uF and 32uF)

There will be more radio recycling blogs coming along soon...

Keep listening!