Restoration PSU FP-4

With a rather simple circuit I was able to restore a Yaesu Power Supply Unit FP-4.

The PSU is almost 40 years old and the internal original circuitry was damaged. The transformer, diode bridge and 6800 uF capacitor were still ok.

I found this circuit to replace the existing electronics:

PSU circuitry

Soldered this small circuit on a vero board and installed it in the housing:

Restored PSU

Now the FP-4 PSU is up and running:

Note: PNP Power Transistor MJ2955 may be replaced by MJE2955, TIP2955 or 2N2955.