This 20 Amp power supply was brought in because it did not produce enough output and kept blowing fuses.
Typically, when the PSU is making 13.8V DC, then the rectifier is good and it is most likely the voltage regulator that is bad.
This set employed three 2N6057 transistors on the output to regulate the load.
Removing the transistors, was the first step to seeing what was wrong.
Each transistor was tested on my transistor tester and 2 were blown. I had new transistors in stock and began to replace them all. The old transistors had almost no thermal compound seating them to the heat sink and this is most likely why they failed.
The new transistors were seated with new paste and the set screwed back together.
A final test was made with the dummy load to ensure we were getting peak output again. Here the unit is at a low current of 2.71 Amps. A higher load results in more bulbs being lit and an image that the camera can't pick up. However, we had a good 20 amps as expected.
