Restoring a Power Designs Inc. 6150 power supply
The Power Designs Inc. 6150 power supply is the highest wattage unit in the low voltage single output series. It is a linear power supply designed to output 0 to 60 volts DC in 4 decreasing amperage ranges from 15 to 2 amps as the voltage is increased.
It uses the Power Designs UNIPLY® circuit design (Patent #3,699,352) to accomplish this.
It utilizes dual meters for output voltage and amperage with dual ranges for each meter. The voltage and current limit controls are single turn wire wound potentiometers that also change range settings with the associated meter range switches.
The power supply was a bit dusty inside, but not nearly as bad as several units that I have worked on in the past. I was able to find all the loose hardware inside the enclosure with the exception of one nut. I was worried that a stud mounted diode had possibly been damaged by the loose 110,000 uF 16 volt electrolytic capacitor. But it and the capacitor checked out good.
Most of the restoration involved cleaning and mechanical repairs. I did end up replacing the 15 volt section electrolytic capacitor, but surprisingly the loose 6 volt section capacitor tested good. I will still end up replacing it when I make my next big parts order.
All the electrolytic capacitors on the main board looked great and tested fine in-circuit. I still haven’t decided if there is a need to replace them yet. I am still trying to figure out the manufacture date for this unit, so far my best guess for this units vintage is 1984.
Power Designs 6150 front panel On set to 3.3 volts on 6 volt range with no load
Under full load at the upper voltage in each of the 4 ranges, voltage regulation was better than 0.002% and voltage ripple-noise was less than 0.16 mV P‑P. Current noise was less than 2 mA at a 3 amp load.
I have not yet found an online service manual for this power supply, so I do not know the design specifications. Drop me a comment if you know where I can find one.
I decided to photograph this unit extensively since there was not much in the way of photos and documentation available.
More photos: (click on photo to view at full resolution)
Power Designs 6150 Instruction Manual with Schematics
courtesy of “gto 4ben”