How to change the output voltage of a switching power supply
Chinese pulse sources in a metal case are very often used by radio amateurs. They have proven their reliability and good price/quality ratio - http://alii.pub/5n14ri
But what if you suddenly need a unit with a different output voltage? Let's say we ordered 24 V, and then realized that we needed 36. Now you will see how easy it is to change the output voltage from a Chinese source.
Conversion of a switching power supply to any voltage 5-40 V
All Chinese pulse generators plus or minus have the same circuit and operating principle. In this example, take a 24 V 10 A unit and increase the output voltage to 36 V. Check before disassembly:
The unit produces 24 V. But to the right of the connection block there is a trimming resistor that allows you to change the output voltage within small limits. Maximum up to 27 V.
We disassemble the metal case.
After opening the lid, the board appears in front of us.
All we need to change is in the upper right corner: the output capacitors and resistors in the feedback circuit.
The resistors in the feedback circuit are located close to the trimming resistor.
Let's continue disassembling the block to get to the bottom of the circuit board. Unscrew the power keys.
Using a soldering iron and a desoldering pump, we solder the original 35 V capacitors.
No, if you need to lower the voltage, then naturally you don’t need to touch them. They need to be replaced if their operating voltage is less.
We solder in capacitors of the same capacity, but for a voltage of 63 V.
To increase the voltage, you need to lower the divider consisting of resistors. Let's replace the 2 kOhm resistor with 1 kOhm.
That's all! Let's check the work.
Using a trimming resistor we will achieve the desired output voltage, namely 36 V.
