I have a switching power supply for the Digital Receiver, according to which the output voltage is not reasonable. On the PSU PCB board listed 22 V and 3.3 V at the output, but after I measured it using a volt meter, volt meter that shows the number doubled is even more of which are listed on the PSU's PCB board. So that makes 2 Electrolyte Capacitors (220uF/35v) burst / leaking, then I replace both with the same capacity and voltage
I assume there may be errors in the AC (in the primary "Switching Transformer") on the PSU, then I started to check the components one by one, at that part there are two transistors (BU3150 and C6020), both transistors are good , an electrolytic capacitor which large voltage (22uF/450v) good too, then I checked a few other components, such as Diodes, Resisor, capacitor (non-polar), all of the components is good.
Then I checked the DC (in the secondary section "Switching Transformer"), there is an IC 4 pins (B1121 817C) and a non-polar capacitor with high voltage (222 M 400v), which connects the AC and DC good too, no which short linked. there is a transistor in the DC TL431 are also good
the question is, what lead to overvoltage on the output?
please help ..
regards
I assume there may be errors in the AC (in the primary "Switching Transformer") on the PSU, then I started to check the components one by one, at that part there are two transistors (BU3150 and C6020), both transistors are good , an electrolytic capacitor which large voltage (22uF/450v) good too, then I checked a few other components, such as Diodes, Resisor, capacitor (non-polar), all of the components is good.
Then I checked the DC (in the secondary section "Switching Transformer"), there is an IC 4 pins (B1121 817C) and a non-polar capacitor with high voltage (222 M 400v), which connects the AC and DC good too, no which short linked. there is a transistor in the DC TL431 are also good
the question is, what lead to overvoltage on the output?
please help ..
regards
