Troubleshooting on Chinese 0-30 voltage dc power supply board

Thread Starter

sanu4011

Joined Mar 2, 2020
8
I have different issue with this same kit , bcz my output voltage can't be adjustable , and also voltage across the r1 is 30-32 vdc and the resistor r1,r2 are heating , then my transistor voltage on 3 terminal is 30volt dc , pls help me
 

AlbertHall

Joined Jun 4, 2014
10,393
If U1, U2, and U3 feel cool then remove and measure C2.
If C2 reads correct, then remove and measure C3.
What is your transformer secondary voltage?
 

Alec_t

Joined Sep 17, 2013
11,641
D7 should be a 5.6V Zener, so it looks like D7 is faulty or the wrong component.
Did you read the paragraph "Attaching a Transformer" in the Manual?
 

AlbertHall

Joined Jun 4, 2014
10,393
D7 should be a 5.6V Zener, so it looks like D7 is faulty or the wrong component.
But the voltage across C3 is also low. Either that negative rail is not being generated correctly or it is overloaded.
Also I can't see how that would drive the opamp outputs to 30V...
 

Thread Starter

sanu4011

Joined Mar 2, 2020
8
Yes I read it , now I found a new resistor with heating up r15 also heating , I so tensed because this board working good in last days I don't know what happened to this
 
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