Chinese diy power supply problem

bertus

Joined Apr 5, 2008
20,650
Hello,

Do you have a list of component values?
Without the values, there is not much to say.
What is the voltage over C3?
That should be higher as the zener voltage.

Bertus
 

bertus

Joined Apr 5, 2008
20,650
Hello,

I already edited the post.
You can not directly link images to those image sites.

Did you replace R2 with an 0.5 Watt (or higher wattage) type, as given in the list?

Bertus
 

dendad

Joined Feb 20, 2016
3,591
Check C2, D5,D6 and C3 for a start.
What is the voltage on C1?
I would change D5 and D6 to 1N400x series diodes anyway.
Those diodes are what I would suspect.
 
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Thread Starter

speedmaster57

Joined Apr 2, 2018
24
c1 has 27v across it, c2 and c3 are fitted right way round and i changed d6 with another diode now it has 2.8v ac across it and d5 has 3.8v ac, and d7 has 0.4v across it. c2 now has 4.5v and c3 has 2.3v sorry for dumb question i am still learning should the -5.1v line be ac because i am getting 0.4v ac on pin 4 of u2
 

bertus

Joined Apr 5, 2008
20,650
Hello,

Check that D7 is fitted the right way round.
In the other direction the mentioned voltage would be possible.

Bertus
 

Thread Starter

speedmaster57

Joined Apr 2, 2018
24
Hello,

Check that D7 is fitted the right way round.
In the other direction the mentioned voltage would be possible.

Bertus
It looks like its fitted the right way round according to silkscreen, can i turn it the other way round could that damage other components
 

EricH45

Joined Apr 2, 2018
1
It looks like its fitted the right way round according to silkscreen, can i turn it the other way round could that damage other components
I have half a dozen of this design (it´s not a chinese..) all working perfectly..
Are all components mounted correctly?
The 4148's and the Z5V1 are very similar and easy to interchange..
 

bertus

Joined Apr 5, 2008
20,650
Hello,

Is the voltage accross C1 correct?
I would expect about 32 Volts.

Are you sure R3 is 220 Ohms?
To me it looks more like 10K.
Take it out and measure it.

Bertus
 
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