Hello all,
As many of you are having problems with the same diy kit, im having the same problems.

Im using a 24v 3 Am AC as input.

From the troubleshooting thread that i read, non of the measurments are correct with my kit.

1st indication is that LED is constantly active.
With 10k pontesiometers i can change output voltage but anti clock wise is 20v and clockwise 1.1
When i try to use output to a lamp 12v nothing happens.

I have triple checked material installed and its correct. also i have even change some of the part with new one, because there was wrong.



Point A : is 33.5V instead of 32.5V
Point B: instead of -5.6v i have 326mV
Point C: is 24V Correct

Can somebody help to fix this problem.

 

hi tote,
Welcome to AAC.
Do you have a circuit diagram as part of the kit that you could post.?
I guess you have confirmed the 5V1 Zener is a zener and is the correct way around.?
E

 

Point A is fine. I agree with Eric, either the zener is the wrong way round or its not a zener, is the most likely cause but there could be other issues.

Can you post a schematic or a link to it, and maybe a photo of your board alongside the example above.

 

First of all thank you for your kind reply.

Scematic :


Board



Part with the zener for which i have double checked polarity and name.



Also the pdf file from which im making all measurments

 

Measure volts to ground from at bottom end of R3 - 2nd resistor from left at bottom left of board. Measure volts at bottom end of D5, the diode next to it. Report back.

 

hi tote,
Downloaded your documentation, will check thru it, let you know what I find.
Did you confirm that D7 is in fact 5.1V Zener Diode.?

E

 

hi tote,
Some of these soldered joints look 'dry' use some flux and resolder ALL the joints in this image.

E

 

Measure volts to ground from at bottom end of R3 - 2nd resistor from left at bottom left of board. Measure volts at bottom end of D5, the diode next to it. Report back.

Hi Irvin.
Bottom R3 5.3V
Diode D5 2.4V

 

hi tote,
Some of these soldered joints look 'dry' use some flux and resolder ALL the joints in this image.

E
View attachment 211125

.. Hi Eric Will do now, thanks for noticing that

 

Remeasure after resoldering, with your black lead on ground. Both voltages should be negative with respect to ground. Ground is the right hand end of the two big diode above next to the word 'LED'.

 

Just run a LTSpice on that bit - those values are exactly right if the zener diode is in back to front, though I agree the pictures suggest otherwise...

Right


Wrong

 

Found an image of back of board showing how everything connected

If its not the wrong way round, then it looks like that Zener is either fried or isn't a zener....

 

hi Irving,
A small point C3 is the wrong way around.
Please post your asc file.
E

 

Good catch Eric, doesn't impact simulation much...



Here's the file...

 

Hello all, should i change zener diode with the same value or to try a diffrent one "?

 

try another of the same... maybe that first one was faulty..

 

hi tote,
A 5V1 Zener should be used to replace the suspect zener.

E

 

@ericgibbs Did you mean 5.1v for a reason? The original part is a 5.6v device...

 

hi I,
The PCB image silkscreen shows 5V1.?
E

 

one strange thing is at the positive of the capacitor down left but on the right side, im measuring 0 Volts, i have already changed the capacitor but nothing changed.
The positive side is the input of the zener 5V1