Issue with low voltage circuit

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3 years 1 month ago #7641 by fas66
I purchased the modular nixie clock with WIFI. I have begun to assemble it and am having the following problem:

I completed the low voltage section with following result:

When applying the power source (9 v, 0.5A), the led will not light and I do not show any voltage between any GND test point and VCC test point.
I have 9v between the GND test point and rear pin of the power jack
I have 9v between VCC and rear pin of power jack.
No voltage between GND and VCC at 4 pin connector.
If I touch probe to both VCC and VIN on 4 pin connector with power supply hooked up, the LED lights up.

Both 220uf caps have correct polarity
The little 100nf cap (pancake cap marked 104) had no polarity markings and I don’t believe it makes a difference with those little caps, at least it didn’t on the last clock I built.
The inductor was not as pictured, it was a dumbbell shaped cylindrical inductor not the 330 marked inductor. There were inductors of that type and I used the smaller one here after researching what I had. Polarity should not be an issue with the inductor.

Can you provide some guidance or point to potential problems or whether or not I have a bad component. All components are hooked up correctly as far as I can tell. D1 and D3 are installed at the correct points and polarity. I am just getting in to electronics and do not have a lot of experience with circuits and components, but I did successfully complete a working nixie clock using IV-11 tubes. That one had horrible instructions, basically just some bad pictures. Your instructions are much better.

Do I need a bigger power supply (> 1.0 amp)?

My kit shows version 46 but I am using the version 45 manual.

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3 years 1 month ago #7652 by Ian
Replied by Ian on topic Issue with low voltage circuit
The 100nF cap is not polarised.

The 33uF inductor for the buck regulator could be an SMD device with no leads on it (eariler versions) or a traditional through hole device (later versions). It is not ploarised.

The differences between 45 and 46 are all software, there are no differences in the hardware. The v45 manual is fine.

You might need a stronger power supply later, but right now we don't need to think about that.

If you can add a photo of the top of the board in the "LV corner", I can check for problems.

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3 years 1 month ago #7661 by fas66
Thank you, I'll get a picture on here as soon as I figure out how to add one, otherwise I'll send it to the e-mail address.

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3 years 4 weeks ago #7684 by fas66
I installed a new voltage regulator (LM2596T). This had no effect, the same issues exist. I also replaced the power supply with a 9v, 2A unit. again no change.

I took some voltage readings at the inputs and outputs of the diodes and found the following.

With power supply hooked up, I have the following readings at the diode:

From 9v output to D1 input pin: 0.0 VDC
From 9v output to D1 output pin: 243 millivolts dc

From 9v output to D3 input pin: 9.85 VDC
From 9v output to D1 input pin: 9.78 VDC

From D1 input to GND test point: 9.83 VDC
From D1 output to GND test point: 0.0 VDC

From D3 input to GND test point: 0.0 VDC
From D3 output to GND test point: 0.0 VDC

From D1 input to D3 input: 9.83 VDC

I also have new diodes coming, probably today, so I'll replace both of them and see what happens.


Fred
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3 years 4 weeks ago #7685 by fas66
I noticed on the picture of the low voltage circuit in the manual that D3 was not installed. SV1 was also not installed. will this make a difference? I have both D1 and D3 installed.

Fred

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3 years 3 weeks ago #7703 by Ian
Replied by Ian on topic Issue with low voltage circuit
Can you check the results at D1 again, they don't look right. It looks like D1 is open circuit.

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