Low Voltage Output of Goal Zero Nomad 20 Solar Panel.

Thread Starter

chardc

Joined Aug 2, 2018
4
Hi Everyone.
I have basic knowledge of electricity.
My goal zero nomad 20 solar panel recently stopped working. The cause of this is because an extended usb cable measuring 10ft. or so was used to charge a mobile phone (Samsung S7 Edge). Right now, the LED to indicate Solar power input isn't coming on and the USB output is just about 1V. I also have no warranty to explore manufacture solutions.

Some details (using DMM)
Input is reading 20v
Output is reading 1v for USB, 6.5v for mini solar port, 18v for solar ports.

I tested the inductors (L1 and L2 appear to read less than 1ohm)

I tested the only onboard integrated circuit - 4 paira of pins (the volatage appear to similar to the output ports)

Nothing appears to be damage, but I believe that some form of attenuation or resistance may have caused a short circuit or overheating to damage something.

Can someone advise what other options I have to restore functionality or further tests?
 

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dendad

Joined Feb 20, 2016
3,564
My guess is that main IC is dead.
The board is not that complicated so have a go at tracing the circuit out and posting your results.
Do you have an oscilloscope to look and see if the converter IC is running?
What is the IC as I can't read the number from the photo.
 

Thread Starter

chardc

Joined Aug 2, 2018
4
My guess is that main IC is dead.
The board is not that complicated so have a go at tracing the circuit out and posting your results.
Do you have an oscilloscope to look and see if the converter IC is running?
What is the IC as I can't read the number from the photo.
Hi dendad,

Thanks for your reply and feedback.
Unfortunately, I do not have a oscilloscope and I am unable to get a number off the IC (w. a magnifying glass). I will attempt to trace the circuit as requested and provide feedback.

Regards,
 

Thread Starter

chardc

Joined Aug 2, 2018
4
Okay, I was able to identify the IC as AP1538 / 1623GG.

They're rated at 18V 3A.

I am going to find a replacement, swap it and see if anything changes.

Also, the circuit trace was a lot more complicated - though I grasp the concept after doing some research. I started documenting the components and so forth, but it is a work in progress.
 

dendad

Joined Feb 20, 2016
3,564
Unless you have some experience and a hot air desoldering tool, the AP1538 will be next to impossible to change. It has 2 pads under the IC that must be soldered to the board for heatsinking. I don't think this will be an easy fix.
It may be better ti try to replace the board with something else, like the board from a car phone charger.
 

Thread Starter

chardc

Joined Aug 2, 2018
4
No, unlikely as I tested the extension afterwards and it was functional from the wall adapter.
Thanks for the reply
 

ebp

Joined Feb 8, 2018
2,332
1 volt at the output suggests that something is grossly overloading but not completely short-circuiting the converter and the converter IC has responded accordingly. The typical failure I would expect if the IC is damaged is a short-circuit between input and output.

I don't understand what the inputs and outputs of that board are.

After disconnecting all loads and all input power and allowing at least a few tens of seconds for capacitors to discharge, I would measure the resistance between the circuit common and outputs.The resistance may change as output capacitors charge, but the outputs should all be in the range of at least several hundred ohms after the meter reading stabilizes.

I don't know what the second inductor is for. It isn't part of the core of the switcher but may be part of a radio frequency interference suppression filter. I see a nearby "VOUT+" label. If that were shorted to ground the resistance of the inductor might be sufficient to allow the 1 volt that was measured.

I would check D2 for being shorted. It is probably something to do with polarity protection, but again I don't know what the inputs are.
 
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