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On Wednesday, August 14, 2019, 8:57:59 PM UTC, Peter Mulhare <peter@...> wrote:

Hello All,

My nanoVNA did not exhibit these problems, and from delivery some weeks ago, has always started whether on? a Power Supply or on Battery alone.

However one thing strikes me when people are talking about this condition is that the 'faulty' ones all seem to have blue LED's in them!? Mine has red LED's.? I know this may sound a bit silly,? but is it due to the type of LED's used in these units the real cause of the problem?? Remembering that different coloured LED's have completely different 'lit' voltages.? This voltage variation could cause faulty operation of the IP5303?

FWIW

73's Pete ZL2iK


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Joe F. KC8RKL
Sent: Thursday, 15 August 2019 06:44
To: [email protected]
Subject: Re: [nanovna-users] NanoVNA does not want to start -solved

Hello all-

I ordered a NanoVNA on eBay and received a black version in a plastic case with mixer shielding and accessories (cables and calibration kit). Mine was like Herman's; it would boot when powered via USB but would not boot via the battery using the ON/OFF switch even when 'fully charged' with the blue charge indicator full-on (without flashing). I read Herman's post and wondered if maybe the IP5303's 'KEY' function state is not guaranteed when leaving the chip factory. So I found a junkbox leaded 10K resistor, bent the leads into a 'U', and touched one end to the battery minus (i.e. IP5303 ground/EPAD) and the other to the IP5303 'KEY' pin (pin 5) for about 1 second. The blue charge indicator came full-on for about 30 seconds, then switched off. But now it boots via battery using the ON/OFF switch! I don't know how long this state will persist- perhaps until the battery discharges completely or is disconnected. This may also have implications for people who received units which functioned normally upon arrival- if their battery goes completely flat, does the IP5303 go into a sleep state requiring the 'KEY' pin to be pulled down 'briefly' via a 10K resistor? I don't know the answer. Anyway, thank you Herman for the fix!

73, Joe F. KC8RKL