I've used my NanoVNA-H4 periodically for several years. Yesterday I charged it, then upgraded the firmware from NanoVNA-H4-SI_20211230 to NanoVNA-H4-SI_20211230. I re-calibrated and started doing some testing with it apparently working fine. I got distracted for a few minutes, and when I checked the screen was black. I powered it off, then back on, but the display only appeared for a second, then went black.

Since then when I turn it on I see a normal display for approximately one second, then it apparently shuts off.

Things I've tried, none of which have made any difference:
* Charging it, including overnight.
* Powering it on while plugged into a charger or USB port.
* Disconnecting the battery for a while, then reconnecting it.
* Powering it from USB with the battery disconnected.

I wanted to try re-flashing old firmware, but it appears to do the same thing in DFU mode. When I power it on while holding the multifunction switch, I see the following in dmesg on Linux, and dfu-util doesn't see it:

[385834.014786] usb 1-3.4: new full-speed USB device number 39 using xhci_hcd
[385834.104077] usb 1-3.4: New USB device found, idVendor=0483, idProduct=df11, bcdDevice=22.00
[385834.104090] usb 1-3.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[385834.104096] usb 1-3.4: Product: STM32 BOOTLOADER
[385834.104101] usb 1-3.4: Manufacturer: STMicroelectronics
[385834.104105] usb 1-3.4: SerialNumber: 205E33642031
[385835.056995] usb 1-3.4: USB disconnect, device number 39

Any suggestions of other things to try?

Thanks,

Jim

That acts exactly the way I would expect a failed battery to behave, esp. since DFU mode does not eun anything that you flashed . . . Somewhat odd that it won't stay on if plugged in, but the charge circuitry may not provide enough to overcome a failed cell.

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

You battery is likely bad. Lithium based batteries do not like to be deep discharged. It will kill them. The VNAs have a very small but finite current drain when powered off and need to be occasionally maintenance charged if not used for long periods.

On Thu, 24 Oct 2024 07:21:02 -0700
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

I've used my NanoVNA-H4 periodically for several years. Yesterday I charged it, then upgraded the firmware from NanoVNA-H4-SI_20211230 to NanoVNA-H4-SI_20211230. I re-calibrated and started doing some testing with it apparently working fine. I got distracted for a few minutes, and when I checked the screen was black. I powered it off, then back on, but the display only appeared for a second, then went black.

--

73

-Jim
NU0C

I like the battery theory, but I measure 4.1 volts across the battery
terminals with the unit turned on (battery is marked 3.7v) and the device
behaves exactly the same way when plugged into the charger with the battery
disconnected. Neither of those seems consistent with the battery being the
problem.

Jim

On Thu, Oct 24, 2024 at 9:26 PM Jim Shorney via groups.io <jimNU0C=
gmail.com@groups.io> wrote:

You battery is likely bad. Lithium based batteries do not like to be deep
discharged. It will kill them. The VNAs have a very small but finite
current drain when powered off and need to be occasionally maintenance
charged if not used for long periods.

On Thu, 24 Oct 2024 07:21:02 -0700
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

I've used my NanoVNA-H4 periodically for several years. Yesterday I

charged it, then upgraded the firmware from NanoVNA-H4-SI_20211230 to
NanoVNA-H4-SI_20211230. I re-calibrated and started doing some testing with
it apparently working fine. I got distracted for a few minutes, and when I
checked the screen was black. I powered it off, then back on, but the
display only appeared for a second, then went black.


--

73

-Jim
NU0C

I would say do a runtime test on it. That will tell you one way or the other. But do remember to maintenance charge it if you don't use it for a long period of time.

It could also be crud in the power switch. My TinySA was a victim of that. It was highly intermittent. I opened it tonight and after unplugging the battery I vigorously exercised the switch a couple of dozen times. That helped. If the problem comes back I will hit it with some CRC cleaner and maybe DeOxit Gold.


On Thu, 24 Oct 2024 21:39:07 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

I like the battery theory, but I measure 4.1 volts across the battery
terminals with the unit turned on (battery is marked 3.7v) and the device
behaves exactly the same way when plugged into the charger with the battery
disconnected. Neither of those seems consistent with the battery being the
problem.

--

73

-Jim
NU0C

On Thu, Oct 24, 2024 at 10:05 PM Jim Shorney via groups.io <jimNU0C=
gmail.com@groups.io> wrote:

I would say do a runtime test on it. That will tell you one way or the
other. But do remember to maintenance charge it if you don't use it for a
long period of time.

What do you mean by a runtime test? I tried searching but didn't come up
with anything.

Thanks,

Jim

It could also be crud in the power switch. My TinySA was a victim of that.
It was highly intermittent. I opened it tonight and after unplugging the
battery I vigorously exercised the switch a couple of dozen times. That
helped. If the problem comes back I will hit it with some CRC cleaner and
maybe DeOxit Gold.


On Thu, 24 Oct 2024 21:39:07 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

I like the battery theory, but I measure 4.1 volts across the battery
terminals with the unit turned on (battery is marked 3.7v) and the device
behaves exactly the same way when plugged into the charger with the

battery

disconnected. Neither of those seems consistent with the battery being

the

problem.

--

73

-Jim
NU0C

Start from a fresh charge and see how long it takes to run the battery down and turn off. "Runtime test" is easier to type. :)

Recharge it immediately when done.

On Thu, 24 Oct 2024 22:27:17 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

What do you mean by a runtime test? I tried searching but didn't come up
with anything.

--

73

-Jim
NU0C

Currently mine runs for one second after I turn it on. Given that the
battery measures 4.1 volts, do you still think it's a battery issue?

Jim

On Thu, Oct 24, 2024 at 10:34 PM Jim Shorney via groups.io <jimNU0C=
gmail.com@groups.io> wrote:

Start from a fresh charge and see how long it takes to run the battery
down and turn off. "Runtime test" is easier to type. :)

Recharge it immediately when done.

On Thu, 24 Oct 2024 22:27:17 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

What do you mean by a runtime test? I tried searching but didn't come up
with anything.

--

73

-Jim
NU0C

It could measure 4.1V but have high internal resistance. That would cause it to fail under load. I take it that the SA runs OK on USB power?

On Thu, 24 Oct 2024 22:43:17 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

Currently mine runs for one second after I turn it on. Given that the
battery measures 4.1 volts, do you still think it's a battery issue?

Jim

On Thu, Oct 24, 2024 at 10:34 PM Jim Shorney via groups.io <jimNU0C=
gmail.com@groups.io> wrote:

Start from a fresh charge and see how long it takes to run the battery
down and turn off. "Runtime test" is easier to type. :)

Recharge it immediately when done.

On Thu, 24 Oct 2024 22:27:17 -0400
"Jim Ancona N1ADJ via groups.io" <jim@...> wrote:

What do you mean by a runtime test? I tried searching but didn't come up
with anything.

--

73

-Jim
NU0C

--

73

-Jim
NU0C

Take the battery out and run it on USB power.

Roger

On Fri, Oct 25, 2024 at 2:16 AM Roger Need via groups.io <sailtamarack=
yahoo.ca@groups.io> wrote:

Take the battery out and run it on USB power.

I’ve already done that. It makes no difference. I doubt the battery is the
problem because it behaves exactly the same way with or without the battery
connected.

I'm looking for suggestions of other things to try. Thanks.

Here’s my original message, which describes what it’s doing and what I’ve
tried:

I've used my NanoVNA-H4 periodically for several years. Yesterday I charged
it, then upgraded the firmware from NanoVNA-H4-SI_20211230 to
NanoVNA-H4-SI_20211230. I re-calibrated and started doing some testing with
it apparently working fine. I got distracted for a few minutes, and when I
checked the screen was black. I powered it off, then back on, but the
display only appeared for a second, then went black.


Since then when I turn it on I see a normal display for approximately one
second, then it apparently shuts off.


Things I've tried, none of which have made any difference:
* Charging it, including overnight.
* Powering it on while plugged into a charger or USB port.
* Disconnecting the battery for a while, then reconnecting it.
* Powering it from USB with the battery disconnected.


I wanted to try re-flashing old firmware, but it appears to do the same
thing in DFU mode. When I power it on while holding the multifunction
switch, I see the following in dmesg on Linux, and dfu-util doesn't see it:


[385834.014786] usb 1-3.4: new full-speed USB device number 39 using
xhci_hcd
[385834.104077] usb 1-3.4: New USB device found, idVendor=0483,
idProduct=df11, bcdDevice=22.00
[385834.104090] usb 1-3.4: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[385834.104096] usb 1-3.4: Product: STM32 BOOTLOADER
[385834.104101] usb 1-3.4: Manufacturer: STMicroelectronics
[385834.104105] usb 1-3.4: SerialNumber: 205E33642031
[385835.056995] usb 1-3.4: USB disconnect, device number 39


Any suggestions of other things to try?

Roger

It sounds like you may have a component failing on the board, probably in the power supply circuits. I would say to check the electrolytic capacitors, since a failing cap could cause this behavior, but looking at the schematic, it doesn't seem to have any. There are a few 10uF caps that may be worth checking. Other than that, may need to probe with an oscilloscope or meter and see what is happening when it fails.
Since more commonly, failures are mechanical, I would also clean and re-seat all connectors, and see if any of them made a difference.
Schematic: https://github.com/hugen79/NanoVNA-H/blob/master/doc/Schematic_NanoVNA-H4_REV4_3.pdf

And BTW, your original post, and your repeat of it here has an error: you say you reflashed with later firmware, but you gave the same old date code for the new firmware, so we have no idea what firmware you loaded. And most on this list know firmware by its version number rather than build date code. But that is probably not relevant, if the unit is suddenly powering down in DFU mode. The DFU mode bootloader is in ROM on the STM32 microprocessor, you can't brick it with a firmware download - so if it is spontaneously powering off in DFU mode, it must be something in the hardware.

Good luck, Stan

VCC is 4.9 volts, but VDD starts out at about 2 volts when I turn it on and
then drops below 1.7. Is U11 the likely culprit? I guess I could order one
and find out how good my surface mount soldering skills are.

Jim

On Fri, Oct 25, 2024 at 11:07 AM Stan Dye via groups.io <standye=
gmail.com@groups.io> wrote:

It sounds like you may have a component failing on the board, probably in
the power supply circuits. I would say to check the electrolytic
capacitors, since a failing cap could cause this behavior, but looking at
the schematic, it doesn't seem to have any. There are a few 10uF caps that
may be worth checking. Other than that, may need to probe with an
oscilloscope or meter and see what is happening when it fails.
Since more commonly, failures are mechanical, I would also clean and
re-seat all connectors, and see if any of them made a difference.
Schematic:
https://github.com/hugen79/NanoVNA-H/blob/master/doc/Schematic_NanoVNA-H4_REV4_3.pdf

And BTW, your original post, and your repeat of it here has an error: you
say you reflashed with later firmware, but you gave the same old date code
for the new firmware, so we have no idea what firmware you loaded. And
most on this list know firmware by its version number rather than build
date code. But that is probably not relevant, if the unit is suddenly
powering down in DFU mode. The DFU mode bootloader is in ROM on the STM32
microprocessor, you can't brick it with a firmware download - so if it is
spontaneously powering off in DFU mode, it must be something in the
hardware.

Good luck, Stan

I'm in the weeds reading this but what I do to verify a "working"
battery is: charge it up and then put a calculated load across it while
monitoring the battery health. i.e. choose a fixed load like 100ma and
see what happens, yeah, you do the math.

Mike C. Sand Mtn GA

On Sat, Oct 26, 2024 at 04:24 AM, Jim Ancona N1ADJ wrote:

VCC is 4.9 volts, but VDD starts out at about 2 volts when I turn it on and
then drops below 1.7. Is U11 the likely culprit?

It could be U11, or it could be something dragging down the output of U11 (some other failing component presenting a too-high load).
If you can manage it, I would unsolder and lift the output leg of U11 and see if the output of the chip pops back up to 3.3V where it should be.
Another observation to make is to see if any of the chips is getting warm to the touch - if it is pulling down the 3.3V rail, it may be getting hot.
And yes, a VDD of 1.7 is a problem. Maybe the initial 2V+ is enough to turn the processor on such that it can respond a bit, then as VDD goes down, the processor would likely fail.
Good luck troubleshooting.
Stan

I recently purchased one of the little XY-FZ35 5A adjustable electronic load modules to test some battery banks. They are ideal for testing small batteries.

https://www.aliexpress.us/item/2251832767274356.html?gatewayAdapt=glo2usa4itemAdapt

On Sat, 26 Oct 2024 22:40:38 -0400
"Mike C. via groups.io" <mg@...> wrote:

I'm in the weeds reading this but what I do to verify a "working"
battery is: charge it up and then put a calculated load across it while
monitoring the battery health. i.e. choose a fixed load like 100ma and
see what happens, yeah, you do the math.

--

73

-Jim
NU0C

On Sun, Oct 27, 2024 at 01:35 AM, Jim Shorney wrote:

I recently purchased one of the little XY-FZ35 5A adjustable electronic load
modules

I have a similar item and have been pleasantly surprised at how closely its readings track with my calibrated 5-1/2 digit DMM.
I use it a lot when I can't justify dragging out my 400W electronic load. It, too, is surprisingly accurate, as is my USB meter: https://www.amazon.com/gp/product/B08N6XQF91
The amount of good measurement tools available for cheap money these days is a great thing.

73, Don N2VGU

On Sat, Oct 26, 2024 at 11:48 PM, Stan Dye wrote:

It could be U11, or it could be something dragging down the output of U11
(some other failing component presenting a too-high load).

It turns out that my board is version 4.2.1, the scrematic is https://github.com/hugen79/NanoVNA-H/blob/F303_ChibiOS_18/doc/Schematic_NanoVNA-H4_2_1.pdf

If you can manage it, I would unsolder and lift the output leg of U11 and see
if the output of the chip pops back up to 3.3V where it should be.

The regulator is LDO1. I managed to lift pin 5. With no load I measure 3.6 volts. If I put a 33 ohm resistor to ground, the voltage goes to 3.3. So it looks like the regulator is okay. I measure about 3 ohms from VDD to ground, which seems too low.

Another observation to make is to see if any of the chips is getting warm to
the touch - if it is pulling down the 3.3V rail, it may be getting hot.

Not surprisingly, LDO1 gets hot if I leave the power switch on for more than ten or twenty seconds. I can't feel anything else that's very hot though. I tried lifting one pin of C47, but the measured resistance didn't change.

And yes, a VDD of 1.7 is a problem. Maybe the initial 2V+ is enough to turn
the processor on such that it can respond a bit, then as VDD goes down, the
processor would likely fail.

I agree.

I'm running out of ideas. I doubt I could remove the smaller capacitors without breaking them and if one of them was a near-short, I think it would have burned up. I'm happy to hear suggestions of other things to try.

Thanks,

Jim
N1ADJ

The only other idea I have is to remove, clean, and re-seat the display
cable. It has VDD pins next to gnd pins - maybe there is a short, or some
FOD.

On Mon, Oct 28, 2024, 3:23 PM Jim Ancona N1ADJ via groups.io <jim=
anconafamily.com@groups.io> wrote:

On Sat, Oct 26, 2024 at 11:48 PM, Stan Dye wrote:

It could be U11, or it could be something dragging down the output of U11
(some other failing component presenting a too-high load).

It turns out that my board is version 4.2.1, the scrematic is
https://github.com/hugen79/NanoVNA-H/blob/F303_ChibiOS_18/doc/Schematic_NanoVNA-H4_2_1.pdf

If you can manage it, I would unsolder and lift the output leg of U11

and see

if the output of the chip pops back up to 3.3V where it should be.

The regulator is LDO1. I managed to lift pin 5. With no load I measure 3.6
volts. If I put a 33 ohm resistor to ground, the voltage goes to 3.3. So it
looks like the regulator is okay. I measure about 3 ohms from VDD to
ground, which seems too low.

Another observation to make is to see if any of the chips is getting

warm to

the touch - if it is pulling down the 3.3V rail, it may be getting hot.

Not surprisingly, LDO1 gets hot if I leave the power switch on for more
than ten or twenty seconds. I can't feel anything else that's very hot
though. I tried lifting one pin of C47, but the measured resistance didn't
change.

And yes, a VDD of 1.7 is a problem. Maybe the initial 2V+ is enough to

turn

the processor on such that it can respond a bit, then as VDD goes down,

the

processor would likely fail.

I agree.

I'm running out of ideas. I doubt I could remove the smaller capacitors
without breaking them and if one of them was a near-short, I think it would
have burned up. I'm happy to hear suggestions of other things to try.

Thanks,

Jim
N1ADJ