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Ok. I’ve read and read. Many people with similar problem but I still haven’t read the solution as of yet. So I built a QMX 80-20. Like others, I plugged it in and hooked it to my laptop. It was showing up as the flash drive. Wasn’t able to get the firmware loaded for some reason or other. Then…it wouldn’t show up as flash drive anymore. I read to show hidden in device manager and was able to delete everything hoping for a fresh install. No dice. So I launched Putty and it’s showing up but the 3v3 Linear voltage is like 2.56. Did the jumper to make it start up in bootloader mode and SUCCESS! But I still can’t get it to take the firmware? It shows up as an audio device until I jumper the pins. Then it shows as flash drive every time with the single row of blocks. I’m so confused. Anyone have any ideas? I know this is a common thread and probably something silly I’m over looking. Thanks.?

On Wed, Sep 11, 2024 at 11:51 PM, <N4uav@...> wrote:

So I launched Putty and it’s showing up

In this state a firmware is working (see QMX QMX_plus Startup !)

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This means a firmware is working!!!

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You may go to Putty - Diagnostics (where you saw "Linear voltage is like 2.56"), make a screen shot and show it here.

If the 3V3 is in state linear the controller may work but something is wrong. For more Information about this read QMX QMX_plus Startup from the QRP Labs Wiki.

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73 Ludwig

I feel like I’m so close!!

I'm not an expert at reading these screens yet, but it looks to me like the 3V3 SMPS is undervolted, while the 5V SMPS is explicitly declaring an error condition.

Did you build this for the 9V supply you're giving it?

I did build it for 9v. I got scared of the idea of hitting it with 13.8 lol. So I just went across the boards for solder issues again and I actually found a few minor issues that once cleared, dropped the duty max on 3v3 SMPS to 43% so at least there’s that.?

Go back and read the post from Ludwig. ?He has a link to a wiki page to help with these issues.?

The build voltage only impacts the TX output.?

73

Evan

AC9TU

Ok. So the PVM-3V3 is 1.1xxV at PCB #2. I think this is where the problem starts as it’s not letting the SMPS fire up? But what could be causing the low vdc there??

On Thu, Sep 12, 2024 at 02:31 AM, <N4uav@...> wrote:

So the PVM-3V3 is 1.1xxV

At the PWM are pulses. A DC value is the main value. With 1.1xx V main value the SMPS is basicaly working.

I can't read the numbers in the red fields. Could you write these numbers?

If the 3V3 Duty cycle is 42 % (equal to Duty max) then there is an overload.

Please check the SMPS off line (QMX QMX_Plus Power supply test Process).

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73 Ludwig

Understood about the pulses. I got excited a bit prematurely over the duty max numbers. I thought they went down but I was wrong. I am checking the link you sent now. Thank you for taking time to look at this with me!!?

I tried updating the firmware on two different older computers of mine and it never would show up as a drive…

then I connected it to my wife’s newer computer and BAM.. it’s a drive and I updated the firmware.

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It’s probably a simple setting and nothing else on my older computers, but I got lucky when it worked on hers!

I also hope someone has a correct answer instead of ‘keep trying’.

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On Thu, Sep 12, 2024 at 08:56 AM, Alan G4ZFQ wrote:

Older computers? Windows 7 does not see my QDX.

Mike and Alan,

for older OS like Win7 please read QMX QMX plus USB to serial for Win7 and Win8

73 Ludwig

Ludwig, what could be some reasons for overloading the 3V3 SMPS? I had to order a variable voltage supply so the power tests are on hold. Just trying to see if there’s anything I can look at while I wait for Amazon.?

On Thu, Sep 12, 2024 at 04:06 PM, Alan G4ZFQ wrote:

but this does not make the device visible as a removable drive

Yes and so the topic of the Wiki page is (only)

It's not relevant for the USB drive. And b.t.w. I had never a problem to find the USB drive also not when using Win7.

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73 Ludwig

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Alan, you are right. Sorry, maybe I mixed with the problem of N4uav but this should not happen.

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73 Ludwig

My problem was that the firmware was already loaded but I didn’t realize it. I’ve noticed that there are multiple folks that have said they saw the machine show as a flash drive and then it disappears. Once the firmware is loaded, it won’t show up as a flash drive again until you kick off the bootloader. It’s a little confusing until you dive in. My issue is the firmware is there but I’m overloading the 3V3 and can’t get it to switch from linear to SMPS. My variable voltage supply won’t be in until Sunday. I’m impatiently waiting!!!

Ok. Lots of measurements and I KNOW it’s a solder issue. It’s crazy that so many people can have the same issue lol. Anyway, here’s what I’ve got. The 3V3 is what’s having the issue. I applied 9 vac and the LCD come on with blocks. I can still get it into PuTTY but only the diagnostics page. The 3V3 is still on Linear at 2.58v. Duty and Max are equal at 51% with fluctuations but always equal. The 5V board is showing ok now with 5.52 v (but that’s in red) with 77% Max and 65% Duty. All my buttons press and turn and clear all that red.

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PCB2 numbers are as follows:

(VDD is 8.14K ohms with all boards removed)

VDD is 2.961 v

ADC_3V3 is 1.165 v

+12 is 8.8 v

PWM_3V3 is 1.193 v

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PCB1 numbers are:

+12 is 8.81 v

Vcc is 4.96 v

(Vcc is 3.35k ohms with all boards removed and 2.59 with the board installed)

ADC_5V is 2.498 v

PWR_ON is 8.73 v

PWM_5V is 1.52 v

Vin is 8.84 v

PWR_HLD is 2.91 v

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I cleaned all the solder joints up around the J103 and J102 headers. I don’t THINK there’s a cold joint there. I got all the flux I could off of the board and have looked over and over for and bridges. Can’t see any.?
I will say IC101 78m33 on PCB2 is significantly warmer than anything on PCB 1. Not hot per se. Warm. After reading everything I can find, it looks like Vcc ohms could be kinda low. Anybody got any ideas?

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Hans, we could be distant related!! I’m a Summers as well! Haha. Thanks for looking and I’m about as far into troubleshooting as my talents can carry me. I welcome any and all advice. I think I’ve done everything I have been able to determine will put me on the right track.?

On Mon, Sep 16, 2024 at 12:55 AM, <N4uav@...> wrote:

Lots of measurements and I KNOW it’s a solder issue.

At which place?

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Indeed, the problem should be at PCB#2. It looks like the values are from the pin header, right?

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In this state (analog regulator) VDD at the pin header comes from the 78M33. Because different current across D102 and D103 the voltage is a bit below 3.3V.??? 2.96 V is ok here.

We don't see VDD produced by the SMPS. But we have ADC_3V3 produced from the SMPS VDD by the voltage divider R110 and R112. ASSUMING (!) this divider is correct the SMPS VDD is around 2.3 V. In one of your former posts Diagnostics show 2.58 V. I think in this operational state the voltage shown by Diagnostics are a bit higher than real (see VCC = 4.96 V measured by DMM and 5.52 V shown by Diagnostics).

PWM_3V3 = 1.19 V is the mean value from the switching pulses. With 2.9 V for ON (see voltage of the signal PWR_HOLD at ON from the controller) the Duty cycle should be around 41 %. In your former posts 42% and 43% were shown, this fits.

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To find the problem at PCB#2 you should test this board off line (see QMX QMX_Plus Power supply test Process). For step No. 3 reduce the input voltage below 1 V and set a current limit of around 50 mA!!! Doing 3.1 increase the input voltage slowly and check the input current and VDD.

Question: How much input current at which input voltage? Do you have a sudden current increase or is this linear to the voltage?

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73, Ludwig