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The controller was not powering up from the beginning only when I bypassed the q102 it started. Than my idea was (thanks Stan :)) to trace why I need to do it and found the the micro was probably pulling down the signal probably from the beguining. Probably There was never a blown q102 and sure not a via or track issue. For me was just disappointing because it never worked properly from the first moment because a controller issue.?
I wanted to know why, other wise would be cheaper just order other board, I just spent time, plus parts, shipments, etc. at the end I still don’t know why this pin 88 on the controller was defect, specifically when the power is supplied the rest of the controller seams to work, this puzzles me.

Anyway I live in Germany (Nuernberg) so probably should get a chip from turkey.

73 Azgael

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Everything else seems to work, but no AGC. As a result, there is distortion on loud CW sigs. Yes, it is enabled in the Audio menu. 027 firmware.

Any ideas would be appreciated. Thanks, Dick, K5AND

Alas, the Radtel Speaker-Mic does not appear to be available in the USA from Amazon.

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73, Dave K3DX

On Fri, Apr 4, 2025 at 09:49 PM, Damon wrote:

with IC204 CLK2 into IC501 is 100% @ 3.3V on pin 4. Not sure yet if IC204 or the main mCPU are faulted,

Damon, I wouldn't enjoy the RX. I wouldn't switch on the QMX in this state. Maybe voltage at IC204 is wrong because of IC503 died together with the PA. Best way is to remove IC503 and check output of IC501 and IC502.

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And if the main mCPU would be faulted you couldn't switch on the QMX.

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73 Ludwig

$75 shipped in the Con US

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-Nate

N8BTR

Dan, its a bit risky but I did it with success. You may do it on your own risk!!!

Set the supply to 3.0 V and current limit to 200 mA. Remove all subboards and connect the bench power supply direct to Vdd and GND. I guess the voltage will drop. Check all IC connected to Vdd for temperature. If you find one hot or significant warm, his should be the culprit. If no IC is hot increase the current to 300 mA, maybe later 400 mA but not more. But be sure while increasing the current the voltage is not going over 3.0 V.

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2 Ohm and 0.4 A will produce 320 mW heat, enough to feel it.

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73 Ludwig

One question, reading older posts in this thread the QMX+ was running. But when and why died the controller now?

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73 Ludwig

On Fri, Apr 4, 2025 at 06:33 PM, Azgael wrote:

SO.... now the hard part... disconnect the SPM32 Pin 88 from the LIN_REG_EN! Done.

Good job but bad outcome.

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To replace the STM32 you need one prepared by QRP Labs. If you are located in W you may contact Jeff Moore or else QRP Labs direct.

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73 Ludwig

Nice!

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I'm using an Anker 10000mah power bank and a 9V trigger cable for a QDX. Runs for hours on it, and the power bank gets dual use when traveling.? Been flawless for me, very clean way to power in the field.

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-Nate

N8BTR

My QMX+ died the same way on first start-up smoke test. Perhaps what I have found below may help. You might also want to kill the PA voltage by lifting a wire on L502. ?I did find the known, early manufacturing solder fault on the 5V board. My PA is now crowbarred with IC204 CLK2 into IC501 is 100% @ 3.3V on pin 4. Not sure yet if IC204 or the main mCPU are faulted, more investigation in a couple days. For now, I have the 12v bias on TX turned off in the advanced settings and enjoying the RX.

I should add, I've built 3 this way now. 2 run at reduced voltage (7.5v) feeding my Hardrock 50, and the other is a 40-15m "travel" rig that I run at 9V all the time. No known issues with any of them so far, and I've gotten the travel one pretty warm, and run it pretty hard.

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-Nate

N8BTR

I agree with Tony, I did the grease, too. All good so far, running 9V on a 9V build, no fan.?

Here's a link to a few pictures,? the uploads here get overwritten eventually:

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-Nate

N8BTR

Hi Jack

I see your ICOM microphone has 2 buttons on top !

Would that be an option to wire them in to the 2 on front of QMX+ ??

Or not useful.....

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Cheers

Gert

Hello Everyone, been a while.

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Moderator, If this is against the list rules please delete it.

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The other day I got a message requesting one of those cases I used to sell for the original QCX.

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Normally I just say that I don't make them anymore.? But it got me to thinking, I have an 80 meter QCX kit sitting in a drawer and I'm going to need a case for it.? So I told the gentleman that I would pull out the original files and print one for him.

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So it seems that I am back in the business of making that particular case.? If you have one of the original kit radios maybe it is time to pull it out of the drawer and build it ;)

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Anyway here are links to the videos which I used to send anyone that asked about the case.? I'm still using the original files.

So that's my story and I'm sticking to it.

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w4mhz

Mike

Hi Ludwig

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Yes i now have variable voltage and current supply. Resolution of current limit is 100mA.

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Yes a different result, i was surprised, too. This was measured after trying the new SMPSUs. I haven't knowingly changed anything else?

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Dan

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On Fri, Apr 4, 2025 at 06:57 PM, Dan G7NNZ wrote:

2Ohm (two ohms) gnd->Vdd

Dan, different to Mar 23 (2.3 k) but why? Some element connected to Vdd maybe broken, in the worst case the controller. I will you more info later.

One question; do you have access to a good bench power supply (variable voltage and current limit)?

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73 Ludwig

Hi Jack,

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reminder: this radio booted up and transmitted before I shorted something near the PA.?

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update: new SMPSU boards arrived, I tested before installation, as per the wiki article, and they seem fine.

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I have the SMPSU boards and controls board installed into the main board.?

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With 7.5v, 200mA current-limited supply, I have zero current before pressing power on switch.

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Pressing the power switch briefly I get these on the back of the PCB:

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Board 1:

+12v: 6.0v

Vcc: 0v

adc5v: 0v

pwr_hold: 0.01v

Vin drops to 6.0v?

pwm_5v: 0.01v

pwr_on 0v

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board 2:

Vdd: 0.41

+12: 6.0v

lin_reg_en: 5.0v

pwm_3v3: 0v

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With all sub-boards removed, I'm seeing 1.3kOhm gnd->Vcc and 2Ohm (two ohms) gnd->Vdd, so those measurements have got worse.....

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I then took the SMPSUs out and re-tested, they still pass the tests from the wiki.

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Any ideas where to look?

Cheers

Dan

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To be clear, that spike to 5.7v under worst case 12v supply interruptions would not have damaged anything on the QMX+.

Also, the QMX+ has 470uF on VCC at C107, when I repeat the test with 470uF added the spike is pretty much gone (about 0.1v).

This board would work safely in the QMX+ as originally built.

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Just increasing the VCC inductor from 4.7uH to 10uH did not reduce the spike much, it needed the larger 470uF capacitor.

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Performing these tests where load or supply are interrupted by scraping a wire across a file would likely kill?

a stock QMX, even with the latest firmware.? Also, it would be a difficult test to conduct without risking the STM32F.

This new board has the advantage of being fully testable without being tied to a QMX.

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Designing a robust feedback loop on a switching power supply from scratch is not trivial.

There's a huge range of fault conditions to account for, and tradeoffs to be made between quick response and undesired ringing.

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Jerry, KE7ER

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On Thu, Apr 3, 2025 at 05:26 PM, Jerry Gaffke wrote:

Dear Ludwig

Here follows the next chapters!

I have removed Q102 and Q101 and tested the LIN_REG_EN at the gate of Q101 I got +/-0.6V when pwr button is pressed. So my LIN_REG_EN is being puled down or shorted some where, for sanity I follow the signal pad and I removed the Q110 just in case. I measure again same +/-0.6V.

So now the only connection to the LIN_REG_EN is the STM32, same +/-0.6v on the LIN_REG_EN, seams that the Microcontroler without power is puling the signal down leading it not to start at all.

For sanity I replaced the pull-up resistor R101 and R102 (just in case) same status.?

In my guess I pin pointed this the a problem with the STM32.

SO.... now the hard part... disconnect the SPM32 Pin 88 from the LIN_REG_EN! Done... and confirmed the LIN_REG_EN now measure 12v as VIN. ?

The problem seams to be with the STM32 from the beginning, (So no via issue!!!!Sorry for that one) probably no issue with Q101 and Q102.?

Any way I might be wrong!

Question is what to do next I would like to have the QMX + fully working, some how the STM32 got damaged or came like that.

And thank You so much for the support!

73 Azgael

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