Re: How to clean oxidised QMX soldering pads
Use a rough kitchen towel like cloth to polish it a bit?
If still no good just swap to a solder wire with slightly more active (medium agressive) flux ( the board will need cleaning after assembly but the soldering will work fine on most good, difficult and even poor surfaces )?
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Re: New QMX build.. something not right.. Display squares and STM chip hot
Hello,
how much current into the QMX at which voltage?
Is the display backlight on?
You could load the firmware again (forcing the QMX with hardware connection, see manual).
73, Ludwig
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Hello Jeff,
how much current into the QMX and which voltage?
73, Ludwig
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Maybe its the same like described here but much stronger due to the parameter settings (Menu - Audio - Sidetone volume and abs/rel)?
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Re: How to clean oxidised QMX soldering pads
Hi Matt,
IMHO oxidised soldering pads after a few months and storing the PCB in a normal enviroment are strange.
There is a real difference solder 2 layer PCB an 6 layer PCB.
Here is my experience.
For 2 layer PCB: holding the iron tip on the pad and the wire tin will flow fast to both.
For 6 layer PCB: tin will flow fast to the wire and later to the pad. It takes some time, often some seconds to heat up the pad enaugh. Depending on the kind and amount of flux this could be gone in these some seconds and lacks for the pad. This looks like the pad is oxidised and refuse the tin.
Could you tell something about yor solder tools?
Type of solder iron, shape of the tip, power, temperature, type, brand and diameter of tin
73, Ludwig
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Re: #qmx not powering up after firmware installation
#qmx
Alex, some comments...
I agree with Luswig that the transformer wire solder joints shown?in your photo look like they need to be redone. It looks like a case of insufficient enamel removal from the wires, a very common problem.
You measured 2.41 volts at all points around T401. That is proper and good. It is unlikely that IC402 has failed. Failure of that chip most often drags that voltage up or down quite substantially.
Your receive current is excessive, Is IC407 getting warm/hot? That chip is usually the first victim of an overvoltage event on the 5V distribution. If it?is completely dysfunctional, you will hear nothing.
Do you have access to an oscilloscope? ... how about a low power signal source (Sig gen, NanoVNA, nearby transmitter?)
Because you apparently can transmit, it would appear that at least part of the clock gen chip IC204 is working (CLK2). It would be good to scope and observe that the other two outputs (CLK0, CLK1) are producing outputs correctly.?
If that looks good, set the QMX receiver to a known frequency and set a signal source about 1 KHz higher?in frequency. Let QMX pick up the signal source via very loose coupling to QMX' antenna input. Yes, I know you can't hear the resulting?beat note. That's where the scope comes in. Look at the op-amp outputs of IC405A and IC406A (pin 1 on each chip). You?should see a pair of sine waves at about 13KHz and with a 90 degree phase difference. You should see the same at pin 7 of each chip.
If you see these sine waves?it pretty much confirms that your receiver chain is working properly from the antenna input to the op-amp outputs. The problem then is most likely a failed IC407.
GL with your trouble-shooting...JZ KJ4A
On Mon, Apr 8, 2024 at 9:49?AM < DH8WN@...> wrote: Hi Alex
On Mon, Apr 8, 2024 at 01:45 PM, @Ludwig_DH8WN wrote:
It reminds me of an thread some time ago with a similar situation
Here is the link.
Like described I would desolder T401 to IC402 and connect a capacitor to the open end of T401. With some meters wire connected to the other side of the capacitor (antenna) you could check the Rx. FT-8 frequencies are a good source for signals.
73, Ludwig
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How to clean oxidised QMX soldering pads
Hi guys,
I just finished my low band QMX and everything works fine. QSOs all over Europe, CW sidetone clicks acceptable. ?The hardest problem during building the kit for me was that the soldering pads seemed to be slightly oxidised during some months between delivery and built. Some other OMs reported the same problem. Is there any advice for a non professional like me how to ?clean¡° the PCB before building the next kit?
Thanks and 73
Matthias DL5MAY
--
Matze
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On Sun, Apr 7, 2024 at 04:00 PM, Roy - KI0ER wrote:
Since SOTA is already taken, we'll need to start BOTA (Boats On The Air)!?
?
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Hello everyone,
I recently built a QMX and I'm having some trouble getting it to run. I loaded the firmware, but it doesn't appear to get through the application initialization.??
I probed the PWM lines on the supply converter boards and there's never any activity, as if it's not getting to the point where it tries to start them up.
If I force the loader with the aux2 jumper, there is now an eeprom file in the drive, indicating it was running at some point.
Sorry if this was covered?already.. also wondering why my supply board #1 doesn't look like the photos.? It has a large SMBJ package next to C107 instead of the sot23 and chip resistors.. so I don't have a component placement diagram to identify some of the parts.
Any suggestions for next steps?
Thanks
Jeff
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Any help is appreciated. Just built a qmx and tuned.? Everything seems to work correctly. My problem is when transmitting, I'm getting an annoying loud tone ( sounds like someone is hitting a wood table) on every dit and dah. Seems to be all the same tone and volume no matter what I set the transmitting tone volume. It only happens on transmitting on every band. Qmx is 80m-20m. Not sure what to do
Thanks in advance
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Re: I let the smoke out¡
...Or perhaps you have not correctly implemented the battery feed experiment.
Your question about the impact of the modulator while doing the low voltage test suggests that maybe you don't correctly understand the setup, as the modulator would be completely out of the picture in a correctly set up test. The wire from L502 would have been disconnected from Q507 and diverted to a resistor and then a battery.
Two things:
Send a photo of your test hookups at the board and battery.
Send a scope trace taken at the drains of the BS170s.
JZ
Mike,
To be honest, none of those screens look as what I would have expected and I have no idea what the problem might be. Probe grounding problem?
JZ
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Re: I let the smoke out¡
Mike,
To be honest, none of those screens look as what I would have expected and I have no idea what the problem might be. Probe grounding problem?
JZ
On Mon, Apr 8, 2024, 8:27?PM Michael LaBlanc < mlablan1@...> wrote: JZ,
Thank you very much for the detailed explanation of the RF Envelope Shaping circuit.? I am still digesting the full explanation and will do some followup self leaning on YouTube to get up to speed on some of these concepts.? In the short term I do have one follow up question regarding the troubleshooting strategy of introducing a low DC voltage into the downstream PA circuit.? If this piece of the design "modulates the voltage to the PA transistors" and I introduce a static 1.6VDC, how will that impact the interpretation of the resultant downstream signals?
Per your recommendation I did put a 10 ohm resistor at the end of L502 (the other end attached to the tap of T501) and wired in a AA battery which gave me 1.6 VDC.
Attached are 5 pictures of the signals measured in the transmit state:
1 - T501 Secondary Winding
2 - D508 Cathode
3 - D511 Anode
4 - D509 Cathode
5 - D510 Cathode
Without much depth of knowledge in this area, it seems to me that the signal at T501 and D508 look OK, but I am losing a lot of amplitude at D511.? Also, the signal at D511 is hardly a smooth sine wave.? Can you comment on if you think this is expected?
I believe the two signals at D509 and D510 to be basically noise.? I think this is expected since I am transmitting on 20M which should activate LPF 0 and keep LPF 1 and LPF 2 deactivated.
Are there any other points I should try to measure with this setup?
My idea for my next step is to carefully cut the 2 legs of Q507 so that I can attach a component tester on this device to see if I can prove a failed part.? I will attempt to cut the legs in such a way that I can solder them back together if this part proves to be OK.? I don't want to take this step until I fully explore any additional opportunities with the test setup mentioned above.
Thanks so much for your continued support on this troubleshooting journey.? It certainly is challenging, but I am learning A LOT through this process. ?
Mike
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Re: I let the smoke out¡
JZ,
Thank you very much for the detailed explanation of the RF Envelope Shaping circuit.? I am still digesting the full explanation and will do some followup self leaning on YouTube to get up to speed on some of these concepts.? In the short term I do have one follow up question regarding the troubleshooting strategy of introducing a low DC voltage into the downstream PA circuit.? If this piece of the design "modulates the voltage to the PA transistors" and I introduce a static 1.6VDC, how will that impact the interpretation of the resultant downstream signals?
Per your recommendation I did put a 10 ohm resistor at the end of L502 (the other end attached to the tap of T501) and wired in a AA battery which gave me 1.6 VDC.
Attached are 5 pictures of the signals measured in the transmit state:
1 - T501 Secondary Winding
2 - D508 Cathode
3 - D511 Anode
4 - D509 Cathode
5 - D510 Cathode
Without much depth of knowledge in this area, it seems to me that the signal at T501 and D508 look OK, but I am losing a lot of amplitude at D511.? Also, the signal at D511 is hardly a smooth sine wave.? Can you comment on if you think this is expected?
I believe the two signals at D509 and D510 to be basically noise.? I think this is expected since I am transmitting on 20M which should activate LPF 0 and keep LPF 1 and LPF 2 deactivated.
Are there any other points I should try to measure with this setup?
My idea for my next step is to carefully cut the 2 legs of Q507 so that I can attach a component tester on this device to see if I can prove a failed part.? I will attempt to cut the legs in such a way that I can solder them back together if this part proves to be OK.? I don't want to take this step until I fully explore any additional opportunities with the test setup mentioned above.
Thanks so much for your continued support on this troubleshooting journey.? It certainly is challenging, but I am learning A LOT through this process. ?
Mike
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New QMX build.. something not right.. Display squares and STM chip hot
Hi guys. Rev 3 build for high bands.
I was able to power on and load a firmware file.
After the reboot I now get squares on the display and the STM32 chip gets progressively warmer.
I have checked connections of display, and power boards and re-soldered both.
Display pot checked and working.
I suspect I may have killed the STM32 chip during the build, or perhaps one of the components around it causing some sort of short.
As I was able to load the firmware, I also tried connecting to the serial terminal. This is the output display I get... which indicates to me that _something_ is working.? Any clues?
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Re: Pushbuttons are not responding
OK. I'll check that and report out when I get back to it tomorrow morning.? Thanks all for the help. This one really has me a bit befuddled.
Wayne
On Mon, Apr 8, 2024 at 2:22?PM mike/w1mt < w1mt.qrp@...> wrote: Weird that the Tune encoder button is working but the two pushbuttons
are not. They use the same divider resistor (R211). I suppose you
could try checking the voltage at pin 6 while powered and pressing
each button. Figuring what each button should create is simply a
voltage divider calculation, or measure it with a known good board and
compare with the bad control board. If you can, measure it on the main
board pin 6 for that connector.
-mike/w1mt
On Mon, Apr 8, 2024 at 2:11?PM Wayne Greene <wayne.greene489@...> wrote:
>
> Hey, Ron. The encoders are working. I just checked R301 and R302. R301 is reading 3.3k and R302 is reading 6.8k.
>
> Wayne
>
> On Mon, Apr 8, 2024, 14:00 Ronald Taylor <wa7gil@...> wrote:
>>
>> Wayne, are the encoder buttons working? If they are also not working you should check for continuity from the ground side of any of the buttons back to a main board ground point. It's probably a good idea to check continuity to the main board ground from each of the 4 buttons anyway. If it's just the two little push buttons, then you might also check to see if resistors R301 and R302 are present and undamaged. Good luck ... Ron
>>
>> On Mon, Apr 8, 2024 at 10:52?AM Wayne Greene <wayne.greene489@...> wrote:
>>>
>>> Hey, Chris. I could see how that can happen, for sure. I have the headers installed correctly. The encoders are working, so I'm taking that to indicate the control board header is installed correctly, anyway.
>>>
>>> Wayne
>
>
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Re: Pushbuttons are not responding
Weird that the Tune encoder button is working but the two pushbuttons
are not. They use the same divider resistor (R211). I suppose you
could try checking the voltage at pin 6 while powered and pressing
each button. Figuring what each button should create is simply a
voltage divider calculation, or measure it with a known good board and
compare with the bad control board. If you can, measure it on the main
board pin 6 for that connector.
-mike/w1mt
toggle quoted message
Show quoted text
On Mon, Apr 8, 2024 at 2:11?PM Wayne Greene <wayne.greene489@...> wrote:
Hey, Ron. The encoders are working. I just checked R301 and R302. R301 is reading 3.3k and R302 is reading 6.8k.
Wayne
On Mon, Apr 8, 2024, 14:00 Ronald Taylor <wa7gil@...> wrote:
Wayne, are the encoder buttons working? If they are also not working you should check for continuity from the ground side of any of the buttons back to a main board ground point. It's probably a good idea to check continuity to the main board ground from each of the 4 buttons anyway. If it's just the two little push buttons, then you might also check to see if resistors R301 and R302 are present and undamaged. Good luck ... Ron
On Mon, Apr 8, 2024 at 10:52?AM Wayne Greene <wayne.greene489@...> wrote:
Hey, Chris. I could see how that can happen, for sure. I have the headers installed correctly. The encoders are working, so I'm taking that to indicate the control board header is installed correctly, anyway.
Wayne
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Re: Pushbuttons are not responding
Hey, Ron. The encoders are working. I just checked R301 and R302. R301 is reading 3.3k and R302 is reading 6.8k.?
Wayne
On Mon, Apr 8, 2024, 14:00 Ronald Taylor < wa7gil@...> wrote: Wayne, are the encoder buttons working? If they are also not working you should check for continuity from the ground side of any of the buttons?back to a main board ground point. It's probably a good idea to check continuity to the main board ground from each of the 4 buttons anyway. If it's just the two little push buttons, then you might also check to see if resistors R301 and R302 are present and undamaged. Good luck ... Ron
Hey, Chris. I could see how that can happen, for sure. I have the headers installed correctly. The encoders are working, so I'm taking that to indicate the control board header is installed correctly, anyway.
Wayne
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Re: Pushbuttons are not responding
Check the values of R301 and R302 to ensure they match the schematic. Do this with the control board disconnected. Pin 6 of the connector through the resistor and switch to ground.
-mike/w1mt
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Re: Pushbuttons are not responding
Wayne, are the encoder buttons working? If they are also not working you should check for continuity from the ground side of any of the buttons?back to a main board ground point. It's probably a good idea to check continuity to the main board ground from each of the 4 buttons anyway. If it's just the two little push buttons, then you might also check to see if resistors R301 and R302 are present and undamaged. Good luck ... Ron
Hey, Chris. I could see how that can happen, for sure. I have the headers installed correctly. The encoders are working, so I'm taking that to indicate the control board header is installed correctly, anyway.
Wayne
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Re: Pushbuttons are not responding
Hey, Chris. I could see how that can happen, for sure. I have the headers installed correctly. The encoders are working, so I'm taking that to indicate the control board header is installed correctly, anyway.
Wayne
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Bruce Akhurst
Ronald Taylor