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New Build, No Flash Drive found
#build
#building
#qmx
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On Wed, Apr 2, 2025 at 02:09 PM, VA2OJD wrote:
Would that be indicative of anything underlying problems or is that simply the screen's nature??I think it indicates something very wrong.? Has it always been this bright?? The screen backlight, properly working, is brighter than some prefer, but it is far from being bright enough to wash out the LCD.? I have 4 QMX/QMX+ devices of different hardware versions, and the display works similarly on all of them, with a full range of contrast adjustment. ?
It would be helpful to measure the voltage on pins 15 and 16 of the display connector (the backlight pins) or the resistor.? Is it 5v?? Or do you somehow have a higher voltage there?? If it is 5V, perhaps the particular display you have was intended for 3V operation, and I would put an even larger value resistor in to reduce the current.? |
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Thought i would update - indeed it was some short on the power board.? Got the new boards, slapped it in praying i would get back to at least seeing the USB drive but in fact the QMX booted up and was working just fine.
...until it wasn't.?
Made CW and FT8 QSOs and was hitting across north america and into europe on RBN then suddenly nothing.? I am assuming i somehow popped my BS170s??? no power showing as output on teh diagnostic screens, otherwise everything seems to be within optimums as shown in the operating manual.
Any thoughts?
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Also, my screen is retina-seering bright.? No contact between screen pin3 and power board as suggested elsewhere.? i have removed the r306 and put in a 110ohm resistor.? Brightness has come down, but i am still at the very counter-clockwise end of the contrast control to see anything.? Any movement of the pot counterclockwise and the screen washes out.? Would that be indicative of anything underlying problems or is that simply the screen's nature?? I have much better contrast control on my old QCX mini
JD |
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Hi Russ and Stan.? thanks for the support.? I do seem to have proper resistance between VCC adn VDD and ground.? I have ordered new boards (and in fact a whole new QMX kit just in case).
I also detected a poorly connected leg of the binocular T507 transformer.
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Hoping I didn't cook the entire radio, but will have to wait for the new boards.? I have successfully built the QCX mini and the (tr)uSDX, so crossing my fingers that I didn't fall apart on the QMX
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Thanks again for your answers.
JD |
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Yes, the same SMPS boards work on all revs of QMX and rev 1 of QMX+. On Fri, Mar 21, 2025 at 10:37?AM va3rr via <va3rr=[email protected]> wrote: jd |
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You can test the power supply boards independently, using a procedure which you can find in the wiki for this group, and then potentially repair one by replacing parts.
You can also order a new set of power supply boards from qrp-labs for $10 plus shipping.
Make sure it is really the SMPS boards that are the problem, by removing them, and measuring the resistance between Vcc and Gnd, and Vdd and Gnd on the main board.? These should both be a few k-ohms.? If they are much less, you may have an issue on your main board.
Stan |
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I had a similar problem - after my build i got the USB drive, loaded the firmware, which seemed to load, but then absolutely nothing.? Forced back into USB drive and the firmware was there.? Reloaded it.? Nothing.
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then I smelled the warm, sick smell of cooking electronics.? the left power board (smps board?) was *very* hot and it looks just like the problematic smps board in the troubleshooting pages where there is a short between the Q103/Q104.
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Is there a fix for that?? Can I buy a new board??
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My QMX is (was??) Rev 4.? Ordered a couple weeks ago. When I look at the photo of the board on the front page of teh Rev 4 assembly manual, it is clear that there is space between Q103-Q104. On my mine the Q104 drain looks like it is underneath the larger unit.
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Thanks for any advice
JD |
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On Wed, Jun 19, 2024 at 03:31 AM, Bill - AA4NO wrote:
showing 2 Ohms so the STM32 seems to be dead again.Hello Bill, I don't belive in a dead STM32 recover to live die again and recover again. Imho it looks more like a bypass related to the inner voltage supply system. It affects VDD and maybe something more. Sorry, but I have no idea how to search for this failure from remote. I'm sure Jeff Moore, W1NC would give you the right help. 73, Ludwig |
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First off Ludwig a big THANKS for all your help.??
I had some limited success today.? I remembered that when It did show up as as USB drive I started the firmware load but the USB Drive went away as? soon as the copy started.? So I thought maybe it had a partial load of the firmware.? I used the jumper to force the firmware update and it WORKED.? I was able to see the QMX USB drive and it did not fail.? I copied the firmware and the QMX rebooted.? But the display never showed any activity and the back light did not come on.? But the QMX seemed to be booted.? It was drawing only about .25 amps and was not getting hot.? I checked the voltage at PCB#1 and PCB#2 and I had voltage at +12V which is only available after power on,? Vcc had about 3V and Vdd was about 2v which is low but seems to indicate it was partially working. PWR_HLD had about 2v, again low but it showing that something was working.? I shut it down and re-flowed the solder at the PINS for the Display.? Booted it back up but still no display.? I tried the Jumper to force a boot and it came up as a USB Drive again.? I then shut it down and took a break.? When I tried to power it back on pressing the Left Encoder did not power it back up.? I had no current draw at all.? This is what I was seeing when I first tried to power it on at first build.? I checked the Vdd with all the cards removed and it is now only showing 2 Ohms so the STM32 seems to be dead again.? ?This was back to where I started this debug process.?? Also, a few days ago it was doing the same thing, when the Left Encoder was pressed the voltage would show a slight drop but the QMX had no current draw at all.? Then without doing anything after sitting a few hours I tried it again and it would start to draw a current and get a little warm. It seems I either received a defective STM32 or I damaged something during my build process.? ? I have ordered another kit and will give it another go hopefully with better results.?? Again thanks for all the help and support.?? Bill |
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On Mon, Jun 17, 2024 at 02:54 AM, Bill - AA4NO wrote:
Step 4: measure the real internal voltage at "VDD" using your DMM when left encoder pressed.Hello Bill, 0.6 V to low. With 6.62 V at "+12V" you should see 3.3 V at VDD. Maybe overload at VDD? Step 5: Check temperature of IC101 after pressing left encoder for 20 seconds or so. Hot like decriped before?To much current for VDD. Maybe overload at VDD. Step 6: Without supply check resistance from "+12V" to GND with all the sub PCB connected to the mainboard.More than 10 k ohm would be ok. Something connected to "+12V" is wrong. I also noticed that the STM 32 processor is a slightly warm to the touch.Checking my running QMX I don't feel this. I think there is a high probability for a broken STM32. To be proof you may remove elements from VDD one after an other (I know, not so easy). 73, Ludwig |
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>>>> Bill, I guess this is the resistace 23.5 ohm?
YES 23.5 ohm,? what should it be?? >>> In this situation the controller could be faulty, no repair (until now.) But you found some short USB connections. So the controller maybe not broken, good mesage. To get a consistent picture please collect a consistent set of data. Use 7 V supply limited to 0.35 A for Step 1 to 5. Step 1: measure the real supply voltage using your DMM when left encoder pressed. ? ?Voltage in was 7V,? when the left Encoder pressed it dropped to 6.8V? Step 2: measure the real supply current using your DMM when left encoder pressed. ? ?Current was Zero, when left Encoder pressed it was .35 which was the limit.? I increased the limit slightly and it stabilized at .365 amps Step 3: measure the real internal voltage at "+12V" using your DMM when left encoder pressed. ? ? 6.62 volts measured Step 4: measure the real internal voltage at "VDD" using your DMM when left encoder pressed. ? ? 2.72 volts Step 5: Check temperature of IC101 after pressing left encoder for 20 seconds or so. Hot like decriped before? ? ?It is still warm, You can touch it but if you hold your finger on top it gets very warm.? Step 6: Without supply check resistance from "+12V" to GND with all the sub PCB connected to the mainboard. ? ?22 oms was measured? I also noticed that the STM 32 processor is a slightly warm to the touch.? No USB Drive shows up so that only worked for a few minutes a few times.? ? Thanks very much for all your help,? Bill ? ?? |
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On Wed, Jun 12, 2024 at 02:00 AM, Bill - AA4NO wrote:
The VDD is up to 23.5?Bill, I guess this is the resistace 23.5 ohm? In this situation the controller could be faulty, no repair (until now.) But you found some short USB connections. So the controller maybe not broken, good mesage. To get a consistent picture please collect a consistent set of data. Use 7 V supply limited to 0.35 A for Step 1 to 5. Step 1: measure the real supply voltage using your DMM when left encoder pressed. Step 2: measure the real supply current using your DMM when left encoder pressed. Step 3: measure the real internal voltage at "+12V" using your DMM when left encoder pressed. Step 4: measure the real internal voltage at "VDD" using your DMM when left encoder pressed. Step 5: Check temperature of IC101 after pressing left encoder for 20 seconds or so. Hot like decriped before? Step 6: Without supply check resistance from "+12V" to GND with all the sub PCB connected to the mainboard. 73, Ludwig |
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Thanks for all your help,?
The VDD is up to 23.5? I don't see any shorts,? I am not sure how to follow the rails.? I am looking at the schematic but don't really understand it that well.? I have the voltage limited to 7 volts and current to .350 amps.? I connected a USB cable but I no longer see a USB drive.? ? |
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On Tue, Jun 11, 2024 at 11:39 PM, @Ludwig_DH8WN wrote:
Check visual around the VDD rail. Check the resistance from VDD to GND (see here Debugging - No 1)Please check it again to see is there a difference to 16.1 Ohm before. |
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On Tue, Jun 11, 2024 at 10:27 PM, Bill - AA4NO wrote:
it is a fabric, not specifically anti-static.Bill, maybe it could collect electric static charges. This would be dangerous for the QMX and other modern electronic parts. and I could see a current draw of about .3 amps.0.2 A would be fine. But lets go forward. The whole time before the firmware is working IC101 regulates the 3.3 V (see here). When using 12 V you have a voltage drop of around 8 V. This makes around 2.4 W loss by IC101 and will heat the circuit more than for 0.2 A. ?IC101 on the power supply was HOT to the touch. but a after about 30 seconds the drive disconnected.Inside IC101 is a thermal overload protection. I guess this kicks in and switch IC101 off. So you have to search for the to high load at VDD rail. Check visual around the VDD rail. Check the resistance from VDD to GND (see here Debugging - No 1) Later for tests you may use only 7 ... 9 V input to lower the thermal power at IC101. But don't load the firmware. First search the cause for the 0.1 A additional current. Check the relevant elements for higher temperatures. It's only 0.33 W, not so much heat and maybe not enough to find it. Check the exact voltage at VDD (see here). 73 Ludwig |
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it is a fabric, not specifically anti-static.??
So new symptoms.? I tried to power it up again and this time I noticed that after the left encoder was pressed the voltage did not drop and I could see a current draw of about .3 amps.? I connected the USB cable and a QMX drive showed up.? Happy Days..... but a after about 30 seconds the drive disconnected.? Powered the qmx off and then tried again.? Same results, Drive shows up but only for 30 seconds,? Then I noticed some heat from the QMX and found IC101 on the power supply was HOT to the touch.? Close inspection and no solder bridges.? Also no more USB drive showing up even briefly.? ? Looking at the group messages but don't see anything similar yet.....? Bill |
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On Tue, Jun 11, 2024 at 07:35 PM, Bill - AA4NO wrote:
With all boards removed I get 16.1 Ohm at VDD if I am reading the meter with the correct scale.Bill, sorry, it's bad. This means you have a broken element connected to the VDD rail. With all the boards reinstalled and with power applied.... ...VDD shows still reads 16 Ohm with the board power supplied.???, did you measure resistance with power connected and left encoder pressed? This brings wrong results and your DMM is endangered. You should measure voltage at Vdd with power supplied and left encoder pressed. 73, Ludwig |
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Ludwig
With all boards removed I get 16.1 Ohm at VDD if I am reading the meter with the correct scale.? See Picture,?? I checked the power board, I have a version 3 board and I do not have a short.? I checked the resister and diode and they both check good.?? With all the boards reinstalled and with power applied.... At PCB#1 I show Vin (batt level) as 7 or 12 volts depending on what I am limiting the supply to.? Power_on shows the battery voltage that is supplied.? When the left encoder is pressed it does short to ground as expected.? VDD shows still reads 16 Ohm with the board power supplied.? ?It also shows a connection to ground which I think is correct??? everything else at PCB#1 and PCB#2 shows as 0 volts which I would expect since the firmware has never been loaded so it has not yet booted.?? What else should I be looking for??? Thanks very much for your help? 73 AA4NO Bill |
va3rr
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