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QMX won't power off and odd voltages on Q103
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We are in a hurricane watch and tropical storm ?watch and tornado watch, so to take my mind off the weather, I am trying to get my QMX, Rev 1 going.
I have set my power supply at 7volts and limited current to 200ma. The unit powers on and the LCD turns on but is blank.Brightness does not change when variable resistor adjusted. I am unable to turn the unit off with a long press on left encoder. I have to turn off bench supply. I measured voltage on Q103 with encoder off Gate 6.93 Source 6.68? With unit on, the bench power supply drops to 5.2v and 198ma (But I can't turn unit off) Gate 0.00 Source 4.96 Realizing my first problem is not being able to turn the unit off, I checked and touched up connections on encoder (as usual, the tabs broke off during installation and I used component leads to connect broken tab to appropriate hole). ?During assembly I had to remove the 2x4 female header on the main board because it wasn't straight. One pin of the female header remained in the hole. I removed that by hand and slipped it back into the header. I checked for continuity between the top pins on control board and the solder pins of the female header on bottom of main PC board so I assume that the female header is ok. On the 5V power supply board, I touched up the tabs on the 8 pin female header and checked for any possible shorts between those pins and the source and gate of Q103. I had previously clipped these pins slightly shorter. With bench supply at 8volts (used a higher voltage to see if that might wake up the board), I measured voltage of the pins on top of the female header of ?5V board. Unable to access four pins underneath the board. ?Designating the pin closest to the 1/8" jacks as pin 1, here is what I got: Pin 1 encoder off 7.92 ?on 5 Pin 2 encoder off 0 ?on 1 Pin 3 encoder off 8.0 ?on 5 Pin 4 encoder off 0 ?on 2.16 At this point I am stumped. There is a short somewhere and/or open connection.?I have little electronics theory knowledge, does anyone have any ideas what I should do or would you like to take a look at my unit? (This is about my 6th QRP-Labs kit.) Thanks in advance. Phil, K3UT |
开云体育One thing, you can't turn the QMX off
until you have turned it on.
The turning off process is controlled
by the MCU, it sees the long press and does a load of close down
housekeeping, saving parameters, closing down things, putting the
cat out, then finally turns it's own power supply off.? It's not
death, just sleeping.
But from what you are saying the MCU
hasn't fully started.? You mention that the power goes to your
limit and the voltage drops.? It's less than 5V and too low to get
the 5V supply fully active. This means that the MCU may be in the
start up sequence waiting forever for 5V on the 5V rail.? It
hasn't fully started.
Try increasing the current limit a
little, I wouldn't go over 250mA.? See if that helps.? If it
doesn't then there's something taking too much current from the 5V
supply.? That needs to be found and fixed.? If you can try
checking the 5V PSU board separately, maybe something on that has
shorted.
HTH
Chris, G5CTH
On 30/08/2023 19:32, PHILIP GRAITCER
via groups.io wrote:
We are in a hurricane watch and tropical storm ?watch and tornado watch, so to take my mind off the weather, I am trying to get my QMX, Rev 1 going.
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Did you load firmware? --n1bs On Wed, Aug 30, 2023, 2:32 PM PHILIP GRAITCER via <pgraitc=[email protected]> wrote: We are in a hurricane watch and tropical storm ?watch and tornado watch, so to take my mind off the weather, I am trying to get my QMX, Rev 1 going. |
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I put the bench supply up to 9volts and 250ma. Still couldn't shut it down, so the MCU isn't starting.?
I've looked at the board, and it looks fine visually. There wasn't much I could do to hurt it, since the only thing the builder does is solder the pins of the 2X4 female connector to it. I've checked those and freshened them up several times. Also, I've touched up the pins of the male connector 2X4 where they connect with the main PCB. And I checked those pins for shorting to the Source and Gate of Q103.? Can someone point out some specific steps I should take next? Phil K3UT |
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Of all your measured voltages, 2.16V on the rightmost pin of the 5V connector is the most bewildering. ?That should be the PWR_HOLD signal and either 0V or 3.3V as it's driven by the CPU.
Hans has stated that the bootloader does not enable the SMPS and only runs off the linear regulator (/g/QRPLabs/message/106572).??Have you looked over the 3v3 board to make sure the linear regulator is running? ?LIN_REG_EN (the middle pin on the top) should be higher than 0V when switched on and you should have ~3.3V at D103. It certainly seems like there's a short or bad connection somewhere that might be pulling the 3.3V rail down and preventing the processor from booting. Jonathan KN6LFB |
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Phil,
You also mentioned that the tabs on the rotary encoder broke at one time and you installed wires to repair them. Please check that area for shorts to the rotary encoder housing and that the switch works correctly. Check at the 8 pin connector to make sure you are also checking continuity through the solder joints. 73 Kees K5BCQ |
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Thank you so much for your interest in my problem (s). I think I have more than one problem. The unit won't shut down by pressing left encoder. I have checked and rejected the encoder connections to the board and have made sure they are not electrically touching the encoder body. With probes connected to pins 2&4 of the six pin header and pressing the left encoder, I get a buzz on my multimeter (continuity). ?I reflowed the 6 pin header on control board and now they is a mess of burnt roisin. I can measure continuity from the pins on control board to the main PCB connections on the bottom. I most definitely have an issue. I am not sure which pins are which on the female header on the main PCB so I could short them temporarily in hopes of getting the unit to shut down. If I can, then I my shut down problem is on the control board. On to voltages on the PS boards. If I set my bench supply to 8v, 225ma, I get the following. (When on, voltage drops to 5.25 and 223ma) ? ? ? ? ? ? ? ? ? ? ? ? ?ENCODER OFF ? ? ? ? ? ? ?ENCODER ON 5v board Q103 Gate ? ? ? ? ? ? ? ? 7.92 ? ? ? ? ? ? ? ? ? ? ? ? ? ? 0.0? Q103 Source ? ? ? ? ? ? ?7.69 ? ? ? ? ? ? ? ? ? ? ? ? ? ?5.1 Q105 Gate ? ? ? ? ? ? ? ? ?7.92 ? ? ? ? ? ? ? ? ? ? ? ? ? ?0.0 Q105 Source ? ? ? ? ? ? ?7.69 ? ? ? ? ? ? ? ? ? ? ? ? ? ? 5.14 3 v board IC 101 G ? ? ? ? ? ? ? ? ? ? 0.0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 0.0 IC 101 S ? ? ? ? ? ? ? ? ? ? ?4.7 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 3.2 Measuring the headers of the 5v board: OFF 1=7.93 (leftmost) ? ? 2=0.0 ? ?3=8.0 ? ? ?4=0 ON 1=5.25 ? ? ? ? ? ? ? ? ? ?2=1.26 ? ?3=5.28 ? ?4=2.375 3v board: OFF 1=0 ?(leftmost) ? 2=0 ? ? ? 3=0 ON 1=0 ? ? ? ? ? ? ? ? ? ? 2=5.08 ?3=5.1 D103 ? 2.426 when unit on instead of -3.3V ?as you suggested. Grounding the 78M33 (middle pin) turns the unit off I am confused and do not know what should be my next step. I keep doing the same thing over and over and getting the same results which is the definition of insanity. I hate to give up, but I am stumped. Thanks for your thoughts Phil |
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I suspect a partial/resistive short from one of the power rails to ground.
1. Can you provide photos of the bottom of the main board and the bottom of the power supply boards? 2. If you remove power, what resistance to ground do you have in the following locations on the 3v3 board: ? ?a. The rightmost pin of the board connector? ? ?b. The side of D103 closest to IC101 (away from the connector) 3. Do any of these resistances change if you remove the 5V board? 4. Replacing the 5V board, what is the resistance to ground on the?left side of D108 (towards the audio board) Jonathan KN6LFB |
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On Thu, Aug 31, 2023 at 07:53 PM, PHILIP GRAITCER wrote:
D103 ? 2.426 when unit on instead of -3.3V ?as you suggested.Phil, The output of D103 should be "approximately" 3.3V (that's not a minus sign) and 2.426V is way on the low side. Grounding the LIN_REG_EN pin and turning the 78M33 OFF is good. Does it stay OFF when you remove the grounding ? That would indicate control had been handed to the processor and it enabled the 3.3V SMPS. Speaking of firmware and loading new firmware have you reloaded the latest code AND checked the USB-C connector for good solid connections.?Hans recently released video (52 things....) shows relatively good soldering on the 16 USB-C connector pins but there are apparently a number of boards out there which are not nearly as well soldered and have "iffy" connections. I have posted details in other threads. The reason I call it an "iffy" connection is because the GCT USB4085 connector has 62mil length pins and the board is about 62mils thick. The pins also measure 0.15mm x 0.22mm and the plated via hole is 0.40mm+/-. That's not like "a BB in a rain barrel" but it does indicate good solder wicking between the pin and the via barrel is required. Since soldering those 16 pins is very difficult for the manufacturing facility it generally picks up a little solder from the via barrel plating ......but many times there is too much space between the via barrel and the pin. The result is poor or no electrical contact. Fortunately the 16pin USB-C connector is "reversible" and there are 2 pins for each signal which Hans wired together on the artwork ....so the chances of making a "good connection" are better but not 100%. Sure hope I didn't confuse anyone more.... just trying to help. 73 Kees K5BCQ |
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Hi Kees Remember also that we do test the USB connection of all boards here before shipping. The recommendation to add a bit more solder is more about long life. Since it doesn't intuitively look that secure even if there definitely is an electrical connection.? 73 Hans G0UPL On Fri, Sep 1, 2023, 6:49 PM Kees T <windy10605@...> wrote: On Thu, Aug 31, 2023 at 07:53 PM, PHILIP GRAITCER wrote: |
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