|
Hello,
I have build a QMX rev2 but when I connect 12 volt nothing happens no current also not when I press the left rotory
It is completly dead also no usb device is detected at the computer, I see also no voltage at l202 to the micro contraller.
This my ever first kit wiich did not work i have build several such as QDC XCQ en WSPR tx GPs etc
I am a bit lost how to go forward where should I start? At the buck converter i see only 12 volt
Who can help me to get it working, or some testplan to proceed
73 Frans PE0F
|
Frans,? I would begin by looking carefully around IC101, the 78M33 3.3V linear regulator. What voltage do you see at each of its three terminals?
JZ KJ4A?
Hello,
I have build a QMX rev2 but when I connect 12 volt nothing happens no current also not when I press the left rotory
It is completly dead also no usb device is detected at the computer, I see also no voltage at l202 to the micro contraller.
This my ever first kit wiich did not work i have build several such as QDC XCQ en WSPR tx GPs etc
I am a bit lost how to go forward where should I start? At the buck converter i see only 12 volt
Who can help me to get it working, or some testplan to proceed
73 Frans PE0F
|
Also, first check to see if the 12V input to the 3.3V regulator board comes up when QMX is told to turn on.
JZ
Frans,? I would begin by looking carefully around IC101, the 78M33 3.3V linear regulator. What voltage do you see at each of its three terminals?
JZ KJ4A?
Hello,
I have build a QMX rev2 but when I connect 12 volt nothing happens no current also not when I press the left rotory
It is completly dead also no usb device is detected at the computer, I see also no voltage at l202 to the micro contraller.
This my ever first kit wiich did not work i have build several such as QDC XCQ en WSPR tx GPs etc
I am a bit lost how to go forward where should I start? At the buck converter i see only 12 volt
Who can help me to get it working, or some testplan to proceed
73 Frans PE0F
|
Chris, G5CTH,?documented a process to check out each of the buck converter boards in this post: It requires a controllable voltage, current limiting, ?power supply.? You could do some of the tests with just a voltage-controllable supply.
Hans has posted a description of the startup process that the QMX goes through.?? /g/QRPLabs/message/103064Use this with the schematic and board layout to work through where the voltage is getting lost.? Be very careful when probing.? When the board is removed from the case, it is easy to push things in the wrong direction and wipe out the main board (don't ask). 73 Evan AC9TU
|
Thanks, Evan. I had completely forgotten about that resource...JZ
On Sat, Dec 30, 2023, 2:12?PM Evan Hand < elhandjr@...> wrote: Chris, G5CTH,?documented a process to check out each of the buck converter boards in this post:
It requires a controllable voltage, current limiting,?power supply.? You could do some of the tests with just a voltage-controllable supply.
Hans has posted a description of the startup process that the QMX goes through.??
/g/QRPLabs/message/103064
Use this with the schematic and board layout to work through where the voltage is getting lost.? Be very careful when probing.? When the board is removed from the case, it is easy to push things in the wrong direction and wipe out the main board (don't ask).
73
Evan
AC9TU
|
I’d check the connections on your left rotary encoder first.
|
Evan, your link to Chris’s troubleshooting isn’t working for me. I will do a search but if you have another way to link it I would appreciate it!
73,
David Hoskins
WB5GNR
Sent remote...
|
David, Sorry, I copied the save link from my Gmail account.? It is good that it did not work ;-) Here is the 开云体育 link: /g/QRPLabs/message/10678773 Evan AC9TU
|
Hi JZ
good tip indeed no 3.3 volt! all 2(3) 0 Volt
on Q103 Ans Q105 12.6 and 12.2 on pin 1 and 3
PE0F Frans
|
Frans, forgive me. I am having? some difficulty understanding what you have seen.
You said that the 3.3V supply is not up. OK! Nothing will actually run until it is up.
The rest of your message needs clarification.
Can you see voltage on the line labelled +12V when you activate QMX via the left encoder switch? If not, check the connections at the encoder.
If so, does that voltage make its way to the input if the 3.3V regulator board?
JZ
Hi JZ
good tip indeed no 3.3 volt! all 2(3) 0 Volt
on Q103 Ans Q105 12.6 and 12.2 on pin 1 and 3
PE0F Frans
|
JZ
good tip indeed no 3.3 volt! all 2(3) 0 Volt means, all the pins of the 78m33 are 0 Volt
103 Ans Q105 12.6 and 12.2 on pin 1?means Q103 en Q105 pin 1 and 3 I measure 12 volt
on the switch I measure 12 volt on 1 side an 0 on the otherside of the switch
If I press the switch both pins become 0 volt and i see a small cuurent is drown form the PSU
but no voltage on the 78m33 stil all pins stay 0
where does the supply voltage? come from to feed the 78m33 ? and how much should this be ?
I can understand I it needs 3.3V to run
73 Frans
|
Hello Frans,
The 12 volts feeding the 78M33 comes from the Plug-in PCB #1 (5 volt SMPS board).? Pressing the left encoder grounds the "PWR_ON" flag, which turns on Q103 and Q105 while holding the button.? "PWR_HOLD" comes from the MPU to turn the two transistors on through Q104.? What is not happening is the MPU is not turning on that signal.
I had your symptoms with my first QMX build.? This was after I found a problem with the control board and tried to diagnose it while exposed on the bench.? I somehow damaged the MPU during testing, and that kit is now spare parts.?
Try removing both SMPS boards, the display, and the control board.? Verify the resistance of Vdd to ground on the main board.? For my failed unit, it was 0 Ohms.? I had fried the MPU.
I hope you do not have the same problem; replacing the MPU or scrapping the kit are the only choices.? Hans may make the MPU with his proprietary bootloader available for those capable of replacing the MPU.? I have not yet seen that offer on the web.
73
Evan
AC9TU
|
Evan, Frans,
Frans, first my thanks for a clear and concise response. It is very helpful.
Evan, take a look at Frans' description again , and the schematic, too.
....
Q103 en Q105 pin 1 and 3 I measure 12 volt
on the switch I measure 12 volt on 1 side an 0 on the otherside of the switch
If I press the switch both pins become 0 volt and i see a small cuurent is drown form the PSU
but no voltage on the 78m33 stil all pins stay 0
...
Could a failed D101 diode or a bad solder?joint there be responsible?for what Frans is seeing??
JZ ?
On Sun, Dec 31, 2023, 7:52?AM Evan Hand < elhandjr@...> wrote: Hello Frans,
The 12 volts feeding the 78M33 comes from the Plug-in PCB #1 (5 volt SMPS board).? Pressing the left encoder grounds the "PWR_ON" flag, which turns on Q103 and Q105 while holding the button.? "PWR_HOLD" comes from the MPU to turn the two transistors on through Q104.? What is not happening is the MPU is not turning on that signal.
I had your symptoms with my first QMX build.? This was after I found a problem with the control board and tried to diagnose it while exposed on the bench.? I somehow damaged the MPU during testing, and that kit is now spare parts.?
Try removing both SMPS boards, the display, and the control board.? Verify the resistance of Vdd to ground on the main board.? For my failed unit, it was 0 Ohms.? I had fried the MPU.
I hope you do not have the same problem; replacing the MPU or scrapping the kit are the only choices.? Hans may make the MPU with his proprietary bootloader available for those capable of replacing the MPU.? I have not yet seen that offer on the web.
73
Evan
AC9TU
|
What is puzzling me is that Frans reports seeing 12V at Q103 and Q105 but not at the input of the 78m33 regulator.
It is as if there is a fault of some kind at Q101/R101 that is preventing Q102 from turning on.
Frans, with power turned off, can you measure the resistances at Q101: gate to source, gate to drain, drain to source ? ? JZ
JZ
Evan, Frans,
Frans, first my thanks for a clear and concise response. It is very helpful.
Evan, take a look at Frans' description again , and the schematic, too.
....
Q103 en Q105 pin 1 and 3 I measure 12 volt
on the switch I measure 12 volt on 1 side an 0 on the otherside of the switch
If I press the switch both pins become 0 volt and i see a small cuurent is drown form the PSU
but no voltage on the 78m33 stil all pins stay 0
...
Could a failed D101 diode or a bad solder?joint there be responsible?for what Frans is seeing??
JZ ? On Sun, Dec 31, 2023, 7:52?AM Evan Hand < elhandjr@...> wrote: Hello Frans,
The 12 volts feeding the 78M33 comes from the Plug-in PCB #1 (5 volt SMPS board).? Pressing the left encoder grounds the "PWR_ON" flag, which turns on Q103 and Q105 while holding the button.? "PWR_HOLD" comes from the MPU to turn the two transistors on through Q104.? What is not happening is the MPU is not turning on that signal.
I had your symptoms with my first QMX build.? This was after I found a problem with the control board and tried to diagnose it while exposed on the bench.? I somehow damaged the MPU during testing, and that kit is now spare parts.?
Try removing both SMPS boards, the display, and the control board.? Verify the resistance of Vdd to ground on the main board.? For my failed unit, it was 0 Ohms.? I had fried the MPU.
I hope you do not have the same problem; replacing the MPU or scrapping the kit are the only choices.? Hans may make the MPU with his proprietary bootloader available for those capable of replacing the MPU.? I have not yet seen that offer on the web.
73
Evan
AC9TU
|
Also, check the solder joints at the connector pin that brings +12V to the 3.3V regulator board.
JZ
What is puzzling me is that Frans reports seeing 12V at Q103 and Q105 but not at the input of the 78m33 regulator.
It is as if there is a fault of some kind at Q101/R101 that is preventing Q102 from turning on.
Frans, with power turned off, can you measure the resistances at Q101: gate to source, gate to drain, drain to source ? ? JZ
JZ
Evan, Frans,
Frans, first my thanks for a clear and concise response. It is very helpful.
Evan, take a look at Frans' description again , and the schematic, too.
....
Q103 en Q105 pin 1 and 3 I measure 12 volt
on the switch I measure 12 volt on 1 side an 0 on the otherside of the switch
If I press the switch both pins become 0 volt and i see a small cuurent is drown form the PSU
but no voltage on the 78m33 stil all pins stay 0
...
Could a failed D101 diode or a bad solder?joint there be responsible?for what Frans is seeing??
JZ ? On Sun, Dec 31, 2023, 7:52?AM Evan Hand < elhandjr@...> wrote: Hello Frans,
The 12 volts feeding the 78M33 comes from the Plug-in PCB #1 (5 volt SMPS board).? Pressing the left encoder grounds the "PWR_ON" flag, which turns on Q103 and Q105 while holding the button.? "PWR_HOLD" comes from the MPU to turn the two transistors on through Q104.? What is not happening is the MPU is not turning on that signal.
I had your symptoms with my first QMX build.? This was after I found a problem with the control board and tried to diagnose it while exposed on the bench.? I somehow damaged the MPU during testing, and that kit is now spare parts.?
Try removing both SMPS boards, the display, and the control board.? Verify the resistance of Vdd to ground on the main board.? For my failed unit, it was 0 Ohms.? I had fried the MPU.
I hope you do not have the same problem; replacing the MPU or scrapping the kit are the only choices.? Hans may make the MPU with his proprietary bootloader available for those capable of replacing the MPU.? I have not yet seen that offer on the web.
73
Evan
AC9TU
|
John,
I interpret that pins 1 and 3 of the MOSFETs are source and gate.? That would indicate that Q103 and Q105 turn on when holding down the left encoder.?
You are correct in that Q102 is not turning on.? That is likely because the "LIN_REG_EN" is low from the MPU.? That should start High, and then when ready, the MPU will set it low.? That could be measured as well.
This is the third or fourth post with this type of issue.? In those cases, it came down to a blown MPU.
Franz,
I would still suggest that you measure the resistance on the Vdd line, as your symptoms are identical to mine.??
You could also confirm the voltage on the input to the 3.3-volt regulator while the encoder is pressed and the gate voltage on Q102.
73
Evan
AC9TU
|
Ouch, Evan. Yes that could do it.
JZ
On Sun, Dec 31, 2023, 9:07?AM Evan Hand < elhandjr@...> wrote: John,
I interpret that pins 1 and 3 of the MOSFETs are source and gate.? That would indicate that Q103 and Q105 turn on when holding down the left encoder.?
You are correct in that Q102 is not turning on.? That is likely because the "LIN_REG_EN" is low from the MPU.? That should start High, and then when ready, the MPU will set it low.? That could be measured as well.
This is the third or fourth post with this type of issue.? In those cases, it came down to a blown MPU.
Franz,
I would still suggest that you measure the resistance on the Vdd line, as your symptoms are identical to mine.??
You could also confirm the voltage on the input to the 3.3-volt regulator while the encoder is pressed and the gate voltage on Q102.
73
Evan
AC9TU
|
