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GIUSEPPE
Good evening everyone, today the SMPS cards arrived after almost a month of waiting, the post offices here in Italy work badly, well, this evening I replaced them, no shorts on them, I carefully checked all the soldering and I have no found no problem, I connected the QMX to the PC and it is not detected by win 10 whether powered with 7V or with 8, 9 and 12 V at 500 mA. Would anyone have any suggestions for me to do further tests.? Thank you very much 73 IU8EUN Giuseppe iu8eun |
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GIUSEPPE
By increasing the current to 1 A the Qmx turned on for about 10 seconds, it was connected to the PC with win 8 and it was detected, then I smelled a burning smell and I immediately disconnected the voltage, I noticed that the card underneath the SMPTs was a little hot and it didn't turn on anymore.? I hope it can be repaired.? 73 Giuseppe iu8eun Il Mer 20 Set 2023, 21:02 GIUSEPPE via <iw8rsb=[email protected]> ha scritto:
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Old fashioned fault finding. ? Print out board layout Check component placement and polarity? |
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At least yours didn't start on fire. c.f. /g/QRPLabs/topic/101250291#109570
I'm still waiting on my SMPS replacements. Though your experience doesn't give me much hope. I've done a lot of testing on my board. I have used 5v and 3.3v supplies rigged in to power up the QMX and load firmware onto it so I know the cpu works and the usb connector works. Hope my new SMPS boards work. |
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GIUSEPPE
Thanks Bruce and Nic.? Yesterday I tested the QMX and checked millimeter by millimeter with the magnifying glass and I didn't find any shorts, the SMPS boards seem to be ok, the only thing I would like to do is replace Q103 and D101, I found on the connector of the antenna between the two poles which is shorted, I don't know if it's normal or I should worry, however only the fact that a day ago the PC detected the QMX makes me have doubts about the ignition encoder, I wouldn't want it to be faulty.? I have no other means available to research a possible problem elsewhere on the board.? I hope someone can help me fix it, I wanted to go on air in cw too much, otherwise I will continue to work with the QCX MINI for 20 meters as I always have.? thank you and have a good day.73 Giuseppe iu8eun Il Ven 22 Set 2023, 03:23 Nic Heath <nicheath@...> ha scritto: At least yours didn't start on fire. c.f. /g/QRPLabs/topic/101250291#109570 |
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Giuseppe,
Before ordering new SMPS cards, I recommend removing both cards and verifying resistance on the Vdd and Vcc pins of the main board (see attached pdf from Colin K6JTH).? If there is a short on the main board, replacing the cards will not help. A shorted Vdd could be any of several devices.? My first QMX failed, so I removed things until I reached the MCU (IC203).? The short remained, so I believe that the MCU is dead.? The MCU is not replaceable, so it is in the scrap bin for parts. I hope your experience is better. 73 Evan AC9TU |
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Giuseppe, The qmx pin out drawing is very useful to me.? My qmx will only turn on and? get as far as the splash screen and thats it(it wont turn off).? I carefully checked all 10 pins in the diagram? only one has an incorrect voltage. My ADC_5V shows only 2.5v (dc)should this be 5 volts?
i replaced the SMPS boards.? Is my 2.5v to low? I resoldered the pin checked with multimeter and no change. Any advice to get things moveing would be greatly apprecieated. |
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Thank you Gyula, yes but I dont see my problem anywhere.? I power on load the software i see the splash screen clearly but that is all it wont power off so its not able to complete software loading( i assume) Power down and try again 160ma draw but no screen at all. Have to load the software to get back to splash screen. it lets me load the soft ware each time i do this.? My PC Shows two files ver9 529kb and eeprom 137kb.
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GIUSEPPE
good morning everyone and thanks for your help, Micheal the diagram that Evan sent is very useful for troubleshooting, the problem is that I have already replaced the SMPS cards once, the PC detected the QMX for a few seconds and then I didn't have time to load the firmware and it turned off because the underlying board had heated up.? If I can today I will do further troubleshooting and take Eval's schematic into consideration for a more detailed check.? I'll let you know as soon as I have some positive news.? For now, thank you all for your support and help.? 73 Giuseppe iu8eun Il Sab 23 Set 2023, 14:20 HA3HZ <gyula@...> ha scritto:
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Bruce Akhurst
HA3HZ