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QMX+ Startup Issues

Ray D Congdon All Messages By This Member #125008 First, not a newbe here.? But I don't know everything!? I have built a lot Electronics kits going back to Heathkits, Knightkits, etc. and have recently successfully? constructed 4 QDX's, a 40M QCX and a regular QMX, so have some experience with the Product. That out of the way... Upon power up with a current limited PS @ 8V and 250ma limit, I got 11ma current drain upon power button press.? In troubleshooting I discovered that the D103 on the obverse side of the small SMPS board had been knocked off in shipment (and the inductors were also chipped) and was floating around in the shipping bag... Unfortunately the damage had removed a pad and I could not repair the board but, having a new un-built QMX for a friend available, I installed a new SMPS. I then got? a current limited (250ma) drain and heating on the 7833 Lin reg while the button was pressed (0ma when not).? Using an IR camera I found that the only other hot spot was the MPU...? Not particularly good news.? I have gone over the washed board with a microscope and have not found any visible errors or bridges. Any thoughts?? I have ordered a couple of replacement SMPS boards and a new QCX+ basic kit just in case. Ray - KL7UT?
[email protected] All Messages By This Member #125016 Just to be clear, the "new" SMPS is out of a known-working QMX, right? Check the voltages.? There is an unpopoulated 2x3 header with Vin, Gnd, Vcc and Vdd labeled on the main board right by the SMPS boards.
@Ludwig_DH8WN All Messages By This Member #125037 Ray, please read two documents from the QRP Labs Wiki about QMX start up ?? and QMX internal power supply. You will find some information to check your QMX how far this process is going and to find the place of the failure. 73, Ludwig
Ray D Congdon All Messages By This Member #125063 I did read the referenced doc, Thanks!? For reference, I found the following voltages: 9 volt supply, Current Limited (to 250ma)? Idle (Power button not pressed)? Vin -? 9.00V V+ - 0.00 Vcc - 0.00 Vdd - 0.00 Button depressed (Over Current Maxed @ 250ma) Vin - 5.55V V+? - .55V Vcc - .001V? Vdd? - .67 Power disconnected Ohm meter readings on Vdd to Gnd - 1.67? Ohms either polarity After diligent ohm meter work determined that the lowest (1.5 Ohms) is at the Vdd inputs to the MPU. I decided to risk it and hot-aired the MPU off of the board...? Sure enough Vdd to Gnd is now 6K / 3.5K Ohms.? No sign of any solder bridges or such on the MPU Pins.? So, it looks like a damaged IC-203 MPU? If you read this Hans, Can I get a spare MPU in My recent order?? I'm quite willing to pay for it.?? ?
Greg McCain All Messages By This Member #125077 I apologize for not having the exact place to look in the docs or group messages BUT ... I believe I saw instructions and personally tested Vdd and Vcc to ground with no PSU boards and of course with no power applied to verify that the expected value was in Mega Ohms. Anything less meant, I thought, that one or more components were damaged internally.? Perhaps others in the group could verify that condition and find the written reference? 73 GREG KI4NVX? toggle quoted message Show quoted text On Sat, Jun 29, 2024 at 6:28 PM, Ray D Congdon via groups.io <kl7ut@...> wrote: I did read the referenced doc, Thanks!? For reference, I found the following voltages: 9 volt supply, Current Limited (to 250ma)? Idle (Power button not pressed)? Vin -? 9.00V V+ - 0.00 Vcc - 0.00 Vdd - 0.00 Button depressed (Over Current Maxed @ 250ma) Vin - 5.55V V+? - .55V Vcc - .001V? Vdd? - .67 Power disconnected Ohm meter readings on Vdd to Gnd - 1.67? Ohms either polarity After diligent ohm meter work determined that the lowest (1.5 Ohms) is at the Vdd inputs to the MPU. I decided to risk it and hot-aired the MPU off of the board...? Sure enough Vdd to Gnd is now 6K / 3.5K Ohms.? No sign of any solder bridges or such on the MPU Pins.? So, it looks like a damaged IC-203 MPU? If you read this Hans, Can I get a spare MPU in My recent order?? I'm quite willing to pay for it.?? ?
@Ludwig_DH8WN All Messages By This Member #125098 On Sun, Jun 30, 2024 at 12:57 PM, Greg McCain wrote: I believe I saw instructions and personally tested Vdd and Vcc to ground with no PSU boards and of course with no power applied to verify that the expected value was in Mega Ohms. Anything less meant, I thought, that one or more components were damaged internally.? Afaik a value around 10 kiloohm would be also ok. Something around a few ohms is bad. Maybe this document from the QRP Labs Wiki could be helpful.
Greg McCain All Messages By This Member #125101 My bad remembering. :)? Thanks Ludwig. Greg toggle quoted message Show quoted text On Sun, Jun 30, 2024 at 7:04 PM, DH8WN@... <DH8WN@...> wrote: On Sun, Jun 30, 2024 at 12:57 PM, Greg McCain wrote: I believe I saw instructions and personally tested Vdd and Vcc to ground with no PSU boards and of course with no power applied to verify that the expected value was in Mega Ohms. Anything less meant, I thought, that one or more components were damaged internally.? Afaik a value around 10 kiloohm would be also ok. Something around a few ohms is bad. Maybe this document from the QRP Labs Wiki could be helpful.
@Ludwig_DH8WN All Messages By This Member #125123 On Sun, Jun 30, 2024 at 12:28 AM, Ray D Congdon wrote: Button depressed (Over Current Maxed @ 250ma) Vin - 5.55V V+? - .55V Ray, a voltage drop of 5V across Q103 and Q105 is strange. Power disconnected Ohm meter readings on Vdd to Gnd - 1.67 ?Ohms either polarity With all subboards removed? I decided to risk it and hot-aired the MPU off of the board... ?Sure enough Vdd to Gnd is now 6K / 3.5K Ohms.? Imho it's a bit to low. Could there be a different problem, maybe affected by the hot air? 73 Ludwig
Ray D Congdon All Messages By This Member #126492 Update: 7/22/2024 ? Hans provided a new MPU at very reasonable cost.? ? While doing a through clean-up of the board in preparation to install it, I found a whisker of solder between two pads on the MPU pattern... Probably created during the Hot-air removal of the MPU as noted by Ludwig (Thanks!).? Cleared that and the PS rails went to just seeing a bit of capacitor charging leakage (>10k).? ? Installed the new MPU.? (I'm getting too old for this I thought many a time during this process!!! I use and old-school binocular microscope...) ? Repaired the 3.3V Reg board by installing a leaded 1N4198 diode between the output of the 3.3 lin reg and the 3.3V pin 4? to replace the damaged (missing) D104 SMT diode. ? Built a jig to test the Power supply boards and tested them per the instructions in the Wiki here.? PSU's all Ok now. ? Did power-up checks and flashed the system...? Viola! It lives!?? ? All happy! ? Many thanks to all for the trouble-shooting advice and to Hans & Crew for a great kit! ? Ray, KL7UT ? ?
Gordon Young All Messages By This Member #126504 This is encouraging! I have a similar issue. My MPU was dead before I could ever get my QMX flashed. How do I request to purchase a new micro-controller with the QMX bootloader installed? Thanks! ~Gordon Gordon Young gordon.j.young@... WA8Q
Ray D Congdon All Messages By This Member #126550 Actually, Hans replied to me from my post with instructions as to how to order it.? I'd direct a query to him and see if he has more available.??

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