开云体育

qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING

harleyleenuke All Messages By This Member #130085 Hello All,, ? I am troubleshooting a dead QMX +.It worked for a few hours and then it died and will not turn on.. Pressing the on button , I see about 23 ma/ draw. let it off and 0 ma. I HAVE A NEWER MAIN BOARD WITH THE POWER SUPplies BUILT INTO THE pcb. ? So I found Diode 103. shorted to ground. It was HOT. I then removed it. The short is now gone. ? ?I pressed the ON button and checked the diode pad and see 4 volts, one side.? ? ?Well now my other problem. I ripped the pads off the board, so I need to install a axial D103 1N148. ? On the schematic. for D103,? It shows from IC 101 VO pin? to VDD .? So Where to ,where? do I connect to VDD ? ? The schematic is hard to some of? the traces on the bottom of the boar. ? Thanks for any help. ? Lee AA7HC ? ?
Steve Beckman All Messages By This Member #130086 开云体育 Hi Lee; D103 provides 3.3 Volts from IC101 to the VDD bus. IC101 has been configured to provide about 3.9 Volts (what you measured) so that after the 0.6 Volt drop across D103, 3.3 Volts is available to the VDD bus. If you measured a short from D103 to ground, then your VDD bus is shorted to ground - which would cause D103 to get hot! You need to find what is causing that short from VDD to ground. 73; Steve, N3SB? toggle quoted message Show quoted text -------- Original message -------- From: harleyleenuke <vfrank59@...> Date: 9/19/24 6:51 PM (GMT-05:00) To: [email protected] Subject: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING Hello All,, ? I am troubleshooting a dead QMX +.It worked for a few hours and then it died and will not turn on.. Pressing the on button , I see about 23 ma/ draw. let it off and 0 ma. I HAVE A NEWER MAIN BOARD WITH THE POWER SUPplies BUILT INTO THE pcb. ? So I found Diode 103. shorted to ground. It was HOT. I then removed it. The short is now gone. ? ?I pressed the ON button and checked the diode pad and see 4 volts, one side.? ? ?Well now my other problem. I ripped the pads off the board, so I need to install a axial D103 1N148. ? On the schematic. for D103,? It shows from IC 101 VO pin? to VDD .? So Where to ,where? do I connect to VDD ? ? The schematic is hard to some of? the traces on the bottom of the boar. ? Thanks for any help. ? Lee AA7HC ? ?
harleyleenuke All Messages By This Member #130093 Steve, ?Thanks for the info.? I checked the ground to vcc and showed 330 ohms.? found D109 Zener Diode exploded.on one end. I did get a voltage reading of 2.1 volts. on it though. ?I removed D109? and the ground is gone. ?Mouser Parts on order.? ?I will update this when I get the part. ?Thanks for the help. ?Lee AA7HC
Steve Beckman All Messages By This Member #130100 开云体育 Lee; Wow - that 3.6 Volt Zener should not have seen an overstress condition sitting on the 3.3 Volt VDD bus - unless the switching regulator did something it shouldn't have. Looking forward to hearing about the result you obtain when the D109 is replaced. 73; Steve, N3SB? toggle quoted message Show quoted text -------- Original message -------- From: harleyleenuke <vfrank59@...> Date: 9/19/24 8:54 PM (GMT-05:00) To: [email protected] Subject: Re: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING Steve, ?Thanks for the info.? I checked the ground to vcc and showed 330 ohms.? found D109 Zener Diode exploded.on one end. I did get a voltage reading of 2.1 volts. on it though. ?I removed D109? and the ground is gone. ?Mouser Parts on order.? ?I will update this when I get the part. ?Thanks for the help. ?Lee AA7HC
Stan Dye All Messages By This Member #130102 A momentary short from the 12V bus to VDD could blow up D103.? Is there something mechanically close that could come together and short these two? Maybe pins contacting the chassis? I don't have QMX+, I got QMXmini, so I can't directly check. toggle quoted message Show quoted text On Thu, Sep 19, 2024 at 8:23?PM Steve Beckman via <n3sb=[email protected]> wrote: Lee; Wow - that 3.6 Volt Zener should not have seen an overstress condition sitting on the 3.3 Volt VDD bus - unless the switching regulator did something it shouldn't have. Looking forward to hearing about the result you obtain when the D109 is replaced. 73; Steve, N3SB? -------- Original message -------- From: harleyleenuke <vfrank59@...> Date: 9/19/24 8:54 PM (GMT-05:00) To: [email protected] Subject: Re: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING Steve, ?Thanks for the info.? I checked the ground to vcc and showed 330 ohms.? found D109 Zener Diode exploded.on one end. I did get a voltage reading of 2.1 volts. on it though. ?I removed D109? and the ground is gone. ?Mouser Parts on order.? ?I will update this when I get the part. ?Thanks for the help. ?Lee AA7HC
Daniel Walter All Messages By This Member #130103 Get new p/s boards! I tried repairing them and there ended up being additional issues. I don't think it's worth risking damage to the main boards with repaired p/s boards. ? Check your Vdd and Vcc resistances (with p/s's removed) to make sure you didn't damage the main board.? -- 73, Dan? NM3A
Steve Beckman All Messages By This Member #130104 开云体育 Stan - good point. A physical connection between +12V and VDD could blow up D103. A couple components that are just a bit too close is all it would take to set up a failure mode when the main board is flexed a bit. My QMX+ is still waiting to be built. I did fix a QMX+ for my good friend Rich N3III a week ago. The problem with his radio was traced to a missing D103. Looked like it was ripped from the board, along with its pads. Fortunately that was easy to fix, and his QMX+ is working super-well now. 73, Steve, N3SB? toggle quoted message Show quoted text -------- Original message -------- From: Stan Dye <standye@...> Date: 9/19/24 10:44 PM (GMT-05:00) To: [email protected] Subject: Re: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING A momentary short from the 12V bus to VDD could blow up D103.? Is there something mechanically close that could come together and short these two? Maybe pins contacting the chassis? I don't have QMX+, I got QMXmini, so I can't directly check. On Thu, Sep 19, 2024 at 8:23?PM Steve Beckman via <n3sb=[email protected]> wrote: Lee; Wow - that 3.6 Volt Zener should not have seen an overstress condition sitting on the 3.3 Volt VDD bus - unless the switching regulator did something it shouldn't have. Looking forward to hearing about the result you obtain when the D109 is replaced. 73; Steve, N3SB? -------- Original message -------- From: harleyleenuke <vfrank59@...> Date: 9/19/24 8:54 PM (GMT-05:00) To: [email protected] Subject: Re: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING Steve, ?Thanks for the info.? I checked the ground to vcc and showed 330 ohms.? found D109 Zener Diode exploded.on one end. I did get a voltage reading of 2.1 volts. on it though. ?I removed D109? and the ground is gone. ?Mouser Parts on order.? ?I will update this when I get the part. ?Thanks for the help. ?Lee AA7HC
harleyleenuke All Messages By This Member #130107 I have the New PCB with the power supplies on the main board. I will inspect everything again. ?Steve where didyou make connection for the D103 ?? ?I am thinking , mine on top of the PCB? IC101 output to a nearby VDD JP106 hole. ? I am unclear if that is correct,? ain't done it yet. Lee, ?AA7HC ? ?
Steve Beckman All Messages By This Member #130118 开云体育 Lee - yes, that's exactly what I did. Anode to U101 on the top of the daughterboard, and Cathode to the 3.3 Volt VDD pin on the bottom side with a short wire.? 73; Steve, N3SB? toggle quoted message Show quoted text -------- Original message -------- From: harleyleenuke <vfrank59@...> Date: 9/20/24 3:31 AM (GMT-05:00) To: [email protected] Subject: Re: [QRPLabs] qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING I have the New PCB with the power supplies on the main board. I will inspect everything again. ?Steve where didyou make connection for the D103 ?? ?I am thinking , mine on top of the PCB? IC101 output to a nearby VDD JP106 hole. ? I am unclear if that is correct,? ain't done it yet. Lee, ?AA7HC ? ?

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