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Re: QMX+ Filter Cascading Question

 

Thanks Stan.? Actually those first two sentences are the lightbulb on how to use the filters!? Much appreciated.
?
N4TTU - TL
Re: qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING

 

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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?

-------- Original message --------
From: Stan Dye <standye@...>
Date: 9/19/24 10:44 PM (GMT-05:00)
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)
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
Re: qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING

 

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
Re: 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)
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
Re: QMX+ V2 - I've killed it

 

Since you both heard a 'crackle':
I think about the only thing that could crackle with movement of the QCX in receive mode is a mostly direct short between the input 12V and ground.? This could come from the board flexing a bit and something on the board contacting the chassis (or similar mechanical movement).? I would first visually inspect very carefully with board in chassis to see what could possibly touch where it is not supposed to. Current flow for such a short would go mainly through Q105 and Q103, possibly frying one or both of them.? It would be reasonably easy to check the +12V rail at one of the power jumper blocks, or better at the input and output of Q105 when you try to power on.? If you see a good 12V at all of those spots, the problem is elsewhere - but from what you are saying, it's likely in that area of the circuit.
Re: qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING

 

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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)
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
Re: QMX (not-plus) power issue

 

By the way, I will accept the possibility that the meter might need calibration! It's literally brand new, out of the box, and it's a cross-needle type with what look to be calibration screws under the needle display. If we think we can trust the diagnostic's idea of what the power output is (even if it's not what it should be on a given band), I will use that as my standard to calibrate and eliminate one mystery!

On Thu, Sep 19, 2024, at 21:19, Michael - WD0OM wrote:
A couple of weeks ago, I think, I brought up an issue I'd seen with my QMX low-band (20-80), where I was only getting about 1.2W out on 20 meters.

Today, I decided to run some tests using a new power meter and dummy load, and also to see if maybe I'd set a setting wrong.

The results were a little surprising, and probably point to some hardware fault, and not a setting problem. To double-check that theory, I did a factory reset and a firmware upgrade, and received the same results.

I have both narrated video of the power meter, and screen recordings of the terminal app, that I can edit together if they would be useful. I had been thinking of terms of posting a YouTube video about "fixing it" but then, of course, I was not able to fix it!

(That said, I may at some point do a YouTube video guided tour of the Terminal App!)

What I'm seeing when I hit the 'T' key in the Diagnostics screen:

Input voltage looks steady at 11.7
SMPS 3.3V shows 3.3V, 5V shows 5V, Bias SMPS shows 30mA as does PIN Bias

For all of these -- and this may be the hint -- the transmitter voltage shows 10.2 transmitting, 0.6 idle

80m: Diagnostics show 4.7W, power meter shows 2.0
60m: Diagnostics show 5W, power meter shows 3
40m: Diagnostics show 4.3W, power meter shows 2.5
30m: Diagnostics show 2.5W, power meter shows 1.25
20m: Diagnostics show 1.2-1.3W, power meter shows 0.5

Where is the most likely place to look for both the shortfall relative to the meter, and the shortfall relative to general expectations of 5W as opposed to 1.2?

Thanks!
Michael WD0OM
QMX (not-plus) power issue

 

A couple of weeks ago, I think, I brought up an issue I'd seen with my QMX low-band (20-80), where I was only getting about 1.2W out on 20 meters.

Today, I decided to run some tests using a new power meter and dummy load, and also to see if maybe I'd set a setting wrong.

The results were a little surprising, and probably point to some hardware fault, and not a setting problem. To double-check that theory, I did a factory reset and a firmware upgrade, and received the same results.

I have both narrated video of the power meter, and screen recordings of the terminal app, that I can edit together if they would be useful. I had been thinking of terms of posting a YouTube video about "fixing it" but then, of course, I was not able to fix it!

(That said, I may at some point do a YouTube video guided tour of the Terminal App!)

What I'm seeing when I hit the 'T' key in the Diagnostics screen:

Input voltage looks steady at 11.7
SMPS 3.3V shows 3.3V, 5V shows 5V, Bias SMPS shows 30mA as does PIN Bias

For all of these -- and this may be the hint -- the transmitter voltage shows 10.2 transmitting, 0.6 idle

80m: Diagnostics show 4.7W, power meter shows 2.0
60m: Diagnostics show 5W, power meter shows 3
40m: Diagnostics show 4.3W, power meter shows 2.5
30m: Diagnostics show 2.5W, power meter shows 1.25
20m: Diagnostics show 1.2-1.3W, power meter shows 0.5

Where is the most likely place to look for both the shortfall relative to the meter, and the shortfall relative to general expectations of 5W as opposed to 1.2?

Thanks!
Michael WD0OM
Re: Winding toroids with a chopstick?

 

This subject seemed exhaustive.? After reading all the points made, I've almost decided on three best practices to use for winding a toroid:
  1. Wind a larger toroid with a small vise.
  2. Wind a small toroid on a chopstick held in a small vise.
  3. Wind with a small polished plastic crochet hook when it's decided to use a crochet hook.
  4. Follow directions about winding multi-filar coils, coils with taps or binocular forms.
  5. Always stop to consider which direction to wind onto the toroid so as to orient it onto a circuit board, match solder points and the planned vision.
  6. And, never underestimate other's imaginations!

I am impressed with your skills.


On Tuesday, September 17th, 2024 at 19:53, Karl via groups.io <karlshumaker@...> wrote:

Great idea! I used crochet hooks on the QMX+ toroids and they wound fast anf tight.
--
73
Karl
KI4ZUQ
Re: QMX+ V2 - I've killed it

 

I can not get the USB to be recognized .
?
Hope the MCU is not dead.
Re: QMX+ V2 - I've killed it

 

Another possibly "obvious" question -- the screen doesn't come up, but does the terminal app?

There's an awful lot of diagnostic available IF you can get to the terminal app.

On Thu, Sep 19, 2024, at 20:02, harleyleenuke wrote:
I did exactly the same thing. Running it for a few hours. I tilted the rig up to get a better view of the screen and heard a crackle.? Then it shut down and will not power up.
Checked the dc plug? for shorts and solid connection. No issues found.
My testing so far is Pressing th Power button shows 22 ma current draw, But the rig does not start up.
?
Hope you and I get get it working,? Me too.
?Lee
AA7HC
?
Re: QMX+ V2 - I've killed it

 

I did exactly the same thing. Running it for a few hours. I tilted the rig up to get a better view of the screen and heard a crackle.? Then it shut down and will not power up.
Checked the dc plug? for shorts and solid connection. No issues found.
My testing so far is Pressing th Power button shows 22 ma current draw, But the rig does not start up.
?
Hope you and I get get it working,? Me too.
?Lee
AA7HC
?
Re: 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
Re: QMX+ V2 - I've killed it

 

Thanks both - yes, it’s out of the case - no shorts or problems around the power socket. The issue is the same out of the case.
?
The plug is actually a good fit so I’m not sure why it happened. The rig was just in CW rx at the time without a key plugged in. ?
Re: QMX+ V2 - I've killed it

 

开云体育

Hi Steve;

Can you slide the board out of the case and then check to see if the short is still present?

73, Steve, N3SB?

-------- Original message --------
From: Steve MW0KST <stevedavies77@...>
Date: 9/19/24 8:10 PM (GMT-05:00)
Subject: [QRPLabs] QMX+ V2 - I've killed it

After successfully building and tuning my QMX+ (V2 PCB), after a day's use I've done it again and blown something up! I managed to accidentally 'wiggle' the 12V connector with the radio on while leaning over it and trying to plug in a PC monitor (to something else!) - in other words, I was being careless.
?
The rig was connected to a power speaker, so a few loud crackles from that, then it was dead.?Now when I reconnect to a current limited PSU, pressing the on switch on the top encoder causes the supply voltage to short to ground somewhere. So something's blown that shorts the 12V line - I think.
?
With the 12V supply shorting as soon as I press the 'on' button, nothing powers up at all - it's completely dead.
?
No signs of damage or burnt components found, tracks all look ok and no familiar burnt plastic smell. I've checked all the diodes and components around the integral SMPSUs - all seem ok.?
?
If anyone has any pointers on what to look out for, any info. on what to check next would be appreciated!
?
Many thanks,
?
Steve MW0KST
?
?
Re: Solder iron tip recommendations

 

Any of the small chisel tips seems best for me. I find the the very pointed ones do not supply enough heat over a wide area. But if you're working on tiny IC legs then use them, otherwise chisel tips do most everything else. YMMV.
Re: QMX+ V2 - I've killed it

 

At the risk of being suuuuuper obvious, I'd check that 12V connector that wiggled when you leaned over! If it were me, my first thought would be to wonder if one if the solder joints on the 12V connector were all solid to begin with. I don't think they're supposed to wiggle all that much!

Michael WD0OM

On Thu, Sep 19, 2024, at 19:10, Steve MW0KST wrote:
After successfully building and tuning my QMX+ (V2 PCB), after a day's use I've done it again and blown something up! I managed to accidentally 'wiggle' the 12V connector with the radio on while leaning over it and trying to plug in a PC monitor (to something else!) - in other words, I was being careless.
?
The rig was connected to a power speaker, so a few loud crackles from that, then it was dead.?Now when I reconnect to a current limited PSU, pressing the on switch on the top encoder causes the supply voltage to short to ground somewhere. So something's blown that shorts the 12V line - I think.
?
With the 12V supply shorting as soon as I press the 'on' button, nothing powers up at all - it's completely dead.
?
No signs of damage or burnt components found, tracks all look ok and no familiar burnt plastic smell. I've checked all the diodes and components around the integral SMPSUs - all seem ok.?
?
If anyone has any pointers on what to look out for, any info. on what to check next would be appreciated!
?
Many thanks,
?
Steve MW0KST
?
?
QMX+ V2 - I've killed it

 

After successfully building and tuning my QMX+ (V2 PCB), after a day's use I've done it again and blown something up! I managed to accidentally 'wiggle' the 12V connector with the radio on while leaning over it and trying to plug in a PC monitor (to something else!) - in other words, I was being careless.
?
The rig was connected to a power speaker, so a few loud crackles from that, then it was dead.?Now when I reconnect to a current limited PSU, pressing the on switch on the top encoder causes the supply voltage to short to ground somewhere. So something's blown that shorts the 12V line - I think.
?
With the 12V supply shorting as soon as I press the 'on' button, nothing powers up at all - it's completely dead.
?
No signs of damage or burnt components found, tracks all look ok and no familiar burnt plastic smell. I've checked all the diodes and components around the integral SMPSUs - all seem ok.?
?
If anyone has any pointers on what to look out for, any info. on what to check next would be appreciated!
?
Many thanks,
?
Steve MW0KST
?
?
Solder iron tip recommendations

 

I am about to start on a QDX, followed closely by a QMX, then a QMX+. I have a Circuit Specialists 60W adjustable temp iron (similar to a Hakko) and a variety of tips to choose from. What have you found to be the best tips type and size for building these kits?
73,
Steve AK0M
Re: qmx+ SCHEMATIC QUESTION hELP UNDERSTANDING

 

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?


-------- Original message --------
From: harleyleenuke <vfrank59@...>
Date: 9/19/24 6:51 PM (GMT-05:00)
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
?
?
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