Re: Help - VCC too high

On Wed, May 29, 2024 at 10:59 PM, @Ludwig_DH8WN wrote:

?where did you measure VCC?

Cliff, did you measure with a DMM or did you use only the value from the terminal screen?

73, Ludwig

Re: Wall warts can be fatal to QMX :-(

I've got plenty of buck convertors.  I was trying to complete the project while getting ready to go to FDIM and do a talk.   A perfect example of the folly of "multitasking".  You make more mistakes :-(

Reg

Re: Help - VCC too high

#123118

Yes, thanks Evan.

Show quoted text

On Wed, May 29, 2024 at 5:09?PM Evan Hand via <elhandjr=[email protected]> wrote:

Tony,

There is a file in this link that describes how to test the SMPS modules:
/g/QRPLabs/filessearch?p=name%2C%2C%2C20%2C1%2C0%2C0&q=smps

73
Evan
AC9TU

Re: QMX 170mA draw at 7V with first application of power

#123117

On Thu, May 30, 2024 at 12:15 AM, <corbin.haugen@...> wrote:

Maybe the recommendation for initial smoke test should be 7V limited to 100mA.? If you try to turn the unit on when limited to 100mA, it fails to do so.? This would prevent it from turning on accidentally and causing confusion.

Next, bump up to full power (I set it 1.1A)

Corbin,

A step between would be fine. I limit to 220 mA allows to start the RX mode. The current will decrease to around 90 ... 100 mA.

73, Ludwig

Re: QMX 170mA draw at 7V with first application of power

#123116

Maybe the recommendation for initial smoke test should be 7V limited to 100mA.? If you try to turn the unit on when limited to 100mA, it fails to do so.? This would prevent it from turning on accidentally and causing confusion.

Next, bump up to full power (I set it 1.1A) and if there is anything wrong with the left encoder being stuck or shorted, it would turn on by itself and that problem would then be apparent also.

Just a thought,
Corbin

Re: Help - VCC too high

#123115

Tony,

There is a file in this link that describes how to test the SMPS modules:
/g/QRPLabs/filessearch?p=name%2C%2C%2C20%2C1%2C0%2C0&q=smps

73
Evan
AC9TU

Re: Help - VCC too high

#123114

I agree with JZ, a blown gate on Q106 could account for a shorted PWM correction signal and no ability to control the switcher.

Show quoted text

On Wed, May 29, 2024 at 4:57?PM Tony Scaminaci via <tonyscam=[email protected]> wrote:

Cliff,

The 5V SMPS duty cycle is showing 0% with the ?voltage at 5.11V. The PWM_5V signal is stuck (not toggling), probably in a futile attempt to lower the output voltage. Note the 34% duty cycle on the 3.3V SMPS - the 5V switcher should also have a non-zero duty cycle.

Can you please post the same screen with the input at 10V? Is there any input voltage up to 12V that shows a non-zero duty cycle for the 5V switcher?

Tony

On Wed, May 29, 2024 at 4:40?PM Cliff via <ae5zaham=[email protected]> wrote:
Ludwig,

The QMX will not boot at 7V. 9V will let it boot so the screen shot if with 9V.

As it sits there the 5V varies up and dow a little. If I go to 10V in it varies up 5.8 or so.

73,
Cliff, AE5ZA

On May 29, 2024, at 15:59, DH8WN via <DH8WN@...> wrote:

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Help - VCC too high

#123113

Cliff,

The 5V SMPS duty cycle is showing 0% with the ?voltage at 5.11V. The PWM_5V signal is stuck (not toggling), probably in a futile attempt to lower the output voltage. Note the 34% duty cycle on the 3.3V SMPS - the 5V switcher should also have a non-zero duty cycle.

Can you please post the same screen with the input at 10V? Is there any input voltage up to 12V that shows a non-zero duty cycle for the 5V switcher?

Tony

Show quoted text

On Wed, May 29, 2024 at 4:40?PM Cliff via <ae5zaham=[email protected]> wrote:

Ludwig,

The QMX will not boot at 7V. 9V will let it boot so the screen shot if with 9V.

As it sits there the 5V varies up and dow a little. If I go to 10V in it varies up 5.8 or so.

73,
Cliff, AE5ZA

On May 29, 2024, at 15:59, DH8WN via <DH8WN@...> wrote:

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Help - VCC too high

#123112

Duty cycle =0!

That means the MCU is doing all it can to throttle back the 5V SMPS and is finding it has no control at all.

Possibly one or more damaged transistors on the 5V SMPS module.

I would check Q106 for shorts.

JZ

Show quoted text

On Wed, May 29, 2024, 5:40?PM Cliff via <ae5zaham=[email protected]> wrote:

Ludwig,

The QMX will not boot at 7V. 9V will let it boot so the screen shot if with 9V.

As it sits there the 5V varies up and dow a little. If I go to 10V in it varies up 5.8 or so.

73,
Cliff, AE5ZA

On May 29, 2024, at 15:59, DH8WN via <DH8WN@...> wrote:

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Help - VCC too high

#123111

开云体育

Tony,

Thanks for the input. I can't do what you say until tomorrow and I don't have a scope. I'll report back what I see tomorrow.

Another bit of info, I replaced the PS#1 board with one from another QMX. It worked ok, but the voltage varied quite a bit just sitting there, like .3 or .4 volts. Back in the original QMX it only varies slightly. Seems as if something in the "bad" QMX is causing a varying load. Very odd, IMO.

73,

Cliff, AE5ZA

Show quoted text

On May 29, 2024, at 16:11, Tony Scaminaci via <tonyscam@...> wrote:

Your initial thoughts that Vcc was too high at 6V are confirmed and this is likely why the original 6.3V cap blew.

I think Ludwig is correct, the feedback control loop isn’t working properly. If you have a scope, check the waveform duty cycle at the PWM_5V test point. Also check the DC voltage at the ADC_5V test point which should be 2.5 V. My guess is the ADC test point is 3V or higher. The duty cycle at the PWM test point should be no higher than 56% and most likely, less than 50% because the output voltage exceeds 5V. If the duty cycle is within spec (also shown on the SMPS screen), then there is another faulty component in the switcher circuit.

Tony AC9QY

On Wed, May 29, 2024 at 3:59?PM DH8WN via??<DH8WN=[email protected]> wrote:
Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Help - VCC too high

#123110

开云体育

Ludwig,

The QMX will not boot at 7V. 9V will let it boot so the screen shot if with 9V.

As it sits there the 5V varies up and dow a little. If I go to 10V in it varies up 5.8 or so.

73,

Cliff, AE5ZA

Show quoted text

On May 29, 2024, at 15:59, DH8WN via <DH8WN@...> wrote:

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Wall warts can be fatal to QMX :-(

#123109

This is why I prefer supply nomenclature on schematics be specific such as 3V3 and 5V rather than Vcc and Vdd which are too easily confused.

Show quoted text

On Tue, May 28, 2024 at 11:29?PM Hans Summers via <hans.summers=[email protected]> wrote:

Hi Reg

I should make it clear, somewhere...
Vcc = 5V
Vdd = 3.3V
Vin = the voltage right at the power connector input
+12V = the voltage downstream of the reverse polarity protection and soft on/off power switch. Though identified as?+12V it could of course be other than that, depending on what your Vin is.
This Vcc/Vdd nomenclature appears to be most commonly associated with the 74-series logic in which on the 74xx and 74LSxx TTL (bipolar transistors) logic chips, Vcc was the supply voltage?(c = collector) and was always 5V. On the 74HCxx chips (MOSFETs), Vdd was the supply voltage (d = drain), and was not necessarily 3.3V; but the subsequent most common supply voltage on many digital IC's (MOSFET-based) is now 3.3V so this is what Vdd commonly means. It does all get a bit confusing and even controversial.?

73 Hans G0UPL

On Wed, May 29, 2024 at 3:40?AM Reginald Beardsley via <pulaskite=[email protected]> wrote:
Chris,

Thanks.? ? Neither of the #1? boards shows 5 V on +12? after grounding power on.? The voltage is 1-2 V max.? ?Happily, I have two unbuilt QMX kits I can borrow replacements from.

Is Vcc = Vin?? I've not seen it stated anywhere in the schematics.

Have Fun!,
Reg

Re: Help - VCC too high

#123108

Your initial thoughts that Vcc was too high at 6V are confirmed and this is likely why the original 6.3V cap blew.

I think Ludwig is correct, the feedback control loop isn’t working properly. If you have a scope, check the waveform duty cycle at the PWM_5V test point. Also check the DC voltage at the ADC_5V test point which should be 2.5 V. My guess is the ADC test point is 3V or higher. The duty cycle at the PWM test point should be no higher than 56% and most likely, less than 50% because the output voltage exceeds 5V. If the duty cycle is within spec (also shown on the SMPS screen), then there is another faulty component in the switcher circuit.

Tony AC9QY

Show quoted text

On Wed, May 29, 2024 at 3:59?PM DH8WN via <DH8WN=[email protected]> wrote:

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Help - VCC too high

#123107

Cliff,

it looks like a problem in the control loop.

How and where did you measure VCC?

If really 6 V and more D108 on board #1 must be broken or disconnected. But this isn't the reason for the high VCC. It's only a lack of protection.

Please show a screen shot of Terminal - Hardware tests - Diagnostics. But use only around 7 V input to protect the QMX. And what is VCC in this situation.

73, Ludwig

Re: Question about the Max voltage operation for QMX

#123106

The problem with 13.8V (the normal 12V in a car or shack) comes when transmitting. Limiting the voltage to 12V protects the finals. If you have a perfect antenna 50ohm 0z you may get away with 13.8 volts forever. Since I never have that perfect antenna, I lower to 12V. I blew up a QDX when I was running a big mismatch at 13.8, I forgot to change the tuner when changing bands. The repair took about 30 minutes and cost about $3 in parts. I was running 5w of WSPR for two minutes of key down and two minutes of break and it took quite a few cycles to blow.?
--
Colin - K6JTH?

Re: Question about the Max voltage operation for QMX

#123105

I use a Buck Boost DC from Aliexpress, Input 8 to 36V output 12V between the battery and the QMX.

Re: #qmx wrong inductances for LPF? #qmx

#123104

Start with Zout is not 100 ohms its 50, the antenna.

Steve why add 10 ohms at the input?? ?ELSIE can set the source and
load impedance to the desired value.? All the 10 ohms adds is
insertion loss and will distort the filter.

Generally with Elsie if I use real values and Qs I get result remarkably
close to reality.? By remarkably close if I use 10% caps, and measured
inductance I get what was modeled.? When they differ its due to strays
or component tolerance (or the selected filter is intolerant!) .
I find the TUNE function useful. With that I can inject some manual
Monte Carlo to see how it behaves with part variation.?

To move the cutoff up start with the base filter and trim the value
by a percentage of the original base frequency and the target.
That's only a starting point.?

So software simulation is as much how the user drives it can influence
the result.? GIGO!

RE: FERRITE over the years I've used a metric boat load of it for all manner?
of designs.? ?EVERY TIME I had an error that didn't measure there was an
error either not uniformly wound or under count (+1 turn).

FYI:? if you pinch the winding close rather than uniform a variation of
more than 10% is easily had and I've seen as much as 18% measured
from close to as wide as possible.

Tools that measure I have, AADE LCII (very accurate), ACE LCR,
NanoVNA (I have three), HP4191A impedance analyzer, Daton M250?
LCR bridge.? When they all agree, then the error is elsewhere.

Its very easy to create your own errors.

--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.

Re: Wall warts can be fatal to QMX :-(

#123103

FYI: This device allows one to adjust the voltage (down only) and clean the power coming from various wall warts or computer power supplies. However, the output voltage will be at minimum 2V lower than the input voltage to the device.

see:

--
73
de Roy - KI0ER
Littleton, Colorado USA

Re: QMX 170mA draw at 7V with first application of power

#123102

This seems like a good addition to the QMX wiki.  I also was confused by ~130mA current draw at 7 volts, when there's mention made of "Receive current 80mA".  Of course, I now know better, thanks to this group....
de va3rr

QMX AF Filter Sweep Problem

#123101

New Rev 4 QMX. Receiver was working fine. Transmitter needed some LPF tweaking. Transmitter now fine, but receiver has no sensitivity.

The AF Filter and RF Filter sweeps now look terrible (60-80 dB attenuation).? No obvious solder issues.? I traced through the RF path with an RF signal generator and scope. Looks okay from antenna connector to pins 7 and 9 of IC403.

I think I need to start with the AF sweep problem.? I don't really understand the ADC and audio chain after T401 . I would appreciate advice on how to proceed. As mentioned previously, I have an RF signal generator and a scope. Could easily rig up an AF signal generator.

Thanks and 73,
Steve, N2IC