Is the short on the main board with ps units and control board removed?
If so, see this post, a couple of people have had this issue recently.?
Also check the metal screw head, make sure it is not touching adjacent components. And I would check carefully for bridged solder pads, particularly anywhere near you installed components.
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Re: QMX SMD assembly defect
Finished my QMX+ today and is was not powering up.
The diode on the backside of the 3.3V module had one pad ripped away and was 90¡ã rotated.
As it looks to me, the pin is not bend enough to allow the 90¡ã rotation. Seems to me that this already happended during the soldering process. Luckily I had spare boards ordered with the kit, just in case...
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Re: Seeking Help with QMX Kit Issues
Hello Eddie.
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Ludwig's suggestion to look at the WIKI doc is spot on.
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I'd check the ohms continuity between ground and each of the VCC and VDD rails first. Remove the SMPS boards boards before doing this and do not apply power or have any other cables or keys attached.
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If too low or especially if showing close to shorts then one or more components on the? main PCB have failed. Tracking those down is difficult. There are several threads where advanced operators have tracked down one or more failed components. Hard and amazing analysis and rework.
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Or, you could contact Jeff Moore for his excellent repair service. Query him at QRZ for his private email address. He revived my QMX+ Rev 1 quickly. I subsequently blew up that one while probing poorly with temperature sensors. The standalone SMPS board checks led to finding one was toast and that one of the rails was shorted on the Main PCB?
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I opted to purchase a 2nd QMX+, a Rev 2, assembled it very carefully and I am back on the air. Now have a component donor main PCB board for future fumbles. :)
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73 GREG KI4NVX?
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Re: QMX+ build: figuring things out? Maybe.
There's really not enough room. It's pretty crowded, and there are surface-mount caps right near it. I have thought about it, and might give it a second look when I come back to it.
Michael WD0OM
On Thu, Oct 3, 2024, at 08:55, Daniel Conklin wrote:
You can probably just solder it on top of the hole.
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73, Dan - W2DLC
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Just completed my QMX+ build. ?It wouldn't boot up. ?I removed the front panel board, SMS boards and the GPS board. ?And after much investigation I found that Vdd is shorted to ground.
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After hours of inspection with a jewelers loupe, it is not a soldier whisker that I can see. ?
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Any Suggestions?
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all the best, ?
Scott. ? KO4NLM
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Re: Easy removal of broken BNC jack on QCX-mini
On the smaller parts, I've found it cleans up very nicely with flux/solder braid and isopropyl alcohol.
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73, Mike KK7ER
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Hi Hans,
on are some references to ... but it seems that it does not exist ...
Cheers,
Torsten
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vy 73 de Torsten | DB2TE
/"\ ASCII Ribbon Campaign
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X www.asciiribbon.org
/ \
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Hi Hans,
on are some references to ... but it seems that it does not exist ...
Cheers,
Torsten
--
vy 73 de Torsten | DB2TE, formerly DO4TE
/"\ ASCII Ribbon Campaign
\ / Against HTML Mail
X www.asciiribbon.org
/ \
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Re: Seeking Help with QMX Kit Issues
Hello Eddie
following the link in my former post you will find information how to test the SMPS boards and the mainboard.
73 Ludwig
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Re: QMX+ build: figuring things out? Maybe.
You can probably just solder it on top of the hole.
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73, Dan - W2DLC
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Re: Seeking Help with QMX Kit Issues
Hi Bruce,
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I certainly agree with you now! I¡¯ve definitely learned my lesson the hard way. I just hope no one else tries to be a hero and attempts to save their boards the way I did¡ªit could save them a lot of disappointment.
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Thanks for the insight!
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73,
Eddie W2FTL
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Re: Seeking Help with QMX Kit Issues
Hi Ludwig,
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Thanks again for the link! I did take a look at the document and followed the steps for troubleshooting the SMPS boards using the terminal. Unfortunately, both of my assembled QMX boards only consume power when I press the left encoder button, but they immediately stop drawing any power as soon as I let go.
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I¡¯ve closely inspected both boards for any signs of physical damage, like burned components, but everything looks clean. I¡¯m concerned that the SMPS boards from Kit #1 were damaged when I accidentally applied 30V, and when I placed them into Kit #2 (which was working fine), they might have sent too much voltage to the processor, potentially killing it. It¡¯s really disheartening, as now I might have two damaged kits¡ªor, at the very least, a lot of spare parts.
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If you have any other suggestions, I¡¯d really appreciate them!
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73,
Eddie W2FTL
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Gwen:? I run all of my power supplies to a buck-boost converter set to 12.0V (also settable to 9.0V), to run my QDXs/QMXs. ?
It will tame pretty much any DC power you care to attach to it.? I haven't run into RFI issues.??
73, Don N2VGU
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Re: QMX mid-band - back from the dead
Yep, it's tight alright. In the photo, the screw is already shoved as far clear as it can possibly go.
Still, it worked out ok in the end so I'm a happy camper. It's my second QMX build. The first was a rev 1 which is still running well.?
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Re: QMX mid-band - back from the dead
I've built a QMX HB and 2 QMX+ units. In all three I found the screw head to be too close for comfort to that nearby chip.
I simply filed a flat on the screw head right down to almost the ends of a pair of the Phillips head slots. Used a hand file for two then remembered I had a nice Dremel tool and used a medium coarse sanding drum for the third. That last one took about 2 minutes going carefully.?
You can also shift the screw body a bit away from the IC when doing the final snug down of the screw/washer/nut. Hold the screw head with a screwdriver and tighten the nut carefully with your fingers or a small pair of pliers while adjusting the position of the washer over the BS170's. No need to use a lot of torque!?
On Thu, Oct 3, 2024 at 6:23 AM, Ronan Cantwell <ronancantwell@...> wrote:
My mid-band QMX (rev 4) is finally back up on its feet and running nicely after a few repairs. I posted a thread a while back with the initial fault(s) and progress with its diagnosis / repair.
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To cut a long story short, a fault on one of the PSU boards took out a few of the ICs on the main board. After fixing the PSU board (faulty zener), I went about ordering replacements for the 5351 and IC's 501, 502 and 503. These were all fitted, along with a fresh set of BS170's and a quick rewind ?of transformer T501, just in case. The end result is a fully working radio that puts out a minimum of 5W on all bands running on a 12V supply.?
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Now for a quick heads-up:
There was one small issue in the repair. The 74ACT08 chips that I ordered from Farnell were a tiny bit too long for the tight space on the board. The metal screw for the BS170 retaining washer prevented the IC from aligning properly with its pads. I ended up having to sand the body of the chip down very slightly in order that it would fit the space. The chips I ordered were manufactured by ONSEMI - part number MC74ACT08DG. They are the correct package and pin spacing but the chip body is just that tiny bit too long for the available space without modification.
Here's a photo of the shortened chip in place, showing the clearance between it and the screw.?
Hope this helps someone who may have similar issues with their radio. It's a great little box and I'm glad it's back in action!?
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Cheers,?
Ronan
MM0IVR?
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I haven't had any problems with my PD power bank and trigger. I don't use a trigger cable, but a separate trigger card witha switch that will give me about 8.7 vil6ts or 11.7 volts. Just make sure to plug the trigger into the battery first, then into the radio.
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73, Dan - W2DLC
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QMX mid-band - back from the dead
My mid-band QMX (rev 4) is finally back up on its feet and running nicely after a few repairs. I posted a thread a while back with the initial fault(s) and progress with its diagnosis / repair.
?
To cut a long story short, a fault on one of the PSU boards took out a few of the ICs on the main board. After fixing the PSU board (faulty zener), I went about ordering replacements for the 5351 and IC's 501, 502 and 503. These were all fitted, along with a fresh set of BS170's and a quick rewind ?of transformer T501, just in case. The end result is a fully working radio that puts out a minimum of 5W on all bands running on a 12V supply.?
?
Now for a quick heads-up:
There was one small issue in the repair. The 74ACT08 chips that I ordered from Farnell were a tiny bit too long for the tight space on the board. The metal screw for the BS170 retaining washer prevented the IC from aligning properly with its pads. I ended up having to sand the body of the chip down very slightly in order that it would fit the space. The chips I ordered were manufactured by ONSEMI - part number MC74ACT08DG. They are the correct package and pin spacing but the chip body is just that tiny bit too long for the available space without modification.
Here's a photo of the shortened chip in place, showing the clearance between it and the screw.?
Hope this helps someone who may have similar issues with their radio. It's a great little box and I'm glad it's back in action!?
?
Cheers,?
Ronan
MM0IVR?
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Re: Seeking Help with QMX Kit Issues
Fault finding by substitution is a risky process in power stages
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Re: Seeking Help with QMX Kit Issues
Hello Eddie,
please ready this document from QRP Labs Wiki. 73 Ludwig
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Exactly as I found. ACCU keyer built soon after I got my licence, auto character space was not enabled. And with the QMX , I send gibberish with auto character enabled and Iambic A. Very difficult to change well established habit. The current challenge is to master my Vibroplex bug, and not send gibberish. Rich
On Thu, 3 Oct 2024 at 9:08, Steve G4EDG via groups.io <g4edg@...> wrote: Try changing from IAMBIC A to IAMBIC B or vice versa. We tend to learn keyer habits very early on in our CW careers and any change in set up can make you send garbage and be unable to understand why!
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The same goes for having Auto Character Spacing switched on or off.
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Maybe be also check the dot dash ratio...mine feels right at 53...Your milage WILL vary :)
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I started off with a WB4VVF ACCU keyer (designed in the early 70s) which seemed to be the forerunner of IAMBIC B....thank goodness, and not Curtis A or some other long forgotten mode.
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73 Steve G4EDG?
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Dirk
Daniel Conklin
Donald S Brant Jr
Bruce Akhurst
Rich Collins