QCX-mini batch 2 update


Hans Summers
 

Hi all

Some photos attached, the assembled boards were completed today (see attached). They will now be shipped to me and expected to arrive here in about 2 weeks (taking into account customs clearance and inevitable expected average delays). 

Three important points about the batch 2 boards:

1) The voltage regulator is changed to 78M05 which is a 5V 0.5A regulator with 30V max rating, and is a more robust, less delicate, choice than the 1117-type LDO regulators; it increases my cost but not by much. There's nothing wrong with the first batch 1117 regulators per se but, they are evidently not very tolerant of the slightest abuse and the failure mode is rather unpleasant. 

2) I changed PCB Assembly house - obviously eventually the proof of the pudding will be in the eating - but initial inspection by my associate in Shenzhen has indicated the quality is high. We produced 2,000 boards and all 2,000 were delivered from the board house to my warehouse in one batch, without any manual re-work (recall that we eventually discovered that 3.3% of the 1000 boards in batch 1 were subjected to manual re-work and were delivered 2 days later, and in a few cases the quality of the manual rework was poor). 

3) I am still working on a test jig, see attached pogo.jpg - my aim is to personally test 100% of all PCBs prior to shipment, in addition to an extra visual inspection. There are around 50 pogo pins that make a connection to the board under test. In the next 2 weeks while waiting for the boards to arrive, I am aiming to complete the hardware and software required, that will allow me to comprehensively test every function of the QCX-mini PCBA and the entire signal path, transmit and receive. I am optimistic that the defect rate will be reduced to close to zero in this final QC check. 

73 Hans G0UPL
http://qrp-labs.com



Matt Burge <matt24512@...>
 

Thanks Hans for the information... looking forward to receiving my kit👍


On 26 Jan 2021, at 08:54, Hans Summers <hans.summers@...> wrote:


Hi all

Some photos attached, the assembled boards were completed today (see attached). They will now be shipped to me and expected to arrive here in about 2 weeks (taking into account customs clearance and inevitable expected average delays). 

Three important points about the batch 2 boards:

1) The voltage regulator is changed to 78M05 which is a 5V 0.5A regulator with 30V max rating, and is a more robust, less delicate, choice than the 1117-type LDO regulators; it increases my cost but not by much. There's nothing wrong with the first batch 1117 regulators per se but, they are evidently not very tolerant of the slightest abuse and the failure mode is rather unpleasant. 

2) I changed PCB Assembly house - obviously eventually the proof of the pudding will be in the eating - but initial inspection by my associate in Shenzhen has indicated the quality is high. We produced 2,000 boards and all 2,000 were delivered from the board house to my warehouse in one batch, without any manual re-work (recall that we eventually discovered that 3.3% of the 1000 boards in batch 1 were subjected to manual re-work and were delivered 2 days later, and in a few cases the quality of the manual rework was poor). 

3) I am still working on a test jig, see attached pogo.jpg - my aim is to personally test 100% of all PCBs prior to shipment, in addition to an extra visual inspection. There are around 50 pogo pins that make a connection to the board under test. In the next 2 weeks while waiting for the boards to arrive, I am aiming to complete the hardware and software required, that will allow me to comprehensively test every function of the QCX-mini PCBA and the entire signal path, transmit and receive. I am optimistic that the defect rate will be reduced to close to zero in this final QC check. 

73 Hans G0UPL
http://qrp-labs.com


<top.jpg>
<panel.jpg>
<pogo.jpg>
<Si5351A.jpg>
<bottom.jpg>
<78m05.jpg>


Catherine Hunt
 

Thank you for the update Hans. I’ll look forward to receiving my kit

Cathy M5CAH


Al Holt
 

Hans,
That's good news!  Would you care to comment on how things are progressing with the pre-assembled 'Mini's you and your team are building from the first run of boards?
I'm curious if you all are encountering some of the same issues being reported from the field.

Pogo testing technique looks interesting, but very time consuming to implement. I read a little about it on the Adafruit page. Good luck with your quality control efforts!!

--Al
WD4AH


Mike Besemer - WM4B
 

No.  The pilot is different and requires some fidgeting.

Mike
WM4B

On Jan 26, 2021, at 6:05 AM, Mark Palmer <esperanto@...> wrote:
Is the regulator just a straight swap? Might it be worth replacing the 1117 as a precaution, even though I've added the extra capacitor? 






N3MNT
 

Those boards look great. Pogo testing in an operation like yours is very impressive as is the rapid corrective action and resumption of assembly.
N3MNT
Bob


Richard - N1RBD
 

On Tue, Jan 26, 2021 at 06:57 AM, Al Holt wrote:
Hans,
That's good news!  Would you care to comment on how things are progressing with the pre-assembled 'Mini's you and your team are building from the first run of boards?
I'm curious if you all are encountering some of the same issues being reported from the field.
Along those lines, if a pre-assembed unit from the first run hasn't shipped yet can we request that it be assembled from the new run of boards?


Nigel Evans M0NDE
 

I too am interested in Hans findings with his own workshop mini builds. I did my very best to assemble the mini with care.  I also think the test jig whilst requiring much work for Hans will give him the knowledge every board leaving the shop is in working order.

Nigel M0NDE

On Tue, 26 Jan 2021 at 13:52, Richard <groups.io@...> wrote:
On Tue, Jan 26, 2021 at 06:57 AM, Al Holt wrote:
Hans,
That's good news!  Would you care to comment on how things are progressing with the pre-assembled 'Mini's you and your team are building from the first run of boards?
I'm curious if you all are encountering some of the same issues being reported from the field.
Along those lines, if a pre-assembed unit from the first run hasn't shipped yet can we request that it be assembled from the new run of boards?



--
73 de Nigel Evans
Callsign: M0NDE
QTH: Willington
Locator: IO92fu
http://nigel-m0nde.blogspot.com/



GEO Shop
www.geo-web.org.uk
shop@...
http://www.facebook.com/groupforearthobservation
------------------------------------------------------------------------------


David Poole
 

Hans, is the 78M05 a direct replacement for the 1117 LDO regulator?
I have a Rev 1 board and I see a few differences to the Rev 2 board.
I won my mini in a club competition and have not started the build yet.
Dave
VK5PL


N3MNT
 

The 78m05 is not a direct replacement for the 1117 as the pinout is different.


Al Holt
 

On Tue, Jan 26, 2021 at 08:58 AM, Nigel Evans M0NDE wrote:
 ...the knowledge every board leaving the shop is in working order.
Reminds me of a TV engineer's (me) retort when asked about color balance issue or signal glitch, "the problem's fine leaving here....." 

(tongue firmly planted in cheek) 

--Al


ohwenzelph
 

The photos show 2nd gen board with 3rd line on the OPA2277 chips as 97ZXK and seems to be the same on each of the op amps. On my first generation board there are 6 characters in the 3rd line, instead of 5, and the set of characters is different on each chip. Seems odd on the first generation board. Might this have anything to do with the first gen op amp problems?


mike/w1mt
 

What's blob on the LM4562 (IC5) op amp in the top.jpg pic?

mike/w1mt


On Tue, Jan 26, 2021 at 5:28 AM Matt Burge via groups.io <matt24512=yahoo.com@groups.io> wrote:
Thanks Hans for the information... looking forward to receiving my kit👍


On 26 Jan 2021, at 08:54, Hans Summers <hans.summers@...> wrote:


Hi all

Some photos attached, the assembled boards were completed today (see attached). They will now be shipped to me and expected to arrive here in about 2 weeks (taking into account customs clearance and inevitable expected average delays). 

Three important points about the batch 2 boards:

1) The voltage regulator is changed to 78M05 which is a 5V 0.5A regulator with 30V max rating, and is a more robust, less delicate, choice than the 1117-type LDO regulators; it increases my cost but not by much. There's nothing wrong with the first batch 1117 regulators per se but, they are evidently not very tolerant of the slightest abuse and the failure mode is rather unpleasant. 

2) I changed PCB Assembly house - obviously eventually the proof of the pudding will be in the eating - but initial inspection by my associate in Shenzhen has indicated the quality is high. We produced 2,000 boards and all 2,000 were delivered from the board house to my warehouse in one batch, without any manual re-work (recall that we eventually discovered that 3.3% of the 1000 boards in batch 1 were subjected to manual re-work and were delivered 2 days later, and in a few cases the quality of the manual rework was poor). 

3) I am still working on a test jig, see attached pogo.jpg - my aim is to personally test 100% of all PCBs prior to shipment, in addition to an extra visual inspection. There are around 50 pogo pins that make a connection to the board under test. In the next 2 weeks while waiting for the boards to arrive, I am aiming to complete the hardware and software required, that will allow me to comprehensively test every function of the QCX-mini PCBA and the entire signal path, transmit and receive. I am optimistic that the defect rate will be reduced to close to zero in this final QC check. 

73 Hans G0UPL
http://qrp-labs.com


<top.jpg>
<panel.jpg>
<pogo.jpg>
<Si5351A.jpg>
<bottom.jpg>
<78m05.jpg>


Fred Spinner
 

The package Hans picked for that Rev 2 is the more common TO-252 for the 78m05, but you can order a TO-223 package as well with slightly poorer thermal characteristics.  (Which are fine in this application.) The issue is that the 1117 regulator is based on the LM317 pinout and not the 7805 in both packages, so instead of input ground output on the new regulator the version 1 layout is ground output input. So there are ways to do it but none are pretty or drop in. 

Now compared to replacing all of the 5v devices and the display later on which in my disgruntled (apparently, but I think all of you are too nice...) opinion will eventually happen to all of the first thousand units in actual field use, it's easier to do the retrofit. 

I have not done mine yet because it has to be a Mouser or Digi-Key order and I have been busy with family emergency and other projects and kits that don't need to be fixed first.

Again adding in that Digi-Key order made this an expensive and annoying project, but others are giving out five star reviews, so I won't rain on the parade any more. 



On Tue, Jan 26, 2021, 7:59 AM ohwenzelph via groups.io <Ohwenzelph=yahoo.com@groups.io> wrote:
The photos show 2nd gen board with 3rd line on the OPA2277 chips as 97ZXK and seems to be the same on each of the op amps. On my first generation board there are 6 characters in the 3rd line, instead of 5, and the set of characters is different on each chip. Seems odd on the first generation board. Might this have anything to do with the first gen op amp problems?


va3rr
 

I'm guessing the circuit board fabricator was using up stock already on hand? Therefore the different date codes. It is strange that different date codes would show up on the same board, assuming automated parts placement.

I bought some OPA2277 on Aliexpress - they all had the same date code (69XXK), but came loose in a plastic bag :^(

On Tue, Jan 26, 2021 at 09:58 AM, ohwenzelph wrote:
The photos show 2nd gen board with 3rd line on the OPA2277 chips as 97ZXK and
seems to be the same on each of the op amps. On my first generation board
there are 6 characters in the 3rd line, instead of 5, and the set of
characters is *different* on each chip. Seems odd on the first generation
board. Might this have anything to do with the first gen op amp problems?


Richard - N1RBD
 

On Tue, Jan 26, 2021 at 10:21 AM, Fred Spinner wrote:
 
Again adding in that Digi-Key order made this an expensive and annoying project, but others are giving out five star reviews, so I won't rain on the parade any more. 
 
I wound up spending about 20% of what I paid for the kit on retrofit parts.  $5 for a batch of capacitors for the power regulator issue and another $10  for a replacement Q5 that was cracked.  Not a big deal, but still money I shouldn't have had to spend.


Hans Summers
 

Gentlemen,

There are a lot of happy users of the QCX-mini, and overall the new kit has generated a lot of excitement. At the same time, there are also some people who have had problems due to shortcomings in the production of the first batch of QCX-mini kits, which is a great disappointment to me. The issues fall into three categories:

1) PCB assembly defects (3.3% of kits were subjected to manual re-work, of which a proportion of those were done badly).

2) Delicate nature of the voltage regulator, though I destroyed precisely ZERO during my R&D for this product, it is evidently much less tolerant of abuse than the 7805 in the QCX+ kit. It isn't easy to destroy a 7805 but apparently a '1117 type regulator is much easier to kill, and when it dies, it takes down other downstream components with it. 

3) Reports of defective op-amps, though we don't know what percentage of people have had a problem. 
(On this topic - another thing I forgot to mention is that I have managed to obtain a sample strip of 100 op-amps from the same reels that were used in the batch 1 PCB assembly, and they should arrive at my QTH in the next couple of days. These I will test carefully. If they are OK it would perhaps indicate that there was some issue in the assembly factory, such as heating to the wrong temperature or duration etc. We shall see).

I am doing my very best to reduce issues in all three categories, in the 2nd batch of QCX-mini kits. I started this thread to give both an update on timelines for the 2nd batch, and also to show you exactly how I am making the improvements. 

May I suggest that anyone who feels disgruntled and in need of compensation should contact me off-list and I will willingly arrange it for you to your satisfaction, on a case by case basis. 

73 Hans G0UPL
http://qrp-labs.com


Ted 2E0THH
 

On Tue, Jan 26, 2021 at 03:21 PM, Fred Spinner wrote:
Now compared to replacing all of the 5v devices and the display later on which in my disgruntled (apparently, but I think all of you are too nice...) opinion will eventually happen to all of the first thousand units in actual field use, it's easier to do the retrofit. 
 
Fred, where exactly is your evidence for this? There are over a 1000 of these out in the field and you are seeing a handful of failures.
We used to get our knuckles rapped for making such rash assumptions.
Bad science mate.

Ted


Mike Besemer - WM4B
 

If you'd have asked around, someone on the list could have probably supplied the parts you needed for free.  If not, I'm sure Hans would have sent them to you.  The decision to come out-of-pocket was yous alone.  I'll send you 15 bucks if it will make you happy.

Mike
WM4B

On Jan 26, 2021, at 11:28 AM, Richard <groups.io@richard.dervan.net target=_blank>groups.io@richard.dervan.net> wrote:
On Tue, Jan 26, 2021 at 10:21 AM, Fred Spinner wrote:
 
Again adding in that Digi-Key order made this an expensive and annoying project, but others are giving out five star reviews, so I won't rain on the parade any more. 
 
I wound up spending about 20% of what I paid for the kit on retrofit parts.  $5 for a batch of capacitors for the power regulator issue and another $10  for a replacement Q5 that was cracked.  Not a big deal, but still money I shouldn't have had to spend.


Fred Spinner
 

Oh come on man!  You don't use a 15V absolute max regulator at 13.8V.  You don't need a production test engineer like me to tell you that.  There I said it! 

In an actual commercial product those first boards would have been recalled and scrapped. 

I get that Hans probably overlooked that regulator when doing the new design for cost and I might have also.  It's a regulator so it should have been a no brainer. 

But to say it's "fine going on" is doing a disservice to the original thousand customers.  It's not.  Replace the damned regulator or have it pop at some point.  I am done arguing about that.  Or run your mini at 10V.  Don't say that I didn't tell you so.   If you don't believe me, go look into the Arduino Nano issues at 12V with the same regulator.   At least those are only $3 when they go. 

The other issues were the production facility, likely, or even a bad reel of parts.  I did post a picture of my LM4562 with almost no markings on it, too.  It looked like it was ground down and relabelled.  I have never seen a factory part with that light of marking in thousands of parts.  I probably am just going to go in and replace all of them as my time is worth more than $7 worth of parts.  Plus I want the thing to work as designed for hundreds of hours.   I have the skills and tools to do it, but not really the eyesight anymore.   If I break out the hot air, I only want to do it once. 

I should add that when I have time again to do all of that it should be a fine rig for what it is even with 20% more cost added.. But that is not the point, really, as many of us would have waited this out if we had any idea this would happen. 

By the way, a LM340T-5 in a TO-223 package will also work the same way with the same pinout changes at a dollar US more, and I should also add that the TO-223 case in a M05 is only available from TI and is actually called a ua78M05.

It might also be possible to use a 78L05 leaded part but Hans would probably need to inform us of the current draw of the 5V bus.  If it's less than say 75 mA total the 100 mA device might work.



On Tue, Jan 26, 2021, 10:23 AM Mike Besemer - WM4B <mwbesemer@...> wrote:
If you'd have asked around, someone on the list could have probably supplied the parts you needed for free.  If not, I'm sure Hans would have sent them to you.  The decision to come out-of-pocket was yous alone.  I'll send you 15 bucks if it will make you happy.

Mike
WM4B
On Jan 26, 2021, at 11:28 AM, Richard <groups.io@richard.dervan.net target=_blank>groups.io@richard.dervan.net> wrote:
On Tue, Jan 26, 2021 at 10:21 AM, Fred Spinner wrote:
 
Again adding in that Digi-Key order made this an expensive and annoying project, but others are giving out five star reviews, so I won't rain on the parade any more. 
 
I wound up spending about 20% of what I paid for the kit on retrofit parts.  $5 for a batch of capacitors for the power regulator issue and another $10  for a replacement Q5 that was cracked.  Not a big deal, but still money I shouldn't have had to spend.