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Took me a while to find the problem with my just assembled QCX - 20m .. #qcx

regzzz@...
 

Hi all,   Last month I build my first QCX (40m) and I thoroughly enjoyed it. So much that a few weeks after that I ordered an other QCX (20m) and a clock and GPS... hehe

I finished building the new QCX 20m ,  double checked everything before plugin in the power.

As soon as I applied power, LCD back-light was on but no characters, even after adjusting R47.
Then nearly burned my finger as I touched IC11...  so I immediately unplugged power.. 
My first though is I mess up something and now fried something..  grrr...  
Took me a few hours, and I check every solder I did, both sides, check all components..  etc..  looked and the diagnostic information on this site... nothing helped me find the prob.

Then I checked the per-installed surface mount components...  see pic attached and you'll see the problem:




I did not know how to fix this...  Google and Youtube to the rescue...  hehe.

I was able to remove the solder short with the iron and a needle.

Re-applied power and all is well...  :-)

Just tough I'dd share the experience in case it happens to someone else.

Now off to update the firmware to 1.01a..

Cheers all.

 
TAGS:  IC11 Hot, LCD Blank


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73 de Reg  VA2VEC

Gregg Myers
 

Good catch! I’m glad you were able to rescue that short with a hot needle. That was a clever idea and I'll put that one in my future bag of tricks.

73,
Gregg W7GRM

On Sun, Oct 20, 2019 at 3:03 PM regzzz via Groups.Io <regzzz=yahoo.com@groups.io> wrote:
Hi all,   Last month I build my first QCX (40m) and I thoroughly enjoyed it. So much that a few weeks after that I ordered an other QCX (20m) and a clock and GPS... hehe

I finished building the new QCX 20m ,  double checked everything before plugin in the power.

As soon as I applied power, LCD back-light was on but no characters, even after adjusting R47.
Then nearly burned my finger as I touched IC11...  so I immediately unplugged power.. 
My first though is I mess up something and now fried something..  grrr...  
Took me a few hours, and I check every solder I did, both sides, check all components..  etc..  looked and the diagnostic information on this site... nothing helped me find the prob.

Then I checked the per-installed surface mount components...  see pic attached and you'll see the problem:




I did not know how to fix this...  Google and Youtube to the rescue...  hehe.

I was able to remove the solder short with the iron and a needle.

Re-applied power and all is well...  :-)

Just tough I'dd share the experience in case it happens to someone else.

Now off to update the firmware to 1.01a..

Cheers all.

 
TAGS:  IC11 Hot, LCD Blank


--
73 de Reg  VA2VEC

David Wilcox
 

Thanks for the great photo and instructions.... will help a lot of newbies know what to look for.

David J. Wilcox K8WPE’s iPad

On Oct 20, 2019, at 5:57 PM, Gregg Myers <gregg.w7grm@...> wrote:


Good catch! I’m glad you were able to rescue that short with a hot needle. That was a clever idea and I'll put that one in my future bag of tricks.

73,
Gregg W7GRM

On Sun, Oct 20, 2019 at 3:03 PM regzzz via Groups.Io <regzzz=yahoo.com@groups.io> wrote:
Hi all,   Last month I build my first QCX (40m) and I thoroughly enjoyed it. So much that a few weeks after that I ordered an other QCX (20m) and a clock and GPS... hehe

I finished building the new QCX 20m ,  double checked everything before plugin in the power.

As soon as I applied power, LCD back-light was on but no characters, even after adjusting R47.
Then nearly burned my finger as I touched IC11...  so I immediately unplugged power.. 
My first though is I mess up something and now fried something..  grrr...  
Took me a few hours, and I check every solder I did, both sides, check all components..  etc..  looked and the diagnostic information on this site... nothing helped me find the prob.

Then I checked the per-installed surface mount components...  see pic attached and you'll see the problem:

<QRPLabs QCX solder short.JPG>



I did not know how to fix this...  Google and Youtube to the rescue...  hehe.

I was able to remove the solder short with the iron and a needle.

Re-applied power and all is well...  :-)

Just tough I'dd share the experience in case it happens to someone else.

Now off to update the firmware to 1.01a..

Cheers all.

 
TAGS:  IC11 Hot, LCD Blank


--
73 de Reg  VA2VEC

Curt M.
 

Depending on how the traces are routed you may be able to take a dental pick and break the solder joint by scraping a line between where the two areas are bridged. I would evaluate the drawings of the circuit board before I do that just to make sure you aren'ty going to damage something else,

Curt M.

regzzz@...
 

That is a good point Curt,

I did check the manual PCB outlay before I went in there with the Iron,   I tried with just the needle first, and there was too much solder to create a gap while it was cold...  

As you can see from below, the extra solder was creating a short between pin 7 and 8 on IC1.  and when you look at the schematic, it was a short between ground and VDDO thus bypassing C2.





--
73 de Reg  VA2VEC

R. Tyson
 

I built a 40m kit. and then ordered the 20m kit. I checked over the 2 soldered on IC's with a jewellers loupe before starting on the 20m kit - don't know why as there had been no problem with the 40m kit. Glad I did as there was a very thin, like a hair, solder bridge between the first two pins on the same IC as yours - IC11. I got away with a very quick wipe with the fine tip on my soldering iron.

Maybe worth taking a close look at the two surface mount IC's before starting the build on a new board if there is a solder bridge it's easier to get at before mounting the rest of the components.

Reg        G4NFR

geoff M0ORE
 

I bought a module from Banggood a few weeks ago and that had a badly soldered SM chip. Re-soldered and it's now OK. Much prefer to solder my own chips but fully understand why Hans gets them done in the factory and too much hassle to offer two versions, one with chips soldered and one without.


On 21/10/2019 21:01, R. Tyson via Groups.Io wrote:
I built a 40m kit. and then ordered the 20m kit. I checked over the 2 soldered on IC's with a jewellers loupe before starting on the 20m kit - don't know why as there had been no problem with the 40m kit. Glad I did as there was a very thin, like a hair, solder bridge between the first two pins on the same IC as yours - IC11. I got away with a very quick wipe with the fine tip on my soldering iron.

Maybe worth taking a close look at the two surface mount IC's before starting the build on a new board if there is a solder bridge it's easier to get at before mounting the rest of the components.

Reg        G4NFR

_Dave_K0MBT
 

Kudos on the excellent quality of the macro photograph.  On my screen it is a 20x magnification.
--
73
Dave
k0mbt
Ham_Made_Keys

regzzz@...
 

Glad you like Dave,  I took the picture with my iPhone XR,   I was surprised it came out this good. :-)  

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73 de Reg  VA2VEC