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[help] Only noise being seen while IQ balance / phase lo / phase hi.


Jose Tent
 

Thank you Don.  I believe I have formed an attachment to it now.   And...I still don't understand every thing, but I understand a great deal more.  

I'm really looking forward to the QSX comming out.   If the level of quality, innovation and low price stays the same as QCX, it's gonna be great !  I'm also tempted to buy the new QCX+ and building a 20m version as well....

Thanks again all. 


Don VE3IDS
 

Jose

That's great news, you will no doubt value and enjoy this radio more as you have built and learned how it works as you successfully repaired it. Congrats, well done!

73 Don ve3ids


On Thu., Jun. 4, 2020, 3:58 p.m. Jose Tent, <ksaito2@...> wrote:
Got the C22 today in the mail.   Installed it during lunch hour. (wink wink)  (Clearing the solder out of the hole was PITA)  

It's working !    I can align the QCX now !

!!!!   THANK YOU FOR ALL THAT HELPED !!!!


Jose Tent
 

Got the C22 today in the mail.   Installed it during lunch hour. (wink wink)  (Clearing the solder out of the hole was PITA)  

It's working !    I can align the QCX now !

!!!!   THANK YOU FOR ALL THAT HELPED !!!!


Jose Tent
 

As you say in your later post C22 should be infinite resistance so that turning the volume control should have no effect on IC10 voltages.
I guess the fact that it did is a good confirmation that C22 was bad then.  

I'll source the C22 and will report back !!   Want to thank everyone for their elmer'ing.   

I guess I have to really learn CW and buy a keyer !  (I have every thing else from antenna, tuner, to a 12v power source)

P.S. Anyone know a cheap iambic keyer they recommend or are willing to get rid of for 50$ or so ?


Alan G4ZFQ
 

Jose

   Voltage top of R37 (IC10 pin 5) :     0.93v (@low Vol)    / 2.36v (@med Vol)    / 2.98v (Full vol)
   Voltage bottom of R37 (C22)     :      0.8 V                    / 1.72v                     /   2.47v
As you say in your later post C22 should be infinite resistance so that turning the volume control should have no effect on IC10 voltages.
(The confusion about it's polarity is because originally this capacitor was an electrolytic. Most advisors will be using the schematic which shows it as an electrolytic.)

IC10 voltages are now acceptable.
Testing C22 after removal and, as you say, damaging it can be no indication of it's state when installed. It may well have been stressed if pushed into it's holes too hard.

Replace it and start using your CQX!

73 Alan G4ZFQ


Jose Tent
 

If you clip the top lead of R37, that should separate R37 and C22 so you can do resistance checks of both without disturbing the board joints at this time. The cap should have infinite resistance. 
Didn't see this until I actually took out the C22. Capacitor broke apart.  I tested what was left and I seem to have infinite resistance.

Now I'm confused.  I'm wondering if it was really C22. 


Jose Tent
 

OK.   Took out c22. 

Voltage on IC10 has returned  closer to the expected value. 

    Measured voltage for IC10 are:   pin  1  ~ 8   :   5.90 / 5.93 / 5.93 / 0  ==  6.08 / 5.90 / 5.93 / 11.87    (Volts) 
    Manual indicates :                       pin  1  ~ 8   :   5.8    / 5.8   / 5.8   / 0  ==  4.2  / 3.94  / 5.83 / 11.67    (Volts) 

Pin 5,6 has a higher voltage than expected.   But, it's not as bad as the 12 volts I was seeing on pin 1,2,3. 

I have to go source a 10uF cap now.  With all the small electronics stores closed around NJ, I guess I have to go to digikey ?  I don't imagine Homedepot sells these.

Will report back when I get it in. 


Don VE3IDS
 

Jose
If you clip the top lead of R37, that should separate R37 and C22 so you can do resistance checks of both without disturbing the board joints at this time. The cap should have infinite resistance. 

Don ve3ids


On Sun., May 31, 2020, 9:06 p.m. Jose Tent, <ksaito2@...> wrote:
Mutimeter:
    I'm using a 10030S Southwire digital multimeter.  Cheap, but not the absolute bottom of the barrel either.   

R37 Voltage REDUX:
I rechecked the voltage on R37 today again.   Well, the voltage on the top connected to IC10 Pin 5 is always higher by a bit through the swing of the volume pot. 
   Voltage top of R37 (IC10 pin 5) :     0.93v (@low Vol)    / 2.36v (@med Vol)    / 2.98v (Full vol) 
   Voltage bottom of R37 (C22)     :      0.8 V                    /  1.72v                     /   2.47v

Q7
I checked Q7 confirmed correct insertation.  Soldering looks good as far as I can see without any soldering whiskers. But it's hard to see since it's under the Volume pot. 

C22:
Ajparent1 is the second person mentioning installing C22 incorrectly. C22 doesn't have polarity. It is installed at the correct place. 

----

SO I guess we seem to have concurence that C22 may be bad and to proceed with taking it out and measuring IC10 voltage per Alan's post ??
(I'd rather remove c22 than IC10, so that is kind of a good news among the bad news) 

BTW, I want to thank everyone for helping me.   This has been educational.  




Jose Tent
 

Mutimeter:
    I'm using a 10030S Southwire digital multimeter.  Cheap, but not the absolute bottom of the barrel either.   

R37 Voltage REDUX:
I rechecked the voltage on R37 today again.   Well, the voltage on the top connected to IC10 Pin 5 is always higher by a bit through the swing of the volume pot. 
   Voltage top of R37 (IC10 pin 5) :     0.93v (@low Vol)    / 2.36v (@med Vol)    / 2.98v (Full vol) 
   Voltage bottom of R37 (C22)     :      0.8 V                    /  1.72v                     /   2.47v

Q7
I checked Q7 confirmed correct insertation.  Soldering looks good as far as I can see without any soldering whiskers. But it's hard to see since it's under the Volume pot. 

C22:
Ajparent1 is the second person mentioning installing C22 incorrectly. C22 doesn't have polarity. It is installed at the correct place. 

----

SO I guess we seem to have concurence that C22 may be bad and to proceed with taking it out and measuring IC10 voltage per Alan's post ??
(I'd rather remove c22 than IC10, so that is kind of a good news among the bad news) 

BTW, I want to thank everyone for helping me.   This has been educational.  




ajparent1/KB1GMX
 

A large votlage drop would take a terrible meter to produce that its something on
the board likely C22 backward or solder whisker maybe even a bad part.

Maybe Q7 inserted wrongly.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting


g4edg
 

Just wondering if the voltage drop across R37 is due to the quality of the meter being used for the measurement?

Also wondering if Q7 is OK and not short circuit? Could be shunting the audio to ground? Any voltage on the gate that would cause this?

Just saying, as these things have not been mentioned before.

Watching with interest!

73 Steve G4EDG


Alan G4ZFQ
 

Jose,

C22 is installed and confirmed that it is the correct capacitor. This
one doesn't have a polarity does it ?
No, as others have said the schematic shows an older version.

R37 bottom (connected to C22) 1.73v
top (Connected to IC10 Pin 5) : 2.32v
This shows current is flowing through R37. It should not.
It could be due to dirt or connection to somewhere else by a whisker of solder.
Or, a leaky C22. Look carefully with a glass, if the connection looks clean then remove C22. (Break it and remove each leg separately.) Then measure the IC10 voltages. They should be correct.
If so fit a new C22.

73 Alan G4ZFQ


Jose Tent
 

I see that the c22 and few capacitor values were modified somewhere in the Rev.  

The circuit diagram in the assembly manual has been updated to reflect the change.  The diagram on the "TROUBLESHOOTING" page still has the old values. 


Jose Tent
 

Looking through the assembly manual (P31)


and then the circuit diagram . 




One indicates    1uF   vs 10 uF.....   ???????    105 is 1uF.... so clearly the manual is correct.

They should update this....


Jose Tent
 

On Sat, May 30, 2020 at 11:48 PM, Alan G4ZFQ wrote:
Jose,

Before you do any pictures please check this.
Or, at least confirm you have checked.
Voltages here will tell if IC10 is faulty. Reiner has said the same.

73 Alan G4ZFQ
R37 bottom (connected to C22)   1.73v 
        top (Connected to IC10 Pin 5)   :   2.32v

C22 is installed and confirmed that it is the correct capacitor.  This one doesn't have a polarity does it ?  Not sure how to check if it leaky....(Googling) 


Alan G4ZFQ
 

Have you checked voltages each side of R37? Is C22 installed the correct way round? Is it leaky?
Jose,

Before you do any pictures please check this.
Or, at least confirm you have checked.
Voltages here will tell if IC10 is faulty. Reiner has said the same.

73 Alan G4ZFQ


Jose Tent
 

On Sat, May 30, 2020 at 07:13 AM, <ed.j.tink@...> wrote:

Obviously, you have found a problem. But, If you don't mind, can you send a close up picture of both sides without the LCD attached?

I fresh pair of eyes may help.
Happy to do it. and thanks for the offer. 

I'll post some thing tomorrow.  I'm too blurry eyed after working few hours today.  

Posting my soldering acumen for everyone to see feels a bit like posting my picture in the buff.... But I'll do it. 


ed.j.tink@...
 

Hi Jose,

Obviously, you have found a problem. But, If you don't mind, can you send a close up picture of both sides without the LCD attached?

I fresh pair of eyes may help.

Ed


dl8lrz
 

I only see 2 options:
- Current flows to the ground via C22, the voltage at PIN6 becomes too low compared to PIN5. Then PIN7, 3, 2.1 can be nearly 12v.
- IC10 is defective.
Read how to remove circuits. The board can be destroyed
I wish you success
73 Reiner


Alan G4ZFQ
 

Jose,

Measured voltage for IC10 are:   pin  1  ~ 8   : 1=11.7  /2= 11.7 / 3=11.7 /4=0 == 5=3.3 / 6=2.31 / 7=11.7 / 8=11.7   (Volts)
But, perhaps I should just replace the IC rather than
wondering if it's good or NG.
The voltages seem to indicate it is good. Pin 6 is much lower than pin 5 even though it is fed from pin 7 which is very high.
I've not been following too closely. Have you checked voltages each side of R37? Is C22 installed the correct way round? Is it leaky?

73 Alan G4ZFQ