No output, Reason to worry #qcx #40m


KI7MWA
 

No output power on my QCX40.  LPF is continuous from end to end.

On the Troubleshooting page, Hans says, in reference to IC3:

"Again the 0V and 5V in this chart, should measure pretty close to 0V and 5V. 4.8V, 4.9... fine... 0.1V, fine... but if you see 1V somewhere, then that is a reason to worry. "

I get 1 volt (+/- 0.02) on pin 9, whether in transmit or receive.  Microcontroller pin 17 (SigOut) shows continuity with pin 9 of IC3.  My microcontroller is rev T1.00g, and it is installed correctly, with pin 1 at the top-right corner.

Do I need to continue looking for a wiring fault, or just replace the microcontroller?


James Daldry W4JED
 

Hi, Entilleser

The line in question has 3 components attached to it, and 2 different functions. Function 1 is the MOSI signal used in programming the micro, and function 2 is to turn the alignment signal for the receiver on and off. It has no effect on the transmitter output.

Since there are the micro, IC3, and the programming connector connected together, any one of the 3, and any part of the connecting foil, can cause the problem. The simplest test to start with is to remove one of the components, by pulling the micro out of its socket. Then check the resistance from pin 17 of the micro socket to ground. Since all that's left on the line are the programming socket and a cmos input (essentially a capacitor) you should read infinite ohms with the meter probes in either direction. Infinite reading, micro problem. Any other reading, keep looking for stray wire clippings, solder whiskers, etc.

40+ years in consumer electronic service tell me that if you have a bad micro, something blew it. So micro repairs are always micro plus whatever blew it.

73

Jim W4JED

On 1/30/20 4:31 PM, entilleser via Groups.Io wrote:
No output power on my QCX40.  LPF is continuous from end to end.

On the Troubleshooting page, Hans says, in reference to IC3:

"Again the 0V and 5V in this chart, should measure pretty close to 0V and 5V. 4.8V, 4.9... fine... 0.1V, fine... but if you see 1V somewhere, then that is a reason to worry. "

I get 1 volt (+/- 0.02) on pin 9, whether in transmit or receive.  Microcontroller pin 17 (SigOut) shows continuity with pin 9 of IC3.  My microcontroller is rev T1.00g, and it is installed correctly, with pin 1 at the top-right corner.

Do I need to continue looking for a wiring fault, or just replace the microcontroller?


ae1ct1998 <AE1CT1998@...>
 

I've built a dozen qcx radios and never had any problems with them  not working. 


On Fri, Jan 31, 2020, 09:01 James Daldry W4JED <jim@...> wrote:

Hi, Entilleser

The line in question has 3 components attached to it, and 2 different functions. Function 1 is the MOSI signal used in programming the micro, and function 2 is to turn the alignment signal for the receiver on and off. It has no effect on the transmitter output.

Since there are the micro, IC3, and the programming connector connected together, any one of the 3, and any part of the connecting foil, can cause the problem. The simplest test to start with is to remove one of the components, by pulling the micro out of its socket. Then check the resistance from pin 17 of the micro socket to ground. Since all that's left on the line are the programming socket and a cmos input (essentially a capacitor) you should read infinite ohms with the meter probes in either direction. Infinite reading, micro problem. Any other reading, keep looking for stray wire clippings, solder whiskers, etc.

40+ years in consumer electronic service tell me that if you have a bad micro, something blew it. So micro repairs are always micro plus whatever blew it.

73

Jim W4JED

On 1/30/20 4:31 PM, entilleser via Groups.Io wrote:
No output power on my QCX40.  LPF is continuous from end to end.

On the Troubleshooting page, Hans says, in reference to IC3:

"Again the 0V and 5V in this chart, should measure pretty close to 0V and 5V. 4.8V, 4.9... fine... 0.1V, fine... but if you see 1V somewhere, then that is a reason to worry. "

I get 1 volt (+/- 0.02) on pin 9, whether in transmit or receive.  Microcontroller pin 17 (SigOut) shows continuity with pin 9 of IC3.  My microcontroller is rev T1.00g, and it is installed correctly, with pin 1 at the top-right corner.

Do I need to continue looking for a wiring fault, or just replace the microcontroller?


George Korper
 

It can be helpful if you send us a high res pix top and bottom, so we can help you search for the obvious. BTW this group is very supportive but it may take a couple of days. My assembly skills and the density of small parts is intimidating and every kit is a challenge. Others find it a breeze. I guess that entitlement is sometimes shared but really not helpful.


On Fri, Jan 31, 2020, 8:17 AM ae1ct1998 <AE1CT1998@...> wrote:
I've built a dozen qcx radios and never had any problems with them  not working. 

On Fri, Jan 31, 2020, 09:01 James Daldry W4JED <jim@...> wrote:

Hi, Entilleser

The line in question has 3 components attached to it, and 2 different functions. Function 1 is the MOSI signal used in programming the micro, and function 2 is to turn the alignment signal for the receiver on and off. It has no effect on the transmitter output.

Since there are the micro, IC3, and the programming connector connected together, any one of the 3, and any part of the connecting foil, can cause the problem. The simplest test to start with is to remove one of the components, by pulling the micro out of its socket. Then check the resistance from pin 17 of the micro socket to ground. Since all that's left on the line are the programming socket and a cmos input (essentially a capacitor) you should read infinite ohms with the meter probes in either direction. Infinite reading, micro problem. Any other reading, keep looking for stray wire clippings, solder whiskers, etc.

40+ years in consumer electronic service tell me that if you have a bad micro, something blew it. So micro repairs are always micro plus whatever blew it.

73

Jim W4JED

On 1/30/20 4:31 PM, entilleser via Groups.Io wrote:
No output power on my QCX40.  LPF is continuous from end to end.

On the Troubleshooting page, Hans says, in reference to IC3:

"Again the 0V and 5V in this chart, should measure pretty close to 0V and 5V. 4.8V, 4.9... fine... 0.1V, fine... but if you see 1V somewhere, then that is a reason to worry. "

I get 1 volt (+/- 0.02) on pin 9, whether in transmit or receive.  Microcontroller pin 17 (SigOut) shows continuity with pin 9 of IC3.  My microcontroller is rev T1.00g, and it is installed correctly, with pin 1 at the top-right corner.

Do I need to continue looking for a wiring fault, or just replace the microcontroller?


KI7MWA
 

Hi James, thanks for responding.  In answer to your suggestion, I pulled the microcontroller and checked resistance between socket 17 and the ground pin at the GPS antenna connection (lower-right corner, 3rd pin up).  My DVM read 9.6 Meg ohm.  Not infinite.  Big enough?


KI7MWA
 

George - I'm working on it...


KI7MWA
 

Just to avoid leading y'all astray, I should say that this was my first project at this level of complexity.  I managed to mount a couple of components wrongly, which I had to pull and re-mount in their correct places.  It is not impossible that, in the process, I did some damage to a trace, though I have been unable to discover anything in repeated examinations.


George Korper
 

Thanks. Take a close look for solder bridges on top and bottom of board. It's tough if you don't have spare parts,  that 
has been a problem for me in Mexico so I hope it isn't a component. Solder pads are very close together and on a cursory scan I eventually spotted one pad that was really two I had bridged.
I recently soldered a component and the solder went down the leg and bridged the board on the component side!

It ain't easy but you will see something
🤓
As for skill at this, my company sent me to China to a factory where there are woman who can assemble 12 radios probably in a day ( hi hi). And they are cute and cheerful! I don't recall them boasting. 

On Fri, Jan 31, 2020, 9:12 PM KI7MWA via Groups.Io <entilleser=yahoo.com@groups.io> wrote:
George - I'm working on it...


JohnL
 

I had something like what you described and couldn’t find the root cause. I ended up performing a factory reset and the transmit output just worked after that.  Worth a shot.  I too was running 1.00g firmware. 

Johnl


George Korper
 

Likewise. 


On Fri, Jan 31, 2020 at 11:11 PM JohnL <John.lengeling@...> wrote:
I had something like what you described and couldn’t find the root cause. I ended up performing a factory reset and the transmit output just worked after that.  Worth a shot.  I too was running 1.00g firmware. 

Johnl


James Daldry W4JED
 

Hi, KI7WMA

Yes, 9.6 megs should be big enough. Next step is to apply power with the micro and display removed and check the voltage on socket pin 17. It should be zero. You may have to wait with the meter probe connected for the gate capacitance to discharge, but it should reach zero within a second or two. If it doesn't you have a punctured gate cap on IC3. If it does go to zero, or starts at zero and stays there, we have that unicorn, a bad micro.

Jim W4JED

On 1/31/20 10:12 PM, KI7MWA via Groups.Io wrote:
Hi James, thanks for responding.  In answer to your suggestion, I pulled the microcontroller and checked resistance between socket 17 and the ground pin at the GPS antenna connection (lower-right corner, 3rd pin up).  My DVM read 9.6 Meg ohm.  Not infinite.  Big enough?


KI7MWA
 

For James: with microcontroller & LCD removed, voltage on microcontroller socket pin 17 steady at 1.09V for over a minute.  One punctured gate cap!

Some additional information (now that I've got a better handle on the troubleshooting guide): Voltages on IC3 pins while in transmit (nominal values in parens):

1: (5V square wave, ~2.5V RMS) +4.95VDC
2: (same as 1)
3: (5V square wave) 0 (zero) VDC
4: (3.3V square wave, ~ 1.65V RMS) ) 0VDC
5: (+5VDC) +4.95VDC
6: (same as 1) +4.95VDC
7: (0) 0VDC
8: (+5 VDC) 4.95VDC
9: (0) 1.3VDC
10: (same as 4) 0VDC
11: (+5VDC) 4.95VDC
12: (0) 0VDC
13: (0) 0VDC
14: (+5VDC) +4.95VDC

So, maybe more than 1 punctured gate cap?


Alan G4ZFQ
 

So, maybe more than 1 punctured gate cap?
As Jim has said, what caused it to go?
Are the BS170s all good? One thing that destroys IC3 is a drain/gate short.

73 Alan G4ZFQ


James Daldry W4JED
 

Hi. KI7MWA

Pin 3 with zero volts doesn't (don't?) look good. Check the resistance from pin 3 to ground. If it looks something like 0 ohms (should be infinite) check the resistance from the drains of Q's 1,2,and 3 to ground. Methinks you have blown finals, that in the process of killing Q6, also put 12 volts on pin 3 if IC3, toasting both IC3 and Q6. My remote guess is Q1, 2, 3, 6, and IC3 hosed. Sorry.

Jim W4JED

On 2/1/20 11:39 AM, KI7MWA via Groups.Io wrote:
For James: with microcontroller & LCD removed, voltage on microcontroller socket pin 17 steady at 1.09V for over a minute.  One punctured gate cap!

Some additional information (now that I've got a better handle on the troubleshooting guide): Voltages on IC3 pins while in transmit (nominal values in parens):

1: (5V square wave, ~2.5V RMS) +4.95VDC
2: (same as 1)
3: (5V square wave) 0 (zero) VDC
4: (3.3V square wave, ~ 1.65V RMS) ) 0VDC
5: (+5VDC) +4.95VDC
6: (same as 1) +4.95VDC
7: (0) 0VDC
8: (+5 VDC) 4.95VDC
9: (0) 1.3VDC
10: (same as 4) 0VDC
11: (+5VDC) 4.95VDC
12: (0) 0VDC
13: (0) 0VDC
14: (+5VDC) +4.95VDC

So, maybe more than 1 punctured gate cap?


ae1ct1998 <AE1CT1998@...>
 

When build the QCX radios I always use ic sockets that way if an ic goes bad it's alot easier to change rather than ruining the board trying to unfolded the pins.


On Sat, Feb 1, 2020, 16:06 James Daldry W4JED <jim@...> wrote:

Hi. KI7MWA

Pin 3 with zero volts doesn't (don't?) look good. Check the resistance from pin 3 to ground. If it looks something like 0 ohms (should be infinite) check the resistance from the drains of Q's 1,2,and 3 to ground. Methinks you have blown finals, that in the process of killing Q6, also put 12 volts on pin 3 if IC3, toasting both IC3 and Q6. My remote guess is Q1, 2, 3, 6, and IC3 hosed. Sorry.

Jim W4JED

On 2/1/20 11:39 AM, KI7MWA via Groups.Io wrote:
For James: with microcontroller & LCD removed, voltage on microcontroller socket pin 17 steady at 1.09V for over a minute.  One punctured gate cap!

Some additional information (now that I've got a better handle on the troubleshooting guide): Voltages on IC3 pins while in transmit (nominal values in parens):

1: (5V square wave, ~2.5V RMS) +4.95VDC
2: (same as 1)
3: (5V square wave) 0 (zero) VDC
4: (3.3V square wave, ~ 1.65V RMS) ) 0VDC
5: (+5VDC) +4.95VDC
6: (same as 1) +4.95VDC
7: (0) 0VDC
8: (+5 VDC) 4.95VDC
9: (0) 1.3VDC
10: (same as 4) 0VDC
11: (+5VDC) 4.95VDC
12: (0) 0VDC
13: (0) 0VDC
14: (+5VDC) +4.95VDC

So, maybe more than 1 punctured gate cap?


geoff M0ORE
 

What do you mean by unfolding the pins. I hope you don't mean that you are bending the IC pins before soldering. You do not need to bend any pins or wires before soldering to the PCB. Is this why so many builders are damaging the PCB when trying to remove a mis-placed component.

On 01/02/2020 21:49, ae1ct1998 wrote:
ruining the board trying to unfolded the pins.


KI7MWA
 

Heya, James!  Pin 3 to ground is 7 Meg ohm.  Q1, Q2, Q3 all show 5.8 Meg ohm drain (pin 1) to ground.


James Daldry W4JED
 

Sounds like we're down to a sick IC3.

Jim W4JED

On 2/1/20 7:31 PM, KI7MWA via Groups.Io wrote:
Heya, James!  Pin 3 to ground is 7 Meg ohm.  Q1, Q2, Q3 all show 5.8 Meg ohm drain (pin 1) to ground.


Alan G4ZFQ
 

Pin 3 to ground is 7 Meg ohm.  Q1, Q2, Q3 all show 5.8
Meg ohm drain (pin 1) to ground.
The short, if there was one could have been temporary as a BS170 broke down further.
I'd suggest checking Q6 and the BS170s properly.
I hesitate to suggest you check TX voltages in it's present state. But if you are not going to check/replace those parts testing will do no more harm than testing after IC3 replacement.

73 Alan G4ZFQ


James Daldry W4JED
 

Good idea, Alan

It won't hurt anything to make sure there's 12 volts where 12 volts belongs and zero volts where zero volts belongs in the output area before replacing IC3. Usually when transistors become wireistors they stay that way, but sometimes they become smokeisters or bangistors and open back up.

73

Jim W4JED

On 2/2/20 10:02 AM, Alan G4ZFQ wrote:
Pin 3 to ground is 7 Meg ohm.  Q1, Q2, Q3 all show 5.8
Meg ohm drain (pin 1) to ground.
The short, if there was one could have been temporary as a BS170 broke down further.
I'd suggest checking Q6 and the BS170s properly.
I hesitate to suggest you check TX voltages in it's present state. But if you are not going to check/replace those parts testing will do no more harm than testing after IC3 replacement.

73 Alan G4ZFQ