Topics

QCX+ Button


William Bradley
 

Have just assembled the QCX+ for 30m band, it passed the smoke test, the LCD displays properly, was able to select the band, then I found that the menu button did not work.  I reflowed the solder joints on the button but that made no difference.

Any ideas please?  Thanks

Roger mi0wwb


Brian N7BKV
 

William--

I found continuity problems between the front PCB sockets and the JP3,4,5 on the main board.  Solution was to bend the last 3mm of the pins a bit up and twist each one about 15 degrees.  Never figured out which pin was the bad boy, but after a couple of tries the continuity problems were solved.  Until then the whole front panel LCD and Control array was really wonky. Actually blew the 2 Amp fuse in the supply power line to the radio.  Dunno fur sure what exactly it was.  But this procedure solved all the issues.

GL and 73
Brian N
N7BKV


On Sat, Oct 17, 2020 at 03:35 AM, William Bradley wrote:
Have just assembled the QCX+ for 30m band, it passed the smoke test, the LCD displays properly, was able to select the band, then I found that the menu button did not work.  I reflowed the solder joints on the button but that made no difference.

Any ideas please?  Thanks

Roger mi0wwb


William Bradley
 

Thanks Brian

I have come across the issue, wrong resistor values!!

Roger de mi0wwb


Shane Justice
 

Brian,

Thanks for your observation!
I am tracking down a similar issue-  My QCX powered up properly,  I set the band (40m),
Set the frequency for the tcxo, but when entering 8.7 menu Peak BP Filter, there is no 700Hz tone, and the scaling factor reads 00. Rotating C1 to peak the filter has no effect. I've rotated the audio volume control from min to max, with no change. 

Restarting the radio from power-up, I hear several clicks from the headset, so the final audio amplifier is at least powered up and connected to headphone jack.

I've traced through audio stage and find no modulation.

I then skipped to check the TCXO/ Si5351- JP2 Clocks are present at 0, 1,& 2. 7.02MHz (by my oscilloscope's frequency counter).

IC3 inputs show this signal is making it to the pins of the IC. Based on inputs to IC3, the outputs are appropriate on IC3- no TX output (Menu 8.7 active), RX output has 7.02 MHz output. 

Thinking the BPF peaking has signal injection through T1, I checked secondary (large coil) of T1, which appears to have no signal.

During this time, I notice a brief flicker of bargraph - I haven't been able to isolate the exact path that is intermittent yet. While exploring this intermittent affect, I accidently switched to 8.8, and saw bar graph oscillations- this indicates to me that the RF side of things is likely working. BUT while looking at whether the volume control affects the 8.8 display, I found it had no effect. I was expecting to see volume control effects on the bargragh/ multiplier data, from some forum discussions.

I SWITCHED, again, my focus to the volume control and connections on the control panel- the volume control left and center connections are continuous to the front panel  2x3 socket, checking the contacts with leads pushed into the connector.

I then checked continuity to the main circuit board with the front panel mated. I found continuity on only one of the two audio potentiometer pins. I am in the middle of desoldering and resoldering these connectors.

As the schematic is in color, and I have old eyes with difficulty seeing the grayish traces, I am not able to trace the signal path on the complete schematic, and I am attempting to do so with the magnified snippets of the schematic in the manual, but I find there are critical parts of the chain omitted from each fragment, so I'm having difficulty connecting the dots.

I tried printing the schematic out in black and white, but the light blue/gray colored text and traces come out with just as poor contrast as the color.

Suggestions on any and all of this are appreciated.

73,
Shane
KE7TR


On Oct 17, 2020 at 07:20, Brian N7BKV <cl@...> wrote:

William--

I found continuity problems between the front PCB sockets and the JP3,4,5 on the main board.  Solution was to bend the last 3mm of the pins a bit up and twist each one about 15 degrees.  Never figured out which pin was the bad boy, but after a couple of tries the continuity problems were solved.  Until then the whole front panel LCD and Control array was really wonky. Actually blew the 2 Amp fuse in the supply power line to the radio.  Dunno fur sure what exactly it was.  But this procedure solved all the issues.

GL and 73
Brian N
N7BKV

On Sat, Oct 17, 2020 at 03:35 AM, William Bradley wrote:
Have just assembled the QCX+ for 30m band, it passed the smoke test, the LCD displays properly, was able to select the band, then I found that the menu button did not work.  I reflowed the solder joints on the button but that made no difference.

Any ideas please?  Thanks

Roger mi0wwb


Shane Justice
 

Update!

I went over the main PCB with my phone camera on 8X power and found several questionable solder joints. I used flux flush and then reapplication of fresh solder and I now have BPF peaking roughly midway in the 7's. I am going to watch Hans' QCX+ tune up video again to understand which inductors to change, and go from there. Still no headset audio- I'll sort that out next.

Regards,
Shane


On Oct 17, 2020 at 14:47, Shane Justice via groups.io <justshane@...> wrote:

Brian,

Thanks for your observation!
I am tracking down a similar issue-  My QCX powered up properly,  I set the band (40m),
Set the frequency for the tcxo, but when entering 8.7 menu Peak BP Filter, there is no 700Hz tone, and the scaling factor reads 00. Rotating C1 to peak the filter has no effect. I've rotated the audio volume control from min to max, with no change. 

Restarting the radio from power-up, I hear several clicks from the headset, so the final audio amplifier is at least powered up and connected to headphone jack.

I've traced through audio stage and find no modulation.

I then skipped to check the TCXO/ Si5351- JP2 Clocks are present at 0, 1,& 2. 7.02MHz (by my oscilloscope's frequency counter).

IC3 inputs show this signal is making it to the pins of the IC. Based on inputs to IC3, the outputs are appropriate on IC3- no TX output (Menu 8.7 active), RX output has 7.02 MHz output. 

Thinking the BPF peaking has signal injection through T1, I checked secondary (large coil) of T1, which appears to have no signal.

During this time, I notice a brief flicker of bargraph - I haven't been able to isolate the exact path that is intermittent yet. While exploring this intermittent affect, I accidently switched to 8.8, and saw bar graph oscillations- this indicates to me that the RF side of things is likely working. BUT while looking at whether the volume control affects the 8.8 display, I found it had no effect. I was expecting to see volume control effects on the bargragh/ multiplier data, from some forum discussions.

I SWITCHED, again, my focus to the volume control and connections on the control panel- the volume control left and center connections are continuous to the front panel  2x3 socket, checking the contacts with leads pushed into the connector.

I then checked continuity to the main circuit board with the front panel mated. I found continuity on only one of the two audio potentiometer pins. I am in the middle of desoldering and resoldering these connectors.

As the schematic is in color, and I have old eyes with difficulty seeing the grayish traces, I am not able to trace the signal path on the complete schematic, and I am attempting to do so with the magnified snippets of the schematic in the manual, but I find there are critical parts of the chain omitted from each fragment, so I'm having difficulty connecting the dots.

I tried printing the schematic out in black and white, but the light blue/gray colored text and traces come out with just as poor contrast as the color.

Suggestions on any and all of this are appreciated.

73,
Shane
KE7TR


On Oct 17, 2020 at 07:20, Brian N7BKV <cl@...> wrote:

William--

I found continuity problems between the front PCB sockets and the JP3,4,5 on the main board.  Solution was to bend the last 3mm of the pins a bit up and twist each one about 15 degrees.  Never figured out which pin was the bad boy, but after a couple of tries the continuity problems were solved.  Until then the whole front panel LCD and Control array was really wonky. Actually blew the 2 Amp fuse in the supply power line to the radio.  Dunno fur sure what exactly it was.  But this procedure solved all the issues.

GL and 73
Brian N
N7BKV

On Sat, Oct 17, 2020 at 03:35 AM, William Bradley wrote:
Have just assembled the QCX+ for 30m band, it passed the smoke test, the LCD displays properly, was able to select the band, then I found that the menu button did not work.  I reflowed the solder joints on the button but that made no difference.

Any ideas please?  Thanks

Roger mi0wwb


Brian N7BKV
 

Volume control should have an effect.  Keep cranking it up and adjusting until you find the sweet minimum bar in either 08 or 09.  Sensitivity goes up each time the bar flips up a number.  Me thinks you still have a continuity issue between the front PCB (volume control circuit) and the main board.  Try out what I suggested regarding bending and twisting the JP3,4 and 5 pins.  The fact you got a flicker is indicating a continuity issue there.  GL on it.  If you are lucky it will be that simple

Brian N
N7BKV


On Sat, Oct 17, 2020 at 02:47 PM, Shane Justice wrote:
BUT while looking at whether the volume control affects the 8.8 display, I found it had no effect. I was expecting to see volume control effects on the bargragh/ multiplier data, from some forum discussions.


Shane Justice
 

Hi Brian,
Thanks for your response. I have to figure out why I have no headphone sound. I need to trace from the start of the audio chain to see why there's no audio. The BPF is sitting about midway in the 8 range, but it looks like C1 is closer to the minimum side, so I may need to remove a turn from T1 large secondary.

I'm going to inspect the main board again, and look for questionable solder joints.

Best Regards,
Shane


On Oct 17, 2020 at 19:51, Brian N7BKV <cl@...> wrote:

Volume control should have an effect.  Keep cranking it up and adjusting until you find the sweet minimum bar in either 08 or 09.  Sensitivity goes up each time the bar flips up a number.  Me thinks you still have a continuity issue between the front PCB (volume control circuit) and the main board.  Try out what I suggested regarding bending and twisting the JP3,4 and 5 pins.  The fact you got a flicker is indicating a continuity issue there.  GL on it.  If you are lucky it will be that simple

Brian N
N7BKV

On Sat, Oct 17, 2020 at 02:47 PM, Shane Justice wrote:
BUT while looking at whether the volume control affects the 8.8 display, I found it had no effect. I was expecting to see volume control effects on the bargragh/ multiplier data, from some forum discussions.


Ian VA7ITM
 

Hi Shane,

You should probably start a new thread for this instead of under QCX+ button!

I currently have the same problem as you... no audio out.

Just to confirm, when calibrating BPF (which is independent of the volume control) you have no audio in your earphones? I don't... even though the manual warns there will be a loud tone. I can still successfully calibrate to "8".

But the next test is to check the I-Q Balance (Menu 8-8). This does require the volume and it should be adjust so the display read 5-10. In my case it is 0, regardless of the volume level.

Currently I have traced from the volume pot and for each of the 3 legs on the pot I have good connectivity to the first components on the main PCB... i.e. ground, C21 and C22.

Someone else previously reported a similar problem and traced it to a bad C21. I replaced both C21 and C22 but still no audio (and I measured the originals after I removed them and they were good).

I have a small, cheap oscilloscope and will now try using that to follow the path.

73 Ian VA7ITM


Shane Justice
 

Hi Ian,
Thanks for suggesting a new topic thread. I'll give that a try about 10-12 hours from now, as I'm winding down to sleep. Glad you have continuity at the front panel to main board interface. I'm thinking of jumpering past the 2x3 plug/socket to see what happens.

I checked voltages on all the pins from the clk1 and clk2 outputs all the way through what I believe is a digital mux, through the I and Q paths, all the way through to the head phone jack.

You are correct- I have no audio in the head phones, but I do hear an audible click in the he'd phones when powering up the QCX+, and again when I select the bpf peak. The BPF peaks about 1/2 bars on level 8, but the C1 position is at the start of the range of C1, indicating I need to modify the turns of S3 (the largest number of turns on T1). I may have the designation wrong- I'm tired and not looking at the manual. Trouble is, the other peak is nearly as large, and occurs at the C1 maximum! 

I an Q are supposed to be out of phase, but there is no varying on the I and Q channels, so there is no audio tone. Also, even if there was, the volume control is effectively out of circuit on my kit, so even if there was I and Q data, I don't believe I would get the tone.

I understand you believe that there should be a tone, even with the potentiometer turned all the way down. I don't know, at the moment, how to judge where I should be concentrating my effort, but my gut feeling is I have to get the volume control working, as if not, doing anything beyond 8.7 isn't going to be fruitful.

Do you get clicks on your speaker or headphones when you power up your kit? How about when you select 8.7 bog peaking?

Thanks for your reply!

Best Regards,
Shane


On Oct 18, 2020 at 02:31, Ian VA7ITM <ian.mcalpine@...> wrote:

Hi Shane,

You should probably start a new thread for this instead of under QCX+ button!

I currently have the same problem as you... no audio out.

Just to confirm, when calibrating BPF (which is independent of the volume control) you have no audio in your earphones? I don't... even though the manual warns there will be a loud tone. I can still successfully calibrate to "8".

But the next test is to check the I-Q Balance (Menu 8-8). This does require the volume and it should be adjust so the display read 5-10. In my case it is 0, regardless of the volume level.

Currently I have traced from the volume pot and for each of the 3 legs on the pot I have good connectivity to the first components on the main PCB... i.e. ground, C21 and C22.

Someone else previously reported a similar problem and traced it to a bad C21. I replaced both C21 and C22 but still no audio (and I measured the originals after I removed them and they were good).

I have a small, cheap oscilloscope and will now try using that to follow the path.

73 Ian VA7ITM


Ian VA7ITM
 

Hi Shane,

I get I click/clunk through the earphones on power up and also when I key. But with the Peak BPF test I hear a very very very faint tone and with the I-Q balance test the volume control does nothing and the display shows "00".

So I think we are both in the same boat. Right now I am reviewing the circuit description in the manual and looking at the trouble-shooting guide to understand where the tone for the BPF test comes from because that is independent of the volume control and doesn't work.

Aside: My QCX+ actually worked for a couple of days after I first built it. I'm not sure if this is a coincidence but I wanted to see the minimum voltage to get the QCX+ to work so lowered the voltage on my PSU until the QCX+ powered off. When I powered on the next day it wasn't working!

Obviously I  will let you know if I find anything.

73 Ian VA7ITM


Shane Justice
 

Hi Ian,

You might want to factory reset your QCX+ and see if that corrects your issue. The brownout condition could have caused some sort of corruption of settings/configuration.

I hope yours comes back to life!

Shane


On Oct 18, 2020 at 23:37, Ian VA7ITM <ian.mcalpine@...> wrote:

Hi Shane,

I get I click/clunk through the earphones on power up and also when I key. But with the Peak BPF test I hear a very very very faint tone and with the I-Q balance test the volume control does nothing and the display shows "00".

So I think we are both in the same boat. Right now I am reviewing the circuit description in the manual and looking at the trouble-shooting guide to understand where the tone for the BPF test comes from because that is independent of the volume control and doesn't work.

Aside: My QCX+ actually worked for a couple of days after I first built it. I'm not sure if this is a coincidence but I wanted to see the minimum voltage to get the QCX+ to work so lowered the voltage on my PSU until the QCX+ powered off. When I powered on the next day it wasn't working!

Obviously I  will let you know if I find anything.

73 Ian VA7ITM