Hello, I am qu16 user bin. I have a problem with q16 recently. The first symptom is that when you turn it on, the pan sometimes goes back and forth from side to side and doesn’t boot. At that time, if you turn it back on once or twice, it boots normally. The second one is a bit serious. During use, channels 1 to 16 suddenly make strong noise. It becomes normal when you turn it off and turn it back on, but it’s a bit like that again. I did it at the performance site, but it doesn’t happen when I test it in the office. What is the problem? The grounding of the power was also normal. The only thing that is a little suspicious is that the airbounce was connected to the same power source together, but I do have some doubts because I use the motor. I did the grounding properly, and I also used the Sergio multi-tab for the console power, is it related to the noise phenomenon? Or is it a breakdown of q16?
It is not possible to diagnose your issue remotely, so it’d be best to contact your local distributor and have your Qu fully checked over and serviced if required.
You can see the full list of our distribution partners here - https://www.allen-heath.com/community/distributors/
Thanks,
Keith.
Maybe try a firmware reload…and then test it many times before taking it to a show.
Thank you very much for your response. I checked to send q16 to Samasound, a distributor in Korea, but they said they didn’t have any abnormal symptoms. So they can’t fix it. It’s a relief that there’s no problem, but I think it’ll still be unstable to use. I’ll try to reinstall the firmware when I get q16 back. What are some common cases where these symptoms can occur?
And write down some additional symptoms that may be related.
First, the led in the middle of the st2-channel channel meter is not displayed, but the distributor says there is no hardware problem. This symptom has been quite old. Second, I don’t know if this is an error, but for example, if you call in scene 50 and turn it off, scene 50 is normally called, but when you press the scene button, it shows scene 0, so I always had to scroll through 50 times. It was a little slow. I was wondering if this was a failure or if it was supposed to be like this
Observed problem:
The desk seems to “freeze” and make a noise in all output channels and auxiliaries.
The volume of the noise can not be changed or muted from the desk.
Nothing else, but noise will come through when this starts.
If the desk is switched for a significant time period eg. 30 minutes, it will work fine briefly.
How & when the problem happens:
a few minutes after switching on the mixer.
Once this starts, it doesn’t make a difference if you try to restart the desk or do a “hard reset”.
Trouble shooting done so far:
Section A
- Muting all input channels
Observation: Noise. Volume of noise not affected.
- Muting the sound desk
Observation: Noise. Volume of noise not affected.
- pushing down all faders to “zero”
Observation: Noise. Volume of noise not affected.
- pushing down master volume
Observation: Noise. Volume of noise not affected.
- Turning down the gain of the individual input channels.
Observation: Noise. Volume of noise not affected.
Section B
- disconnecting everything other than a single output lead to a single speaker.
Observation: The noise persists even if there is nothing else connected to the mixer.
- Running nothing but a single output cable to a speaker on output port: Main L
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Main R
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 1
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 2
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 3
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 4
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 5
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 6
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 7
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 8
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 9
Observation: Noise
- Running nothing but a single output cable to a speaker on output port: Mix Output 10
Observation: Noise
Section C
- changed the speaker, and repeated the above
Observation: Noise
- turning down the output volume on the speaker
Observation: Volume of noise changed. Able to turn down the volume to “zero”.
- Switched off the mixer, and switched it on again
Observation: Noise. Sometimes the screen did not light up.
- connected the mixer to a different power source
Observation: Noise
- tried to do a “hard reset”
Observation: Noise
Our conclusion:
The problem is most likely in the mixer
The problem takes time to surface. Currently it takes about 30 minutes for it to happen. Months ago it would take about 2 hours or so to happen.
Also in your case, it will be advisable to contact your responsible distributor:
Hello!
I have the same problem with the qu-16, slowly a noise appears as if the GND wire is missing at the signal input, until finally the console freezes and does not start. I replaced the CPU board (04-362 PCB ASSY QU-16 CPU) it did not solve. I noticed that the problem appears with the heating of the DSP out microchip ( pcb 004-1342). I also simulated the defect, if I heated it to over 60°C I could block it immediately. I replaced the DSP chip, it did not solve. I replaced the DSP pcb board, the problem reappeared after 2 weeks of use
Hello again, I’m back. Last night I disassembled the mixer again, checked the SMPS source, replaced U4 TL431, removed the C4 capacitor, put 3 light bulbs as loads (Be careful, do not power it without a load! the capacitors on the +/-15 V outputs will explode, it only has feedback on the 7.5V output). I adjusted the source to 7.5V, I took the PCB board with the XLR/jack connectors, I redid all the solder joints of the connectors that make the connection between the boards, I reassembled it, it started from the first time, I heated the board with DSP up to about 82 °C (that’s what it says on the display) from last night until now it’s been running continuously, that humming hasn’t reappeared, it hasn’t stuck after restarts, it seems to be behaving normally, I’ll be back with news!
That’s awesome ! 
Giga
H
ello guys! I’m back with news regarding the problem with my QU-16, I found the problem and the solution. So the problem was as follows: after a while, especially when it was heating up, a buzz appeared on all the outputs and you couldn’t turn it back on until after a while. on the PCB board with DSP for outputs there is a network voltage monitoring (in the service diagram the power supply diagram appears, and it is noted PSU_PF1L, normally it should stay stable at 3V, when D1 and Q1 heat up, it seems that Q1 acts a little earlier, thinking it is a kind of “on/off” and hence that specific buzz. I replaced C1, D1, Q1, R1, but I only moved the defect to a higher temperature by over 15..20C. The solution was to insert the D1 diode in series with another diode so that the optocoupler cannot be activate Q1. I am very curious what the purpose of “PSU_PF1L” is,
maybe a qu-16 developer can explain it to usTHANK YOU! I managed to make some videos simulating the defect) if you want I can show
That’s Impressive 
Giga