Good day to you guys! I normaly post or read about my DIY Microphone Projects, but I have a new... DIY repair to do haha!
I have a Yamaha AG06 Mixer and USB interface. Did communicate twice with Yamaha technical support, and the answer was : "Due to the low cost of the AG-06 they are not economical to repair."
Here is the thing.
When using a dynamic mic, the input 1 is about 10db lower in gain compared to what it used to be, and compared to the input 2. (and obviously I'm not using the PAD button...). Cranking the gain brings the noise floor too high.
When using condenser mics... it gets interesting :
Thanks for helping me,
David
I have a Yamaha AG06 Mixer and USB interface. Did communicate twice with Yamaha technical support, and the answer was : "Due to the low cost of the AG-06 they are not economical to repair."
Here is the thing.
When using a dynamic mic, the input 1 is about 10db lower in gain compared to what it used to be, and compared to the input 2. (and obviously I'm not using the PAD button...). Cranking the gain brings the noise floor too high.
When using condenser mics... it gets interesting :
- Samson CO2 : Works well with 48v, aside from being most likely 10db lower gain
- Sennheiser M66/K6 without battery : Nothing with 48v... hear some static at first then it fades away
- Studio Project B1 : Nothing with 48v...
- Deity V-Mic D3 without battery + Rode VXLR+ : Nothing with 48v...
- Reset the Mixer
- Update and reset the AG DSP Controler
- Tested various cables
- Tested other mixers
- Cleaned the connectors
- Cleaned the circuit board
- Tested voltage output (48v on both pin 1 and 2)
- Forced pins inward/outward
Thanks for helping me,
David
Hmmm. I don't have any schematics or anything, but signal reduction and inability to power from phantom (despite observing it, presumably with a DMM) would first lead me to suspect a resistance value may have shifted (burned, broken, etc). Usually there's a couple of resistors from the main +48V supply to each leg of the XLR; see Jensen Transformers Preamp Input Circuitry for an example. If any of those resistors sees a significant increase in value, for example, you would see a voltage drop across it that would vary depending on the microphone's current draw - some mikes might not draw enough to be bothered, others might draw too much to function. If one leg has +48V and the other leg has +24V... I can easily imagine the mike being unhappy.
As Enzo points out, though, this is all speculation without a schematic. My days as an audio repair tech are WELL behind me.
As Enzo points out, though, this is all speculation without a schematic. My days as an audio repair tech are WELL behind me.
Thanks Enzo. Just to make it clear. I'm somehow knowledgeable in this area so yes, the obvious tests have been done. I have other mixers/recorders and all the tested microphones are fine. And yes, the PAD button does reduce the level as expected even on the input 1.
The schematic is available in the Data Sheet here attached (or https://usa.yamaha.com/products/music_production/interfaces/ag_series/downloads.html)
The schematic is available in the Data Sheet here attached (or https://usa.yamaha.com/products/music_production/interfaces/ag_series/downloads.html)
Thanks rco3. Any way I can test that? I have a lot of electronics available (breadcrumbs, boards, resistors, capacitors, etc.)...
That is not a schematic, that is an overview.
I just looked the model up on my dealer support portal, No schematic. Just a service bulletin about canging brands of mini-jacks.
I just looked the model up on my dealer support portal, No schematic. Just a service bulletin about canging brands of mini-jacks.
Or block diagram. Pesky small details omitted so you see the big picture at user-level.
A different but similar Yamaha schematic. Note every last resistor and capacitor and interconnections.
10dB only on "some" mikes.... balanced mike is two signal wires. If one is broken (bad PCB, dirty switch-jack), the fault may be small, large, or something between.
Thanks a lot everyone. So what tests would you guys suggest to help identify where the issue is? Other than "get a new mixer"...
Your saying input 1 is low .... the signal goes directly through the headset mic jack socket ... if you've not used this headset socket in ages the "normalled" (closed) connections in it can get oxidized and make for bad continuity ... it happens all the time with guitar amp FX loop sockets etc.
Try spraying some contact cleaner or alchohol into the headset socket and inserting a suitable jack plug a good few times and see if there is any difference ... got to try the simple stuff first ... 🙂
Try spraying some contact cleaner or alchohol into the headset socket and inserting a suitable jack plug a good few times and see if there is any difference ... got to try the simple stuff first ... 🙂
In fact, the issue is right from the input. The gain nob needs to be turned more to compensate (compared to the original state and to the second input). So yes, I can then monitor the difference and when testing the recording of both channels 1 and 2 over the usb interface on my PC, we can see the 10db difference. All indicators also react to this difference (signal and peak).
I have multimeters, and various tools for electronic projects (like breadcrumbs, boards, resistors, capacitors, etc). I build my own microphones and other small electronic projects.
I have multimeters, and various tools for electronic projects (like breadcrumbs, boards, resistors, capacitors, etc). I build my own microphones and other small electronic projects.
You shouldn’t have 48 volts on both pins 1 & 2. Try measuring from 1-2, 1-3 & 2-3. Next turn off the phantom power and inject signal into all three combinations.
If the channel peak shows the difference then it is before that ... as simon says check your pins then inject and trace signal, should be quick to find ... 🙂
Just read your reply again and finally realized what you meant by the headset mic jack socket! I'll test this out since yes, I also use this one from time to time.
I only use pro headphones on the monitor 1/4 jack.
I normally have 1 mic connected to the input 1, my headphones and the USB cable going from my PC to the Mixer. I've also try running the mixer directly using a micro-usb cable. I chose this mixer because of the live comp option on input 1. Switching to input 2, I loose both the comp and the 48v.
I used the following technique (that I found on Sure support site) to test so far :
- Measure from XLR pin 2 to XLR pin 1. Note the voltage (48)
- Measure from XLR pin 3 to XLR pin 1. Note the voltage. (48)
- The DC voltages measured was exactly the same - to the tenth of a volt.
- Measure from pin 2 to pin 3. The DC voltage was zero.
- Make these measurements at the microphone location, but with the microphone disconnected.
- Set the Volt/Ohm/Amp meter to read from 0 to 100mA DC.
- Measure current by connecting the positive meter lead to XLR pin 2 and the negative lead to XLR pin 1. The reading should be approximately 7mA.
- Repeat the previous step using XLR pin 3 and XLR pin 1. The reading should be approximately 7mA.
Same question... how do I inject and trace signal?
Thanks a lot all of you, it is immensely appreciated!
Interesting problem and some good trouble shooting going on in the thread. 
There seems to be two problems, likely related. Channel 1 low gain, and Channel 1 phantom power problems.
Not sure from the thread, but levels and phantom are acting normally on channel 2?
If so, can you measure the phantom voltage with a mic connected? Is it the same on channels 1 and 2? (Thinking current draw, as noted by others)
The two problems would make me think that there is either a semi-short on channel 1, or a bad connection. Either or both of those could cause a level drop and limit phantom current.
There seems to be two problems, likely related. Channel 1 low gain, and Channel 1 phantom power problems.
Not sure from the thread, but levels and phantom are acting normally on channel 2?
If so, can you measure the phantom voltage with a mic connected? Is it the same on channels 1 and 2? (Thinking current draw, as noted by others)
The two problems would make me think that there is either a semi-short on channel 1, or a bad connection. Either or both of those could cause a level drop and limit phantom current.
Channel 2 does not offer phantom power.
So still wondering how test the "current draw" and/or "inject and trace signal"
So still wondering how test the "current draw" and/or "inject and trace signal"
Ah, no phantom on 2, that makes it more difficult. We use this range of mixers a lot for in-room A/V in hotels, Yamaha has sold a lot of them. They don't get fixed when they malfunction.
If you open up one end or the other of your XLR cable you can measure the phantom voltage with a mic plugged in. You've already seen 48V at no load, but if you measure a big drop with a powered mic, then we can assume that there is a current restriction. That may, or may not, be related to your gain problem.
If you open up one end or the other of your XLR cable you can measure the phantom voltage with a mic plugged in. You've already seen 48V at no load, but if you measure a big drop with a powered mic, then we can assume that there is a current restriction. That may, or may not, be related to your gain problem.