I have a strange behavior with a pioneer DJM600 mixer.
Channels 1-2-4 operate logarithmically. Channel 3 behaves linearly.
Changed all the faders (as I also have another mixer for a donor, logarithmic not linear), trim, bass, mid, treble, fresh solder everywhere.
The strange thing now, the signals go through TC and end up in VCA, the signal path to the potentiometers is the same as the level in all channels.
From there on the thing breaks down, I tried to put resistors 2.7kΩ to fader in the 3rd channel (maybe I ran into a faulty 10kΩ fader alps component, I don't think for sure but you never know, ive try faders from other channel with same results), but that's how it cuts (drops level) and signal from the entrance probably because of TC.
Because I am in the process of changing the TCs (I have a genuine toshiba) it seems extreme to me because I think they either work or they don't work, I don't think and I don't know that linear-logarithmic behavior changes.
Keep in mind that the channel outputs a clear signal and when fully raised the potentiometer gives the same level as the rest.
So does the VCA or the TCs justify such behavior since the signals (1-2 and 3-4) go there in pairs?
PS mute transistors etc I've checked them, I don't have an smd to change them but it doesn't make sense since they measure correctly and the behavior of the channel doesn't change with or without them and the ground is where it should be. As are the supply voltages listed in the schematic.
Sorry for my bad english, cheersm have a nice day.
Channels 1-2-4 operate logarithmically. Channel 3 behaves linearly.
Changed all the faders (as I also have another mixer for a donor, logarithmic not linear), trim, bass, mid, treble, fresh solder everywhere.
The strange thing now, the signals go through TC and end up in VCA, the signal path to the potentiometers is the same as the level in all channels.
From there on the thing breaks down, I tried to put resistors 2.7kΩ to fader in the 3rd channel (maybe I ran into a faulty 10kΩ fader alps component, I don't think for sure but you never know, ive try faders from other channel with same results), but that's how it cuts (drops level) and signal from the entrance probably because of TC.
Because I am in the process of changing the TCs (I have a genuine toshiba) it seems extreme to me because I think they either work or they don't work, I don't think and I don't know that linear-logarithmic behavior changes.
Keep in mind that the channel outputs a clear signal and when fully raised the potentiometer gives the same level as the rest.
So does the VCA or the TCs justify such behavior since the signals (1-2 and 3-4) go there in pairs?
PS mute transistors etc I've checked them, I don't have an smd to change them but it doesn't make sense since they measure correctly and the behavior of the channel doesn't change with or without them and the ground is where it should be. As are the supply voltages listed in the schematic.
Sorry for my bad english, cheersm have a nice day.
update, ive changed ic101 - 102 - 103, remove q803 for test pruposes and i get same results.
ps. pots are brand new. i have all voltages correct, grounds are solid everywhere, i tested pin to pin ic's connection on board. i dont know where is the fault.
ps. pots are brand new. i have all voltages correct, grounds are solid everywhere, i tested pin to pin ic's connection on board. i dont know where is the fault.
unfortunately I don't have an oscilloscope at this moment. My measurements are currently done with a generator from a 4-channel sound card where I give a 500Hz tone and measure level.
In the IC's before faders level are the SAME on all channels. Up to the inputs of the potentiometers the levels are the same.
Today I changed IC101 - 102 - 103 where I got them from another mixer that has a problem elsewhere, specifically the DJM3000 as well as the potentiometers VR411-412 etc. are from him. Nothing changed unfortunately.
keep in mind, I'm thinking of going to get other faders, but if the 3rd one was different, the input channel would become linear. but no. ch3 remains linear.
In the IC's before faders level are the SAME on all channels. Up to the inputs of the potentiometers the levels are the same.
Today I changed IC101 - 102 - 103 where I got them from another mixer that has a problem elsewhere, specifically the DJM3000 as well as the potentiometers VR411-412 etc. are from him. Nothing changed unfortunately.
keep in mind, I'm thinking of going to get other faders, but if the 3rd one was different, the input channel would become linear. but no. ch3 remains linear.
Have a look at page 21 of the service manual.
You will notice that the wiring at the connectors of the faders are different between CH3 & CH4.
I don't know if you only replaced the faders or the complete PCB.
This might give you a clue.
You will notice that the wiring at the connectors of the faders are different between CH3 & CH4.
I don't know if you only replaced the faders or the complete PCB.
This might give you a clue.
I'm out of ideas, except to propose you asking at Pioneer forums:
https://forums.pioneerdj.com/hc/en-us
https://forums.pioneerdj.com/hc/en-us
problrem solved. one ground point and signal pad on IC103 was interrupted.
I found it with microscope.
Thank all of you for help!!
I found it with microscope.
Thank all of you for help!!