Hi,
I am working on the above mentioned non powered mixer. The problem with this mixer is as follows:
I connected a CD player into channel 1 of the mixer, connected the master output to a power amp. I turned on the CD player, the mixer and the power amp. It was working fine and the output master LEDs on the mixer indicating about halfway. Then about one hour later, I heard a "thud" sound for about a split second and when it happened, I realised that the red "mute" led on all the channel came on and the master output LEDs went blank. This was only for a split second and everything came back to normal after that. This repeated about 3 to 4 times within about 2 minutes interval. Then suddenly all the "mute" leds came on and remained constantly ON. The output LEDs disappeared totally and I hear a motor sound from the speakers. I measured the voltage across the master output cable and it was reading (-9V DC). I turned off everything and after half an hour, I ON back everything. Then after about one hour, the same thing repeated. Can someone give me a clue on what can cause this. I realised that the heat sink housing the 2 voltage regulator was very hot. Pls assist
Thanks
Carlos
I am working on the above mentioned non powered mixer. The problem with this mixer is as follows:
I connected a CD player into channel 1 of the mixer, connected the master output to a power amp. I turned on the CD player, the mixer and the power amp. It was working fine and the output master LEDs on the mixer indicating about halfway. Then about one hour later, I heard a "thud" sound for about a split second and when it happened, I realised that the red "mute" led on all the channel came on and the master output LEDs went blank. This was only for a split second and everything came back to normal after that. This repeated about 3 to 4 times within about 2 minutes interval. Then suddenly all the "mute" leds came on and remained constantly ON. The output LEDs disappeared totally and I hear a motor sound from the speakers. I measured the voltage across the master output cable and it was reading (-9V DC). I turned off everything and after half an hour, I ON back everything. Then after about one hour, the same thing repeated. Can someone give me a clue on what can cause this. I realised that the heat sink housing the 2 voltage regulator was very hot. Pls assist
Thanks
Carlos
It's not a good habit to try to switch on any equipment if it failed.
I'm always surprised that some do switch on the equipment after it failed. Components that go bad do not regenerate by them self.
The usual method id to find out what went wrong and remedy it.
The schematic has been offerd via Tanya (do a search here) and as you stated; the psu is probably either gone or some opamps or caps are fried.
Get the schematic first and then search your way through the mixer.
Do not hesitate to come back with your results.
Good luck
I'm always surprised that some do switch on the equipment after it failed. Components that go bad do not regenerate by them self.
The usual method id to find out what went wrong and remedy it.
The schematic has been offerd via Tanya (do a search here) and as you stated; the psu is probably either gone or some opamps or caps are fried.
Get the schematic first and then search your way through the mixer.
Do not hesitate to come back with your results.
Good luck
I have had very similar incident happen to my Mackie 32-8 just recently!!
Such things as channels would stop working and the solo would stop working altogether, as well as all of the led's going haywire where all attributed to bad cable connectors.
Many times I have had to just take the cover off and reseat the cables a few times, and then all was well until the next time.
This time around I channels again stopped working and the master out started to make motorboating sound and slammed the meters fully to the left.
Sometimes pounding on the board and/or turning it off would reset this malfunction but this time it did not.
And as you can imagine I was quite worried as this was right in the middle of a major recording project and where was I going to get another one of these, let alone how much would it cost!!!
This time (the second time I have done this) I completely stripped the board from the case and cleaned all 1000 or so switch's, controls and jacks.
Upon inspecting the boards I had noticed a few solder connections that had started to crack and some that were just terribly soldered.
So, I redid all of the solder points on all of the connectors and a few other ones as well just to be sure.
I re-assembled everything and all was well after working the controls in and then all of a sudden it did it again!!
So I took out the master buss section and hooked it up, just all by itself, and found the it was intermittent as I moved the board around.
I was thinking that it was a cracked trace but I could not find any.
Then Finally, The fault revealed itself, it was a bad power connector that was feeding the 5v supply to the board.
This is a short 3 wire connector besides the 7 pin ones that carry the rest of the supply voltages from the power distribution board.
I don't know if your board has this type configuration.
Also one other time prior, Some caps or something on that board gave out and shorted the power supply and burned the board badly.
It was so bad that it there was nothing but a black carbon spot on the board, and that it was conducting and shorting out the supply.
This caused the whole master section to be completely dead!!
So, Just like a dentist would do, I ground out all of the black decay and repaired the traces and replace the caps and all was well until this time around.
What I did to fix it was to remove the the pins from the connectors and solder the wires directly to their respective pins and re-insert them to the carrier,
I also did this to the main supply feed carrying the other voltages as well.
The problem is that the wires are pressed into knife blades on the top of the pins and they were not a very mechanically solid connection.
I hate this type of connector and they have been the cause of failure in many pieces of my equipment through the years!
After I got it all back together everything is now working perfectly as it was when it was new 20 years ago.
And with no blown opamp's as I had thought there were was, as I leave the thing on for 24/7 and have done so for the last 5 1/2 years!!!
I am the original owner since 1994 as well.
These boards are not easy to work on but with a bit of patients you can fix it.
It took me nearly 2 months before I finally found and fixed the problem this time, as I had to take some of boards in and out at least 5 or 6 times, and there are a lot of screws and nuts holding those things in there!!!!
Also, While I had the pins out to be solder they were black with tarnish and I am sure this attributed to the problem as well.
So, I sanded each one lightly to clean them with some 600grit (or finer) emery paper, after, I had soldered them to the wires.
I also reshaped them to have more spring force on the contact area of the mating pin.
I know you can find the schematic on line to your board easily as I have a copy, Because I could only find but bits and pieces to my board.
Luckily I just happened to run across a guy (at the same time) that had them and he sent me a copy! 🙂
Else you can get a hold of Mackie and they will send them to you, I believe free of charge.
Cheers and Good luck to you, as they really are very fine boards !!!
jer 🙂
Such things as channels would stop working and the solo would stop working altogether, as well as all of the led's going haywire where all attributed to bad cable connectors.
Many times I have had to just take the cover off and reseat the cables a few times, and then all was well until the next time.
This time around I channels again stopped working and the master out started to make motorboating sound and slammed the meters fully to the left.
Sometimes pounding on the board and/or turning it off would reset this malfunction but this time it did not.
And as you can imagine I was quite worried as this was right in the middle of a major recording project and where was I going to get another one of these, let alone how much would it cost!!!
This time (the second time I have done this) I completely stripped the board from the case and cleaned all 1000 or so switch's, controls and jacks.
Upon inspecting the boards I had noticed a few solder connections that had started to crack and some that were just terribly soldered.
So, I redid all of the solder points on all of the connectors and a few other ones as well just to be sure.
I re-assembled everything and all was well after working the controls in and then all of a sudden it did it again!!
So I took out the master buss section and hooked it up, just all by itself, and found the it was intermittent as I moved the board around.
I was thinking that it was a cracked trace but I could not find any.
Then Finally, The fault revealed itself, it was a bad power connector that was feeding the 5v supply to the board.
This is a short 3 wire connector besides the 7 pin ones that carry the rest of the supply voltages from the power distribution board.
I don't know if your board has this type configuration.
Also one other time prior, Some caps or something on that board gave out and shorted the power supply and burned the board badly.
It was so bad that it there was nothing but a black carbon spot on the board, and that it was conducting and shorting out the supply.
This caused the whole master section to be completely dead!!
So, Just like a dentist would do, I ground out all of the black decay and repaired the traces and replace the caps and all was well until this time around.
What I did to fix it was to remove the the pins from the connectors and solder the wires directly to their respective pins and re-insert them to the carrier,
I also did this to the main supply feed carrying the other voltages as well.
The problem is that the wires are pressed into knife blades on the top of the pins and they were not a very mechanically solid connection.
I hate this type of connector and they have been the cause of failure in many pieces of my equipment through the years!
After I got it all back together everything is now working perfectly as it was when it was new 20 years ago.
And with no blown opamp's as I had thought there were was, as I leave the thing on for 24/7 and have done so for the last 5 1/2 years!!!
I am the original owner since 1994 as well.
These boards are not easy to work on but with a bit of patients you can fix it.
It took me nearly 2 months before I finally found and fixed the problem this time, as I had to take some of boards in and out at least 5 or 6 times, and there are a lot of screws and nuts holding those things in there!!!!
Also, While I had the pins out to be solder they were black with tarnish and I am sure this attributed to the problem as well.
So, I sanded each one lightly to clean them with some 600grit (or finer) emery paper, after, I had soldered them to the wires.
I also reshaped them to have more spring force on the contact area of the mating pin.
I know you can find the schematic on line to your board easily as I have a copy, Because I could only find but bits and pieces to my board.
Luckily I just happened to run across a guy (at the same time) that had them and he sent me a copy! 🙂
Else you can get a hold of Mackie and they will send them to you, I believe free of charge.
Cheers and Good luck to you, as they really are very fine boards !!!
jer 🙂
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