Dear gentlemen,
Forum newbie here...
I've got a mixer and/or PSU problem that's beginning to make me want to pour out some gasoline on this mixer and PSU and throw a match!
Background facts:
a) Purchased MX9000 mixer brand new
b) 3 weeks later (Saturdays only... about 20 hrs total) PSU gave up and was returned for warranty service
c) Upon return, PSU ran for 3 hours and caused a short circuit, tripping the main wall 10A (120VAC) breaker. Note: This short is present EVEN if the PSU is OFF!
d) Inspected PSU insides. First warranty job was horrid. Badly done. Capacitor (C17) 100uF 35V 85°C(M) is bulged at the top.
e) From local and online advise, replace ALL caps (with top Panasonics) and all 5 regs. Stock LM350-3A regs replaced with premium LM338T-5A regs; stock LM317-1.5A reg with premium LM350-3A reg; stock 7812-1A with premium MC78T12-3A reg.
f) Inspected MX9000 mixer, as a burnt smell came from it.
g) Found out mixer's Output PCB Euro07 PCB (PCB820099RevB) has two burnt tracks (same net, 1 on each side).
h) Carefully removed burnt tracks and even more carefully replaced with tracer wire.
i) Reassembled everything and connected alone. MX9000 and PSU turns on.
Now here's the problem:
Whenever I connect anything to the mixer that is grounded (i.e.: grounded, 3-prong CD player, etc., etc.), NO MATTER if the PSU is OFF, the main wall 10A (120VAC) breaker trips!
I disconnected everything again and the mixer and PSU turn on.
If I even touch the mixer with a 1/4" plug from ANY grounded gear, POP!
I turned off the power strip, turned off the PSU and connected a grounded CD player. I turn on the power strip and POP!
Tried another thing.
I connected a small, ungrounded mixer and everything turns on!!!
So, there is clearly a ground short, even though the PSU is off.
Electrician assessed my electrical instalation and all is ok.
Any ideas?
Someone suggested maybe a rectifier diode inside the PSU was at fault. Can this cause this behaviour?
I made a lot of different scenarios with different equipment and different jacks on the mixer. Final word: If the connected gear is grounded, a big short circuit will result, even if the PSU is off.
What can I check? Could it be the mixer, or the PSU?
Any input welcome!
Mike
Forum newbie here...
I've got a mixer and/or PSU problem that's beginning to make me want to pour out some gasoline on this mixer and PSU and throw a match!
Background facts:
a) Purchased MX9000 mixer brand new
b) 3 weeks later (Saturdays only... about 20 hrs total) PSU gave up and was returned for warranty service
c) Upon return, PSU ran for 3 hours and caused a short circuit, tripping the main wall 10A (120VAC) breaker. Note: This short is present EVEN if the PSU is OFF!
d) Inspected PSU insides. First warranty job was horrid. Badly done. Capacitor (C17) 100uF 35V 85°C(M) is bulged at the top.
e) From local and online advise, replace ALL caps (with top Panasonics) and all 5 regs. Stock LM350-3A regs replaced with premium LM338T-5A regs; stock LM317-1.5A reg with premium LM350-3A reg; stock 7812-1A with premium MC78T12-3A reg.
f) Inspected MX9000 mixer, as a burnt smell came from it.
g) Found out mixer's Output PCB Euro07 PCB (PCB820099RevB) has two burnt tracks (same net, 1 on each side).
h) Carefully removed burnt tracks and even more carefully replaced with tracer wire.
i) Reassembled everything and connected alone. MX9000 and PSU turns on.
Now here's the problem:
Whenever I connect anything to the mixer that is grounded (i.e.: grounded, 3-prong CD player, etc., etc.), NO MATTER if the PSU is OFF, the main wall 10A (120VAC) breaker trips!
I disconnected everything again and the mixer and PSU turn on.
If I even touch the mixer with a 1/4" plug from ANY grounded gear, POP!
I turned off the power strip, turned off the PSU and connected a grounded CD player. I turn on the power strip and POP!
Tried another thing.
I connected a small, ungrounded mixer and everything turns on!!!
So, there is clearly a ground short, even though the PSU is off.
Electrician assessed my electrical instalation and all is ok.
Any ideas?
Someone suggested maybe a rectifier diode inside the PSU was at fault. Can this cause this behaviour?
I made a lot of different scenarios with different equipment and different jacks on the mixer. Final word: If the connected gear is grounded, a big short circuit will result, even if the PSU is off.
What can I check? Could it be the mixer, or the PSU?
Any input welcome!
Mike
Well, good news.
Mixer is up and running.
Now I have a different problem:
Seems like the main output section inserts are reversed: tip on TRS plugs are in, Ring is out. Not so on the channel inserts, where the Tip is out.
All the main output section inserts are reversed: subgroup inserts, main inserts, etc.
Is this a Behringer mistake too, or did I somehow get the two narrow ribbon cables going to the main output board swapped?
Thanks!
Mike
Mixer is up and running.
Now I have a different problem:
Seems like the main output section inserts are reversed: tip on TRS plugs are in, Ring is out. Not so on the channel inserts, where the Tip is out.
All the main output section inserts are reversed: subgroup inserts, main inserts, etc.
Is this a Behringer mistake too, or did I somehow get the two narrow ribbon cables going to the main output board swapped?
Thanks!
Mike
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