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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Arthur Hale on August 19, 2011, 01:33:46 PM
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Hey guys,
I recently bought a used MacroTech 2402 for cheap, and ended up running it at 4R Bridge powering two 18TBX100 loaded WSX's. Everything was well for awhile until BWARGHHHH, the output of the macrotech suddenly got VERY distorted and lower in level. It sounded like I suddenly turned on a limiter with -20db of gain reduction on the bass. Terrible noise. I ran back to my amps and I turned the amp off for a minute and powered back on and everything was OK for a minute (I did it in a hurry so i could not see what the lights looked like on the amp). Everything was OK but every 10-15 minutes the RIGHT ODEP light would go out and all output would get immediately cut. If i turned down the level of knob #1 (#2 was all the way down the entire time due to being bridged), the odep light would slowly fade back on and once completely lit again, i could turn back up the gain and it owuld play fine for another 10 or 15 minutes until it would cut audio and put out the right channel ODEP. Inbetween doing this, I was blowing fuses at the venue left and right. Eventually as a workaround to both issues, to just get through the gig, i ended up turning the gain down to about 65% and this issue never happened again and I never blew any more fuses. All the while the sides of the amp are HOT AS HELL to the touch. I even removed the filters at one point to make sure they weren't clogged and the issue persisted.
Now, I am VERY curious as to what the source of my issues were. This is the USA with 120v, amp was on a dedicated (or so the venue told me) 20A circuit with nothing else on it, but I don't believe the dude.
Was this overheating?
Or was me blowing fuses and this audio cutting issue related?
Was this lack of juice and the macrotech responding in its way?
Or did I just pick up a bad macrotech that needs repaired?
Any help would be GREATLY appreciated guys
THANK YOU!!
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Read the rules, fix your display name.
Thank you for your cooperation.
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What is your output wiring like?
It almost sounds like you have a short to ground on the negative side (the right channel) of the amplifier. Is there a metal patch panel? Any 1/4" plugs? Frayed wires? The symptoms are consistent with a very low impedance load on one of the channels.
GTD
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Hey guys,
I recently bought a used MacroTech 2402 for cheap, and ended up running it at 4R Bridge powering two 18TBX100 loaded WSX's. Everything was well for awhile until BWARGHHHH, the output of the macrotech suddenly got VERY distorted and lower in level. It sounded like I suddenly turned on a limiter with -20db of gain reduction on the bass. Terrible noise. I ran back to my amps and I turned the amp off for a minute and powered back on and everything was OK for a minute (I did it in a hurry so i could not see what the lights looked like on the amp). Everything was OK but every 10-15 minutes the RIGHT ODEP light would go out and all output would get immediately cut. If i turned down the level of knob #1 (#2 was all the way down the entire time due to being bridged), the odep light would slowly fade back on and once completely lit again, i could turn back up the gain and it owuld play fine for another 10 or 15 minutes until it would cut audio and put out the right channel ODEP. Inbetween doing this, I was blowing fuses at the venue left and right. Eventually as a workaround to both issues, to just get through the gig, i ended up turning the gain down to about 65% and this issue never happened again and I never blew any more fuses. All the while the sides of the amp are HOT AS HELL to the touch. I even removed the filters at one point to make sure they weren't clogged and the issue persisted.
Now, I am VERY curious as to what the source of my issues were. This is the USA with 120v, amp was on a dedicated (or so the venue told me) 20A circuit with nothing else on it, but I don't believe the dude.
Was this overheating?
Or was me blowing fuses and this audio cutting issue related?
Was this lack of juice and the macrotech responding in its way?
Or did I just pick up a bad macrotech that needs repaired?
Any help would be GREATLY appreciated guys
THANK YOU!!
This looks like overheating to me. Pull the lid on this amp. You would not believe how bad heat sinks and fans get clogged and the blades on fans get gunked up. Clean the fans/blades like new. Blast the crud out of the amp and make sure the heat sinks are all open for cooling. A paint brush works well to loosen up the crap off of everything. Every season I pull my amps out of the racks and open them up
and clean them real well inside. This will eliminate failures and maybe might clear up your issues. Also you can pull cables off PCB connectors etc and re-seat them all on their connectors on the PCB connections. Good luck to you