help with europower ep-2500

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ep-2500

i downloaded a similar schematic.hard to follow though.i replaced the 47mf cap in this one.no luck.also checked in and out on the preamp op amps.i have signal in and out.seems to be getting lost somewhere before the main output transistors.ill pay you if you can help me fix it.i did a google search and for a similar schematic on line.i also test voltages on both channel output transistors.seem the same on both sides.you can replay to my direct email address (easier for me, and faster)
strat1953@aol.com thanks,Guy
 
Check the gain pots. I bought an EP2500 'return' from Guitar Center for about $150 a few years ago. One channel didn't work. The ribbon cable was a complete mess, so I replaced it. One channel still went occasionally 'low', but I noticed that it only happened when the gain wasn't set to max. The pot was flaky so I replaced them both with something better.

It's build quality issues like this that separate the EP2500 from the RMX2450.
 
i own a bunch of EP2500 ...i think 25 or so some of them work for permanent rental installation some other work in small pa systems that we rent in generally not high demanding applications

never had the singlest problem with them ....Trust me beyond "electrical" stress that might occure from various forms of abuse while rentals onf the most serious problems is the mechanical stress that happens from moving the amps from one place to the other often without cases
 
never had the singlest problem with them ....Trust me beyond "electrical" stress that might occure from various forms of abuse while rentals onf the most serious problems is the mechanical stress that happens from moving the amps from one place to the other often without cases

Count yourself among the lucky ones. The good news is that these amps are dirt simple and easy to work on. Fix the usual bad connection or whatever and it's good to go forever. And being a class H high efficiency amp, they will take PA abuse better than a straight class AB. The EP1500 will overheat if you push it at all even at 8 ohms. You can 'blast' 4 ohms stereo on the 2500 no probelm.
 
I've worked on these before.

Does that channel power up more slowly than the other?
Is the clip light coming on?
Apparent preamp problems are often output stage problems.
Any DC on this output? I've seen bad op amps in these. (Never changed an OTA on one of these however.)
This is a two stage amp. Is your gain loss at low level or at high level?
There have been problems with the mosfets with these.
Also any caps heating?
QSC publishes a training manual for these types of amps that discusses theory and troubleshooting, etc.
 
europower amp

a lot lower volume on the non working channel .no dc on the output could an output be bad a loading down the preamp? never blew a fuse maybe you could direct me where to check on the board (cap locations for both sides or resistor numbers) ? ill try to see where the signal stops. hard to read the print i have and its not the same model.
Guy
 
First!!!

I would check the dip switch settings on the back and make sure they're set identically for both channels.
If the clip lite is not on after the amp powers up, you probably don't have a blown channel.
Verify the lugs are connected to the proper terminals at the back of the module. (The color is identified on the board.)
Does the lower gain channel have any distortion?
Have you looked at your waveform with a scope?
 
Behringer also uses some sort of glue/goop on ribbon cables to hold them down. I have seen that goop seep into the contacts and cause issues. Had some amps that had odd problems and every time i tore it apart the problems would change. I swapped out that ribbon cable and all the problems went away. after taking the old cable apart i found the glue inside the connectors coating the pins.


Zc
 
The QSC part number for the training manual for these types of amps is TD-000098-00. Last I checked they wanted $15 for a download. Might be worth it if you service a lot of these amps. Covers the RMX850, 1450 and 2450. There are at least 4 manufacturers cloning these amps out there.
 
Most fascinating thing I ever saw!

Brad Sambrano (of QSC) was throwing a dead short on the output of an RMX series amp while it was operating.
Now you would think the amp would fry. The only thing that happened was the sine wave collapsed (of course) and the clip lite came on.
He did this several times with no ill effects. Unbelievable!
It worked because the current limit pots (positive & negative) were set properly.
Now I know why other manufacturers clone these amps.
 
A long time ago I repaired a Carver PM1.5, and put it on the burn-in bench with a sine wave not quite to clipping, and appropriate load. It would thermal and try to protect itself after a few minutes. But everything seemed to be OK. I called Carver to ask what I could do. They told me, "Quit feeding it a sine wave. It was designed to amplify music, not sine waves." Sure enough, I could crank music into it as hard as I wanted.
 
Part of the QSC calibration procedure calls for setting the "foldback Current Limit" this is done by running the amp at full power into a 2 ohm load, then shorting the output and quickly adjusting the setting so that during a short it reduces the AC line current draw down to a specific range. scary as hell doing it for the first time after you have just repaired one of these buggers! I had to build a special jig to do the test with.


Zc
 
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