help with europower ep-2500

[strat1953]

one channel is lower than the other. looks to be somewhere in the preamp.no blown fuses or burned parts ?? ill paypal a fee to who ever helps me solve this,Guy strat1953@aol.com

[llwhtt]

I don't suppose there's a 47pf capacitor in there, LOL. Do you have a schematic?

Craig

[strat1953]

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

[sakis]

check and or remove the limmiter section of the faulty amp to find out if something wrong there

measure with volt meter voltage not in reference with ground but in reference with the working chanel ....0 volts menas no probs any other means trouble

[wg_ski]

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.

[sakis]

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

[wg_ski]

Originally Posted by sakis

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.

[LAJ]

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.

[strat1953]

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

[strat1953]

the clip lite was on when i first powered amp not any more