That doesn't inspire confidence that everything is under control. How do you KNOW that it stays in adjustment after 10 years of being moved around in an equipment rack? I like VI limiters - you hit Vbe and it folds back. No muss, no fuss.
What I think happens.
Over a period of time, the bias pots creep from their proper setting. That's why I ALWAYS cement, glue , or silicone them after making proper adjustment. And that keeps the uneducated from opening it up and "screwing around." Seems like none of the amps I've seen come from the factory with the pots secured.
Over a period of time, the bias pots creep from their proper setting. That's why I ALWAYS cement, glue , or silicone them after making proper adjustment. And that keeps the uneducated from opening it up and "screwing around." Seems like none of the amps I've seen come from the factory with the pots secured.
When bias pots creep, you get distortion. Then you go fix it. If they open, you get a LOT of distortion (class B or even C operation). Then you go fix it. If a current limit pot creeps, you might not know anything about it until the amp is on fire.
I would really like to find a source for that goop the factories use. sort of a clear/translucent red or green gel stuff that stays somewhat tacky. I found one place specified something called "Glyptol Resin" which sounds interesting.
I use one of those touch-up bottles of paint that are sold for stone-chips in car paintwork. Discontinued colours can be bought for pennies.
Adjustments of an EP2500
Does anybody have the calibration routine on the EP2500?
I can tell something is wrong with it, as the lower part of amp, the negative half is much warmer than the positive.
90 degrees C against 65 degrees C, measured on the four transitors wit an IR termometer. And it turns off after some half to one hour, 8 amp mechanical fuse goes home.
I am afraid of a current limit pot creeper... =)
I did the usuel fastening of rectifier bridges that get lose, making it a cooler.
But I need the bias procerdure and the current limit procedure.
BTW, is this a copy of a Crown amp?
Does anybody have the calibration routine on the EP2500?
I can tell something is wrong with it, as the lower part of amp, the negative half is much warmer than the positive.
90 degrees C against 65 degrees C, measured on the four transitors wit an IR termometer. And it turns off after some half to one hour, 8 amp mechanical fuse goes home.
I am afraid of a current limit pot creeper... =)
I did the usuel fastening of rectifier bridges that get lose, making it a cooler.
But I need the bias procerdure and the current limit procedure.
BTW, is this a copy of a Crown amp?
Its a copy of the QSC amp.
One of your biases is off. Ther are two bias pots. I would be very careful adjusting them. A little bit goes a long way. Also they are crappy pots and go bad frequently.
One of your biases is off. Ther are two bias pots. I would be very careful adjusting them. A little bit goes a long way. Also they are crappy pots and go bad frequently.
Either 90 or 60deg C are too hot if the amp is in idle.
This is a copy of a QSC RMX2450 so the calibration is the same if you match-up the components on the QSC diagram.
If the main 8A fuse is blowing, I suspect more than just calibration, possibly one side of the amp is down or the rail switches are misbehaving.
This is a copy of a QSC RMX2450 so the calibration is the same if you match-up the components on the QSC diagram.
If the main 8A fuse is blowing, I suspect more than just calibration, possibly one side of the amp is down or the rail switches are misbehaving.
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