JL amp possibly fried. Please help!

[cheeba]

Hey Guys,

I have a JL Audio 500/1 mono amplifier that isn't working properly. One day the amp started smoking (I think the ground wire came loose and touched the power somehow) and ever since then, the amp will play at normal power sometimes and then half the power at others. Is it worth taking the amp to a repair shop, does it even sound fixable or is it probably dead? Is there a way for me to test the power output using a device of some sort (multimeter perhaps)?

If anyone has any idea what could be wrong with it, it would really help me talk to the repair guys if I do decide to take it in.

Thanks!

[WhiteRabbit]

smoke is always not good, not good at all....

you can check the power output with a simple multimeter

put it in alternating current mode (AC) and place the probes on the positive and negative terminals of the speaker outputs on the amp and read what they say

[SQ Root of Watts Amp is Rated at] x [Resistance (OHM load) Amp is Rated] = Voltage the DMM Should Read

Start by having the gains down and gradually turn it up and see if you can get the correct voltage to read.

[cheeba]

Originally Posted by WhiteRabbit

smoke is always not good, not good at all....

you can check the power output with a simple multimeter

put it in alternating current mode (AC) and place the probes on the positive and negative terminals of the speaker outputs on the amp and read what they say

[SQ Root of Watts Amp is Rated at] x [Resistance (OHM load) Amp is Rated] = Voltage the DMM Should Read

Start by having the gains down and gradually turn it up and see if you can get the correct voltage to read.

Thanks for the response WhiteRabbit. I got everything you said, except that my amp is rated at 1.5 to 4 ohm stable, and isn't a certain ohm per se. How do I interpret the results at that point?

[[SMAN]]

Doesn't doing that usualy blow out the fuse in the multimeter, those are only rated for like 1/2 an amp usualy.

[WhiteRabbit]

^You're measuring voltage, not amperage.

Use the ohm rating that your speaker is connected at.

So if you have a 4 ohm driver on a 4 ohm capable amp, use 4 ohms in your calculation.

For example:

Say an amp is rated at 400 watts by 1 at 4 ohms when bridged.
The formula is sq root of watts x resistance.

400 watts by 4 ohm is 1600. Then we find the sq root of 1600 which is equal to 40.

We now know that 40 volts is equal to 400 watts.

This 40 volts will be found with the DMM. Remember to set the DMM to AC, not DC.

[[SMAN]]

ohh, i musta misread it cause i coudla swarn you told him to disconnect the driver. But the problem with this measurement is that the driver, when playing, will not hold it's resistance. Say you have a 4Ohm sub, as you start to play it, the resistance seen by the amp will fluctuate usualy from 8 - 2 Ohms. I remember my 1ohm setup when i would burp it for SPL competition would drop down to allmsot 1/3Ohms (of course this is for a microsecond. If your multimeter has a MAX HOLD option (it will hold the max value it reads) this won't be a huge issue, otherwise you gotta be quick

[cheeba]

So I got my amp fixed. I took it to a repair shop and it's been over a week and the problem hasn't returned. They told me that they just did maintenance on it and cleaned up some corrosion and resoldered some traces on the circuit board.

The boom is back!

[battlekat49]

how much did it cost you to get it repaired? ive got a 500/1 that has NO output on it at all but it powers up according to the light...