todddchi

iTrader: (3)

Hi all,

I'm fighting through some system issues, basically what is happening is my Memphis amp is seems to be becoming easier and easier to put into protection mode.

At day one the car was configured with 2ohm fronts, 4 ohm rears, and 1 ohm sub load. The memphis is rated to handle 2 ohm 4 channel and 1 ohm sub channel, so it is in spec. At day one the amp never shut down, although the sub channel would easily shutdown if I overdid it. I figured that made sense, as it was a 1 ohm load.

Now, same configuration, same speakers, same everything, the amp is on occasion going into full protection mode, shutting all channels down.

Basically, like I said it's like the protection circuit is becoming more and more conservative.

I've tried individually disconnecting each speaker, with no effect. So I don't have a bad driver or shorted connection. Power and grounds are still good.

Is there something in the amp that can fail over time? I've never heard of a problem like this. I love the amp (and they are pricey) so I'd probably have it fixed. I just don't know if it is even possible.

habeba86

iTrader: (2)

Is the ground still good? Rusty at all?

95bat

iTrader: (1)

First two things that come to my mind are low voltage or amp over heating. Memphis amps LOVE high voltage, they don't like to work off the 11 volt range.

How long does it take to come back on? After it comes back on, how long does it take to shut off again? Is it a hot day when it shuts down? What other accessories are running (AC, lights, etc) when the stereo shuts down?

todddchi

iTrader: (3)

Well first off, I realized the amp is more likely to go into shutdown at low voltage, because it is definitely more sensitive when the car is not running.

I also improved the cooling space, and saw some improvement. So you are right, these are both contributors.

But my connections are not suspect, and far as I can tell (voltmeter) my charging system is working as typical. On full hits the lights do not flicker, the battery is a little over 2 years old at this point.

So I guess if the battery is weaker that might explain some of it.

What I don't understand is that I ran the amp in the original state (not so good cooling and heavy loads) for well over a year with no problems at all. This summer it started acting up, having never previously had any shutdown issues, and it seems to be getting more and more sensitive.

It shuts down in one of two ways. Sometimes it'll clip shut off briefly, for a few moments, then come back on. Sometimes it'll clip shutoff totally, and be dead for awhile. Power cycle or long cooling resets it.

I know my connections are good and no speakers are blown. My only two suspicions are a more touchy shutdown circuit (for whatever reason) or possibly overall lower voltage getting to the amp.

95bat

iTrader: (1)

It sounds like low voltage to me... usually when amps shut down from low voltage they'll either come back on in a few seconds or you can turn off the stereo then turn it back on and the amp will come on. They'll stay on after that if you have the volume low. If it is a heat issue, if you turn the amp back on it will shut down again a lot quicker.

From what I've read about memphis amps, the more likely culprit is low voltage. 5 channels draw a lot of current...

todddchi

iTrader: (3)

Well, based on the above comments I went through my connections in better detail, and found my terminal was corroded sandwiched in between the post clamp so it wasn't visible without tearing it down.

Cleaned that sucker up and it seems to be running back on par.

I guess it's good that the protection circuit shuts the amp off at clipping, even if the clipping is happening from low current - it just made for kind of an odd behavior set.

Tks!

95bat

iTrader: (1)

Glad to hear its working again!