Can someone please tell me whats going on with my amp

[suteman 10+ year member]

it was set to measure 12v on the dmm. did i do it wrong?

 

[bubbagumper6 5,000+ posts]

it was set to measure 12v on the dmm. did i do it wrong?

Somehow, yes. Set it to measure DC voltage then measure the voltage on your battery, I'm only telling you to do this part so you can verify you have it on the correct setting, you should get the same results as before. Then without changing anything, go to the amplifier and with power and ground cables still connected to it, put the DMM leads on the amp terminals to measure the voltage there. Make sure your getting the DMM probes onto metal, just use your head when it comes to reading the meter. It SHOULD read the same as the battery does (both with the car on and off). If it's reading a crazy high number like 79 then make sure it doesn't say "mV" somewhere on there because that means millivolts. Post back with results.

 

[mast240 10+ year member]

there should be a setting between ac/dc voltage... and a range setting

 

[suteman 10+ year member]

so the battery is at 12.79 when off and 14.05 when on and the amp stays at 2.4 when the car is both on and off

 

[mast240 10+ year member]

2.4 votls???

 

[bubbagumper6 5,000+ posts]

so the battery is at 12.79 when off and 14.05 when on and the amp stays at 2.4 when the car is both on and off

Disconnect the amplifier and retest at the battery.

 

[suteman 10+ year member]

ok i disconnected the power wire the battery is at 12.89 off and 13.95 on and the amp is at 2.37v now

 

[bubbagumper6 5,000+ posts]

and the amp is at 2.37v now

This doesn't make any sense, I told you to disconnect the amplifier so it shouldn't be reading anything...because it's not connected

How are you only getting 2 volts? You're sure it's not 12.37? I told you to use your head when measuring the voltage, if you didn't already deduce, 2 volts is way way too low.

 

[suteman 10+ year member]

nope it said 2.37 V with DCV and AC was at 0.2

 

[bubbagumper6 5,000+ posts]

My only suggestion at this point is to get the amplifier to someone who knows what they're doing. Not trying to be a dick but we're getting nowhere fast. Your answers are vague and it's difficult to help someone diagnose problems when they don't have a lot of experience with electronics.

 

[suteman 10+ year member]

what? i did what you asked me to do and im telling you what the meter said im not blind it said 2.37 volts i know its low which is why i want to figure out the problem

 

[AlterEgo99 5,000+ posts]

but we always start with a DMM and measure voltage.
next, we use that same DMM to measure VAC out of the amp speaker terminals to look for a signal.

then we use that same DMM to measure resistance (ohms) of the speaker wire (disconnected from amp) to verify sub wiring.

First, completely agree with the above ^

The problem now seems to be that it looks like the amp may already be damaged and therefore, a DMM measurement at this point would be futile, no?

 

[bubbagumper6 5,000+ posts]

First, completely agree with the above ^
The problem now seems to be that it looks like the amp may already be damaged and therefore, a DMM measurement at this point would be futile, no?

Nothing in this thread has confirmed that so I wouldn't jump to that conclusion. If he still had that amplifier connected to the vehicle's electrical system and it was reading 2 volts on the terminals then I think he would be seeing some fireworks. You can't just drag the entire system voltage down to 2V and not damage things, which is why I still think that 2V reading is nonsense. Was that a reading you took from the amp while it was disconnected? (perhaps just some leftover charge from the internal caps?)

 

[AlterEgo99 5,000+ posts]

Nothing in this thread has confirmed that so I wouldn't jump to that conclusion. If he still had that amplifier connected to the vehicle's electrical system and it was reading 2 volts on the terminals then I think he would be seeing some fireworks. You can't just drag the entire system voltage down to 2V and not damage things, which is why I still think that 2V reading is nonsense. Was that a reading you took from the amp while it was disconnected? (perhaps just some leftover charge from the internal caps?)

OK, that is what I figured...I was trying to understand how the hell he could be getting a good voltage reading at the battery and then if you trace the power wire down to the amp's positive terminal, you get 2V. Seems odd to me as well.

 

[bubbagumper6 5,000+ posts]

OP, do you perhaps have a spare amplifier that you know works that you could swap out?

Can you please explain the circumstances surounding that 2V reading? Amplifier connected/disconnect, car running/off?