10 replies to this topic

[acarr87]

Hey guys, got an issue with my pdx 1.1000.. Tested the power wire going to it out of the amp with the car off and on accessories, getting 12v, once connected the second that the amp turns on, the power going through the wire at the amp is only 9.5v?!

Is the amp cactus? As soon as you get to a decent level of loud, it gets the red led and goes into protect, I'm assuming this may be voltage related?

Any thoughts are appreciated!

Cheers

[Benno25]

Maybe check the negative out of the amp to the car chassis? Sounds like that is maybe not a good connection?

Cheers
Benno

[acarr87]

Oh, it's running a type x 12 (dual 4 ohm) if that helps (1 coil per pdx plug)

Thanks for your reply, tried 3 or 4 different ones, even straight off the battery (bot mounted), still same result

[Benno25]

Righto, double check to make sure you have 0 volts across the negative battery terminal and the negative power terminal on the amp. That being the case, check your positive power wire to the amp to check if the voltage drop you are seeing is caused by the power cabling or the amp. That will isolate if your power cabling is causing issues or if the fault is somewhere else.

Cheers
Benno

[TMM]

How are you testing the voltage? Across the terminals on the amp? Try connecting the +ve probe to the +ve terminal on the amp and the -ve probe to the -ve terminal of the battery.

If you are still getting getting a reading of 9.5v the battery is cactus or the amp is drawing too much power for that cable due to a fault or otherwise.

If you get a normal reading using the above test, but it reads 9.5v when you probe across the amp terminals then you have a grounding problem.

[Mr. Drifter]

How are you testing the voltage? Across the terminals on the amp? Try connecting the +ve probe to the +ve terminal on the amp and the -ve probe to the -ve terminal of the battery.

If you are still getting getting a reading of 9.5v the battery is cactus or the amp is drawing too much power for that cable due to a fault or otherwise.

If you get a normal reading using the above test, but it reads 9.5v when you probe across the amp terminals then you have a grounding problem.

Surely it'd be the other way around? or if it's 9.5v on one side, it'd be like that on both? cause the current going into the amp through positive (which from memory isn't the direction is goes, but still) would have to run through the amp to get back to the battery? so either way it'd be 9.5? /talking out of my ass a little

[TMM]

Surely it'd be the other way around? or if it's 9.5v on one side, it'd be like that on both? cause the current going into the amp through positive (which from memory isn't the direction is goes, but still) would have to run through the amp to get back to the battery? so either way it'd be 9.5? /talking out of my ass a little

Measuring from +ve amp to -ve batt is measuring the voltage drop across the power cable and the battery itself - therefore ignoring any voltage drops caused internally by the amp, or by the grounding of either the amp or battery. If you get a voltage drop here it can only possibly be caused by the battery itself or the +ve power cable.

Measuring across the terminals on the amp will show up the total voltage drop in the entire system. Therefore if no voltage drop is present in the first test, but there is a voltage drop in the second test, you know you have a problem either with the grounding of the amp or battery.

edit: I guess, you could also probe between the battery -ve terminal and amp -ve terminal, if it goes up to ~2.5v under load then you know for sure that it's a ground cable.

Edited by TMM, 12 June 2012 - 10:58 PM.

[Mr. Drifter]

Measuring from +ve amp to -ve batt is measuring the voltage drop across the power cable and the battery itself - therefore ignoring any voltage drops caused internally by the amp, or by the grounding of either the amp or battery. If you get a voltage drop here it can only possibly be caused by the battery itself or the +ve power cable.

Measuring across the terminals on the amp will show up the total voltage drop in the entire system. Therefore if no voltage drop is present in the first test, but there is a voltage drop in the second test, you know you have a problem either with the grounding of the amp or battery.

edit: I guess, you could also probe between the battery -ve terminal and amp -ve terminal, if it goes up to ~2.5v under load then you know for sure that it's a ground cable.

Ah, I see. My bad thanks for correcting

[shiny_car]

As above, suspect a power supply issue rather than the amp itself. If it's not a groundwire issue, then the positive powerwire may have a bad connection along its path (with POS battery terminal or into/out of fuseholder). Also, cheap glass 5AG/AGU style fuses can fail, even though the fuse 'wire' looks intact; what sort of fuse do you have? The actual fuse could also be poorly connected to the fuseholder.

[SQXPRT]

Don't use glass fuses for amps.

use Maxi Blade or AGU fuses.

Even circuit breakers fail sooner than solid wire.

[shiny_car]

use Maxi Blade or AGU fuses.

AGU are 'glass' 5AG fuses.

I presume you mean MIDI or ANL instead.