DiyMobileAudio.com Car Stereo Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Last fall before parking my car for winter I removed the Memphis PRX 5.550 5 channel Amp and sub. Disconnected battery, took pictures, and removed them.
Got the car with this setup already installed.
This spring went to just put them back the way they were and the sub didn't work. Looked at the head unit settings and turned sub to on. Still nothing.
Fuses are good. Tried the only spare speaker I have from the garage radio, an old boom box speaker. It barely made any noise.
The sub is a JL 10" , in a JL box, I think. Running at 4 ohms
 

·
Registered
Joined
·
1,198 Posts
Last fall before parking my car for winter I removed the Memphis PRX 5.550 5 channel Amp and sub. Disconnected battery, took pictures, and removed them.

Got the car with this setup already installed.

This spring went to just put them back the way they were and the sub didn't work. Looked at the head unit settings and turned sub to on. Still nothing.

Fuses are good. Tried the only spare speaker I have from the garage radio, an old boom box speaker. It barely made any noise.

The sub is a JL 10" , in a JL box, I think. Running at 4 ohms
Same amp? I've had 2 Memphis amps with problems, 1 4 channel lost a channel (mc 4.75), 1 prx 1500.1 went into a never ending protect cycle. To their credit, they fixed the 4 channel and replaced the 1500.1. I'd hook the sub up to a home system to narrow down your problem a bit.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
Same amp? I've had 2 Memphis amps with problems, 1 4 channel lost a channel (mc 4.75), 1 prx 1500.1 went into a never ending protect cycle. To their credit, they fixed the 4 channel and replaced the 1500.1. I'd hook the sub up to a home system to narrow down your problem a bit.
yes same amp. all I did was remove then install. how do I hook up the sub to a home system? Meaning, I don't have a home audio system. Just a 4k TV and soundbar with wireless sub. A nice PC and also a really old stereo.
 

·
Registered
Joined
·
1,198 Posts
yes same amp. all I did was remove then install. how do I hook up the sub to a home system? Meaning, I don't have a home audio system. Just a 4k TV and soundbar with wireless sub. A nice PC and also a really old stereo.
Got a friend with a car or home system?
 

·
Registered
Joined
·
376 Posts
Try turning the gain knob min/max quickly many times. Maybe the pot developed a poor connection from sitting.

If that doesn't work, hook up a voltmeter to the amp and play a sine wav and make sure you're getting decent voltage from the amp channel.


Sent from my Pixel XL using Tapatalk
 

·
Registered
Joined
·
8 Posts
Discussion Starter #6 (Edited)
Try turning the gain knob min/max quickly many times. Maybe the pot developed a poor connection from sitting.

If that doesn't work, hook up a voltmeter to the amp and play a sine wav and make sure you're getting decent voltage from the amp channel.


Sent from my Pixel XL using Tapatalk
So measure DC volts. black to negative, and red to the positive sub output terminals? I read that on JL's site.
 

·
Registered
Joined
·
316 Posts
So measure DC volts. black to negative, and red to the positive sub output terminals? I read that on JL's site.
You will measure AC volts at the speaker output terminals on the amp. In this case, channel 5 for the sub. You can also measure the impedance of the sub with it disconnected.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #8
tested the sub, it works.
no voltage at sub out on amp.
are there any settings in the head unit that might be the problem?
they were reset after taking the battery out for winter.
I just don't understand, all I did was take them out, and put them back the way they were.
 

·
Registered
Joined
·
185 Posts
Did you take the fuse out of the + 12VDC wire connected to the battery? If so, put it back in, if not you may have popped it.

Do you have a multimeter? Check for +12VDC to the amp power terminal, and make sure you have +12VDC to the remote turn on terminal when the HU is powered on.

If no 12V, check the red to a nice bare bolt/metal. Ground may be bunk/corroded.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #10
Did you take the fuse out of the + 12VDC wire connected to the battery? If so, put it back in, if not you may have popped it.

Do you have a multimeter? Check for +12VDC to the amp power terminal, and make sure you have +12VDC to the remote turn on terminal when the HU is powered on.

If no 12V, check the red to a nice bare bolt/metal. Ground may be bunk/corroded.
Amp is getting power, the other 4 speakers work.
there is a sub signal IIRC that looks like a phone jack. is there a way to see if thats sending a signal to the amp?
 

·
Registered
Joined
·
1,531 Posts
Sounds to me like your amp isn’t getting signal sent to the sub channel. Take a known working RCA from one of the other known good working channels such as a full range or midbass (preferably) channel nearby and plug that RCA into the sub channel. Play the music again and if the sub plays than you have no sub signal from your HU or possibly bad RCA. If the sub channel still doesn’t play, well than you may have a bad amplifier sub channel or blown amplifier fuse.
 

·
Registered
Joined
·
376 Posts
I have never understood taking your sub out for the winter. I've always just ran them.
Me neither.

"A season without bass is like a year without sunshine."

Sent from my Pixel XL using Tapatalk
 

·
Registered
Joined
·
84 Posts
I have never understood taking your sub out for the winter. I've always just ran them.
thats super helpful


since you know you have ground and power and rem //
take one set of rca that make sound and move them to the sub ins//
if you get sub then// you need to look at the hu// no sound is amp or sub issue// there should not be a 2nd fuse for the amp just one fuse// and you have power
 

·
Registered
Joined
·
180 Posts
there is a sub signal IIRC that looks like a phone jack. is there a way to see if thats sending a signal to the amp?
An RJ13 is typically a remote control for bass boost. If there is something connected you will likely have a controller with a small knob installed somewhere to allow you to increase the bass. It is not a signal input. Do you have a photo you could post?
 

·
Registered
Joined
·
316 Posts
An RJ13 is typically a remote control for bass boost. If there is something connected you will likely have a controller with a small knob installed somewhere to allow you to increase the bass. It is not a signal input. Do you have a photo you could post?
Check this. Also, how many sets of RCA cables were plugged into the amp? I'm wondering how the sub channel gets signal? If it's only two sets, you might have bumped the input selector switch that reads, "2Ch | 4Ch | 5Ch"
 

·
Registered
Joined
·
8 Posts
Discussion Starter #17
Check this. Also, how many sets of RCA cables were plugged into the amp? I'm wondering how the sub channel gets signal? If it's only two sets, you might have bumped the input selector switch that reads, "2Ch | 4Ch | 5Ch"
3 sets, front, rear, sub. I really don't think I bumped it last year before removing it. but it was set to 2ch. switching it around didnt help.

Yes, thank you, that plug is for the remote gain.

the amp has 3, 30 amp fuses. and theres a big inline one for the main power, at the battery.

I will try the RCA swap. Thank you everyone for the replies!

I removed them because my car was in danger of being broken into where I stored it.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #18
You will measure AC volts at the speaker output terminals on the amp. In this case, channel 5 for the sub. You can also measure the impedance of the sub with it disconnected.
Why wouldn't any voltage show at any of the outputs? F/R speakers and sub out.

The RCA cables are all fine.
 

·
Registered
Joined
·
185 Posts
Do you have any friends with a system or a car audio dealer around you? I think you need to try your amp in another car, another amp in yours, ask a car audio place to test it, or ask them to troubleshoot. If you have no output at all, but all voltages are present on the inputs, you likely have a bad amp.

If you have +12VDC, Ground, and Rem all working, but no output, I would say the amp is bad. Nothing else would account for the symptom of power lights, all power signals, but no output on any speaker. The only other thing is if you have a phone or other device you can get a RCA connection to plug into the amp's inputs to bypass the headunit.
 

·
Registered
Joined
·
316 Posts
... The only other thing is if you have a phone or other device you can get a RCA connection to plug into the amp's inputs to bypass the headunit.
This was what I was thinking for your next test. You'll need an RCA to aux (1/8" jack) adaptor to plug into your phone, tablet or laptop.

Someone mentioned turning a dial in case it had corroded over the winter. Do this with the bass knob and the RCA input selector switch. Looking at the amp, I don't see any gain adjustments. Does it have potentiometers (knobs) to assist the input gain?

If this is still not working, post a picture of your setup.

Edit, I found a picture with the gain adjustments under the top cover. Did you open the cover? There's also a subsonic filter that could have been bumped.
 
1 - 20 of 21 Posts
Top