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Hey guys,

Really wondering what's the best way to diagnose my amplifier that goes into protect mode when turning up the volume. I was using the system for about a month with no hiccups. One day I was driving for about an hour with the music up, and it cut out without warning. Checked the amp and it was in protect mode.

Now when i turn up the volume and amp puts itself into protect mode soon as the bass is about to hit. I've replaced the battery because it was only charging at 50% but hasn't solved my issue. Alternator was replaced about 4 months ago.

I tried unplugging suboofer speaker wire with the RCA plugged in and the can't get the amp to protect at all.

So I'm thinking it's a wiring issue, possibly with the sub i suspect.. I'm curious, what could i start doing to better diagnose the issue?


Thanks for any help here.

My equipment
NVX JAD800.4 800w amp
Aftermarket HU
Running Polk audio component speakers in the front doors and deleted the rear speakers with 16ga speaker wire.
Sundown sd3 d2 for the sub with 12 Ga wire
Sound ordanace bass bunker box





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Hey Lenny,

Check your final wiring impedance of your sub to the amp. Also ensure you have a proper ground for your amp. It could be potentially a voltage drop or your amp just running out of power.



Are you in Canada by chance?
 

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Discussion Starter #3
Hey Lenny,



Check your final wiring impedance of your sub to the amp. Also ensure you have a proper ground for your amp. It could be potentially a voltage drop or your amp just running out of power.







Are you in Canada by chance?
Thanks for the reply man.

How would I go about checking the final wiring impedance? Forgive my ignorance, I'm a complete noob at electrical stuff. I'll double check the ground but i have it grounded to the batterys ground and is super secure.

Yes! I'm in Canada. You too?

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Thanks for the reply man.

How would I go about checking the final wiring impedance? Forgive my ignorance, I'm a complete noob at electrical stuff. I'll double check the ground but i have it grounded to the batterys ground and is super secure.

Yes! I'm in Canada. You too?

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Check the wires carefully from the amp to the sub, it sounds like they are shorting out. Make sure that there is no bare copper touching metal, and that the pos and neg wires aren't touching each other. If the wiring is good, the next step is to check the sub. You'll need a multi-meter with an ohm setting to check the resistance, but if you don't have that you can use a battery to see if the cone moves. Take the pos and neg wires from the sub and touch them to the pos and neg of a small 9 volt battery, a AA will work too. If the cone doesn't move at all don't hold the wires to the battery. If the cone doesn't move you have a bad voice coil, or something has shifted and your sub is probably junk.
 

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Put an ohm meter across the + and - of each coil on the subwoofer and it should be ~1.9 Ohms and each coil should be about the same reading. If one reads significantly lower than you may have a short. Check the voltage at the amplifier terminals while the system is playing. The voltage at the amplifier terminal should be about the same reading as whatever you get at the battery terminals but slightly lower is ok. If there is any significant difference like 1 volt than you may have a wiring issue. You can also do a voltage drop test too which is even more accurate by just putting one lead on each end of the wiring connection for both ground and battery cables separately. If you get more than a couple tenths of a volt than you may have a bad connection or poor wiring. You have to do a voltage drop test under load though.
 

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If you have a meter that has a continuity function, pull out the radio harness and meter each wire against a known ground. If one of the speakers is shorted in a door this will show you which one it is.
 

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Discussion Starter #7
If you have a meter that has a continuity function, pull out the radio harness and meter each wire against a known ground. If one of the speakers is shorted in a door this will show you which one it is.
Put an ohm meter across the + and - of each coil on the subwoofer and it should be ~1.9 Ohms and each coil should be about the same reading. If one reads significantly lower than you may have a short. Check the voltage at the amplifier terminals while the system is playing. The voltage at the amplifier terminal should be about the same reading as whatever you get at the battery terminals but slightly lower is ok. If there is any significant difference like 1 volt than you may have a wiring issue. You can also do a voltage drop test too which is even more accurate by just putting one lead on each end of the wiring connection for both ground and battery cables separately. If you get more than a couple tenths of a volt than you may have a bad connection or poor wiring. You have to do a voltage drop test under load though.
Check the wires carefully from the amp to the sub, it sounds like they are shorting out. Make sure that there is no bare copper touching metal, and that the pos and neg wires aren't touching each other. If the wiring is good, the next step is to check the sub. You'll need a multi-meter with an ohm setting to check the resistance, but if you don't have that you can use a battery to see if the cone moves. Take the pos and neg wires from the sub and touch them to the pos and neg of a small 9 volt battery, a AA will work too. If the cone doesn't move at all don't hold the wires to the battery. If the cone doesn't move you have a bad voice coil, or something has shifted and your sub is probably junk.
Thanks for all the suggestions guys. I'm going to hook up the multi meter and see if I can pin point the problem!

Any additional tips/tricks are more than welcome!


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Put an ohm meter across the + and - of each coil on the subwoofer and it should be ~1.9 Ohms and each coil should be about the same reading. If one reads significantly lower than you may have a short. Check the voltage at the amplifier terminals while the system is playing. The voltage at the amplifier terminal should be about the same reading as whatever you get at the battery terminals but slightly lower is ok. If there is any significant difference like 1 volt than you may have a wiring issue. You can also do a voltage drop test too which is even more accurate by just putting one lead on each end of the wiring connection for both ground and battery cables separately. If you get more than a couple tenths of a volt than you may have a bad connection or poor wiring. You have to do a voltage drop test under load though.
Check the wires carefully from the amp to the sub, it sounds like they are shorting out. Make sure that there is no bare copper touching metal, and that the pos and neg wires aren't touching each other. If the wiring is good, the next step is to check the sub. You'll need a multi-meter with an ohm setting to check the resistance, but if you don't have that you can use a battery to see if the cone moves. Take the pos and neg wires from the sub and touch them to the pos and neg of a small 9 volt battery, a AA will work too. If the cone doesn't move at all don't hold the wires to the battery. If the cone doesn't move you have a bad voice coil, or something has shifted and your sub is probably junk.
Ok guys I did a ohm tesst with the sub (inside the box sitting normally) and it's measuring 00.5ohm. is this normal? Or is it because the sub is sitting inside the box?

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Ok guys I did a ohm tesst with the sub (inside the box sitting normally) and it's measuring 00.5ohm. is this normal? Or is it because the sub is sitting inside the box?

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You need to take the sub out of the box. There's a good chance that the wiring inside the box is the problem. And, no 0.5ohm is not good, it's nearly a dead short, and would cause the amp to go into protect, like you're experiencing.
 

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Hey Lenny, 0.5 ohms definitely shows something is up with the wiring of the sub or the sub itself.

If you're in Ontario in the GTA, I can help you with it. Shoot me a PM.
 

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Hey Lenny, 0.5 ohms definitely shows something is up with the wiring of the sub or the sub itself.

If you're in Ontario in the GTA, I can help you with it. Shoot me a PM.
You need to take the sub out of the box. There's a good chance that the wiring inside the box is the problem. And, no 0.5ohm is not good, it's nearly a dead short, and would cause the amp to go into protect, like you're experiencing.
So bad news. Took the sub out and the one coil reads 0.5ohm and the other 0.2ohm. this means the sub is blown/bad now? Can I use the other coil in the mean time?

Thanks JahRah. I'll shoot you a pm now.

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So bad news. Took the sub out and the one coil reads 0.5ohm and the other 0.2ohm. this means the sub is blown/bad now? Can I use the other coil in the mean time?

Thanks JahRah. I'll shoot you a pm now.

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Nope it's toast. Assuming you measured correctly, 0.5 and 0.2 ohms means the sub is done.
 

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Likely the sub has a shorted coil (guessing) because of it overheating and to do that to a Sundown SA series takes a lot because those are tough subwoofers. If you put your nose near the coil do you smell a burnt smell? Does the coil rub if you gently push on the cone. You could always do a recone kit to fix it if you’re up to the challenge.
 

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Likely the sub has a shorted coil (guessing) because of it overheating and to do that to a Sundown SA series takes a lot because those are tough subwoofers. If you put your nose near the coil do you smell a burnt smell? Does the coil rub if you gently push on the cone. You could always do a recone kit to fix it if you’re up to the challenge.
Well I'm an idiot... I had a single coil bridged to the amp and that's what caused it. Yes the sub smells awful I don't even have to put my nose up to it. Looking into replacement options. Live and learn lol.

I'll try that test tonight with the cone.

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O well, we’ve all done some things we don’t want to admit we did at some point but that’s how you learn sometimes. So you basically put the full 800+ watts on one coil and it survived for a little while. Just scrolled to the top and realized you have an SD3 subwoofer and not an SA. The SD3 will not take the abuse an SA will but it sounds awesome when done right. I love mine.
 

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Well I'm an idiot... I had a single coil bridged to the amp and that's what caused it. Yes the sub smells awful I don't even have to put my nose up to it. Looking into replacement options. Live and learn lol.

I'll try that test tonight with the cone.

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There's no need to test any further, if you are getting resistance readings that low. If they sell recone kits for that sub, you can repair it, otherwise you'll want to start shopping.
 
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