Phoenix Gold Phorum

My son just bought an old used zx400ti that is doing something kind of strange. He has it connected to a JL w7, the bass fades in and out. With the volume low it will shut off and then all the sudden it will play for a second and then shut back off. The louder you turn it up the longer it will stay on but even then the bass still fades in and out, it just wont shut completely off. I took it apart and found it was missing one of the 2200uf 16V caps. I replaced the cap and it is doing the same thing. His head unit only provides 1.8 volts through the pre-amp outs. Could this be a problem because this amp requires a higher input voltage. I am going to replace all the caps right now but I doubt this is the problem.

Does any one have any suggestions.

Thanks
Bobby

does the amp turn off or are you saying the signal just drops out?

i wouldnt think the signal voltage would do that. those were built in a time when 1.8v was PLENTY. i have even recently ran them on less.


the part that really throws me is it lasts LONGER on increased volume.


do you have another driver you can test? does the amp behave the same with no load?

heres my initial thoughts. maybe you are running it at too low of a load. when you increase the volume the sub heats up a bit, resistance goes up just enough so the amp can last longer before it goes into protection?

the w7 is a 3ohm sub so maybe its having a hard time with the load?

The signal just drops out. The amp does not go into protect. There are 3 red LED's on the board that come on when it works and shut back off when its not working. I think the LED's should be on all the time but I'm not sure because I'm not familiar with this amp. I have tried the amp in 2 different cars with 2 completely different systems and it does the same thing in both cars.

I just removed the 4 2200uf 50v caps and 2 of them were leaking and were in really bad shape. I am putting the new caps in now and will see how it performs here pretty soon.

Thanks, I will let you know the results in a bit.

if the impedence was too low it might go into protections mode but then it would shut off with more power added to it which is the opposite of what you described.

Try turning the xover pots back and forth several times and try again. I believe the pots can corrode over time and the amp then exhibits similar problems to what you're describing, if I recall correctly.

fuzzysnuggleduck wrote:Try turning the xover pots back and forth several times and try again. I believe the pots can corrode over time and the amp then exhibits similar problems to what you're describing, if I recall correctly.

Thats the first thing I tried, It made no difference.

I finished putting all new caps in and it is still doing the same thing. At this point I don't know what to do. I guess he will have to just get another amp.

make sure the case is not grounded to the chassies of the car it could cause what is happening and also can mess up the amp.

kg1961 wrote:the w7 is a 3ohm sub so maybe its having a hard time with the load?

my wife's car is currently running an 8w7 from a zx400ti and it works very well. i notice little, if any, difference in this subs performance between the zx400ti and the ti600.2

what size sub is connected your son's amp?

12voltjunky wrote:

kg1961 wrote:the w7 is a 3ohm sub so maybe its having a hard time with the load?

my wife's car is currently running an 8w7 from a zx400ti and it works very well. i notice little, if any, difference in this subs performance between the zx400ti and the ti600.2

what size sub is connected your son's amp?

Its a 12" W7

i would reccommend more than 400w for a 12w7, however, it sounds to me like something else is causing the loss of output. try a less power hungry sub if you can just for troubleshooting and check all of your wiring and connections. good luck.

so you never mentioned how the amp reacts to a different driver, or no load at all

Bfowler wrote:so you never mentioned how the amp reacts to a different driver, or no load at all

I connected it to 2 15" audiobahn drivers and it did the same thing. It does not matter if its brideged or stereo. When you say no load at all, do you mean no speakers connected to it at all?

yes, nothing hooked up. i'm just rying to isolate the problem a bit. weather its the amp, or just that load on the amp.

sounds like we already have a good idea what the answer will be though

Bfowler wrote:yes, nothing hooked up. i'm just rying to isolate the problem a bit. weather its the amp, or just that load on the amp.

sounds like we already have a good idea what the answer will be though

It does the same thing I think. Its hard to tell though because with nothing connected to it you can't tell if its working or not.

how hot does it get when it goes down?

ttocs wrote:how hot does it get when it goes down?

It does it from the get go, as soon as you turn it on. It does not have time to get hot.

so even with no music playing on it, it still starts to cook? Sounds like something is going out and causing it to build heat. These have a thermal protection built in, maybe it is tripping that?

Either way if you have tried different subs and it did the same thing, maybe try a different input just for giggles to make sure that there isn't something weird going on with it. Get a headhphone to rca cable and use an mp3 player as a source to confirm that it will stil do the same thing. If it does then you have an amp that is starting to go bad.