I've been doing car audio awhile..and I've never burnt something up untill tonight.
It was my old Kenwood tape deck(in my Nova, the car is all original..except for the tape deck). I had a system running off of it for about 3 moths. Well, I tooke out that system, replaced it with a system I had just bought. A single 12" and a 850w amp. I ran that stuff all day, then, later that night took out the box to check it and see if all the screws were tight. When I hook the box back up to the amp..the protection light came on and the sub wouldn't play..but the radio was working. So, I turned off the car and turn it back on. I went back to the amp and the sub still wouldn't play, but, I saw a small spark come from the Ground hook up on the amp...THen, my amp went dead..and it smelled like burning plastic, and mow my radio wont come on.

Heres my questions:
1. What did I do wrong? I know how to wire this stuff..and it was all wired right.
2. Do you think it took the amp along with the radio? I hope not man..The amp was expensive.

 

If your amp comitted suicide (or was murdered), it could have sent 12 volts right up your RCAs, which would cook the outputs on the deck. When my kicker amp croaked it took my head unit with it.

 

That's how.
If there was a spark there was a bad connection. A bad ground at the amp CAN kill the HU. What happens is the amps power ground and RCA input ground are "the same", so are the HUs power ground and RCA output ground. When you have a bad ground connection at the amp the amp will try to ground through the shielding of the RCA cables to the HU though the HU on a vary small ground trace to HUs ground wire. And no part of that path can handle the current the amp needs.
Now, how bad is the damage? May not be that bad or could be fatal. You'll need to do some trouble shooting.
The HU first, Check the fuse in the back of the radio and the car's fuse box. Get a DMM/VOM and check for B+ (12Vdc) on the HU's red and yellow wires. Check continuity to ground on the ground (black) wire. With those three things the HU should power up. If not,,,,, well,,,,,, that would be bad. If it does, there still could be damage to the HU. Are the speaker outputs working? If not that's a bad amp IC or ground to the amp IC. Also check the grounds at the RCA outputs and to the case of the HU. Check for continuity between all three points (RCA ground, power ground wire, and case).
Now, on to the amp. UN-PLUG the RCA cables. Next, go back over your power connections. If there was a spark on the ground terminal, there's probably some carbon there now, clean it off. Grab the DMM/VOM And check for B+ (12Vdc) On the B+ terminal and REM. terminal and check the ground with the DMM/VOM. With those three things the amp should power up. Did it?

 

There's all most no way the amp can send 12V "up the RCAs". Usual the problem is the ground. Which can leave you with some stray voltage On the RCAs from the voltage drop on the ground, but shouldn't be a lot. I Have seen a couple older Kicker amps with VARY bad solder connections at the Power terminal block. A bad ground here would have the same effect. If i remember right you're an engineer, did you try to fix either the amp or the HU? What did you find? I just like keeping track of how things break.

 

Tell that to my Kenwood head unit. The early Kicker ZR amps had a very well known tendancy to cook transistors (I assume power supply transistors, not output transistors), and when that happened, I believe it caused a direct short between the power line and the signal line.

When this happened, I never opened up the equipment. Both were virtually brand new and I sent them in for warranty work. But... this happened with a LOT of the early ZR amps, so it was a fairly well known problem.

 

what did type of output did your amp have once it "Cooked"

my ZR1000 recently bit the dust, and i want to get it repaired, but nobody i have found wants to work on it.

 

It would be nice if it was that easy some times. "No, you can't break like that, it doesn't happen."
I don't remember what the ZRs PCB looked like (that's all I ever remember of units) and lost any access to service manuals for Kicker. But if I remember right, and going off the odds, I would think it would have been the switching FETs in the power supply. Probably 95% of amp failures are switching FETs or output transistors, always has been. It's vary common to see switching FETs fail and take out a ground trace with them before the fuse can let go. When this happens it's the prefect set up for what i described.
Again, if I remember right and going off the odds for this part. But that amp (and 99% of quality amps) has an input stage made up of not much more then a resistor, a de-coupling cap, and an isolation amp. Just an op-amp with a gain of 1:1 to 1:3. The op-amp will use ether +10 to +18 or +,-9 to +,-15. All of this is derived from the power supply. For the amp to have "sent 12 volts right up your RCAs” the power supply would have to be running (can’t with shorted FETs) AND that op-amp would have to go shorted internally B+ to the input (I can’t see this being likely) AND the de-coupling cap would have to be shorted (this can happen). There’s just no other path for DC to get on the RCAs.
Did you measure the 12Vdc on the RCA inputs? If I have this all wrong I’d like to look into what is going on IN the amp that could cause this to happen.

Onebadwagon, Are you seeing 12Vdc on the RCA input? Like I said, if this is happening I’d like to look into it farther. Do you have DC on the outputs? Like I said, I don’t have access to Kicker service manuals any more, but I can walk you though some of the easy things to check. What’s it doing?

 

I never opened up the amp and tested the failure, so I can only go by what I was told by the other techs, but I have had situations in labs where I've managed to burn up various FETs and op amps, and in the process, cause an internal short between pins. I guess it's possible that the "12" volts was actually whatever the rail voltage on the Op-amp or FET was, and shorted to the signal pin. But again, no sense in arguing, because I didn't open it up to check for myself. I just sent it back and let the good folks at Kicker deal with it.

 

last time i went had it hooked up, it was humming out the speaker outputs, and then it blew one of the smaller transistors.
when it did, there was an audible noise from the amplifier itself, now disconnected from speakers.


adam

 

Well, this had to be one of the 10%. I was hopping for DC on the outputs, this an easy output transistor fix. With no service info on this It going to be hard.
1. Was this smaller transistor attached to the heat sink itself?
2. Was the noise "from the amp itself" a humming noise?
3. Was the humming from the speakers vary loud, like full volume?
4. Do you know or can you tell if the "smaller" transistor is in the power supply stage or the pre-amp stage?

 

yes, the humming from the speakers was very loud like full volume, yes, it was a slight humming noise from the amp itself, that i did not notice until i was bench testing it.
it is labeled Q13 ( i realize that does nothing for you)
it is the 7th relay from the power inputs on the same side of the board as them.

yes, the transistor is one of them that is sandwiched to the heatsink.


adam

 

Lets see if we can ID the circuit. I don't think I've worked on a ZR1000 before, but I have been into the smaller ZR amps.
If you look at all of the transistors affixed to the heat sink you should be able to see THREE "patterns" to how there're placed.
TWO of these patterns should be VARY similar, usaly one on one side of the amp and one on the other. These would be the two channels of the amp.
Then there well be ONE that is different (all the rest of the transistors), usaly to the end of the board (both sides) closest to the power connectors. There should also be a transformer (big Donut-O-Wire) or two hanging out nearby. The transformer is the easiest thing to spot. This would be the power supply.
I tried to track down some service manuals but no luck. Lost the ones I had in a move. If i still had them the Q13 would be VARY helpful. It sounds like it MAY be an output transistor failure from the description. The buzzing form the amp is probably being made by the transformer. They'll do that when there is a high load on the power supply, like trying to dump power into a shorted output.
Some things I should have put out there first.
You have to under stand that there is a small chance that the parts you replaced may burn right back up IF there is a bias problem. Unfortunately there is no real way to test for this in most cases other then the smoke test (give it power and see if it smokes). This sounds vary unprofessional but it's just the way it goes. Car amps use my two least favorite circuits to troubleshot. Switch mode power supples and direct-coupled amps. They can be a PITA because in some cases you have to trubleshot them cold/dead chasses (no power) or they crap righ back out.
Do you know how to test a transistor? If not I don't know how far we can go on this?

 

Just by reading your posts on this thread I can tell you know alot about electronics, but I can also say that my brother fried his preouts of his deck when his amp's ground came loose. When the ground was disconnected, the 12V searched for the path of least resistance and unfortunately the RCAs were it. Once you put a few amps into some of those lower powered trannies and those ICs (2n5088, 2n3904, JRC4558s, TL072s, etc) you are going to cause internal shorts.