Kicker ZR1000. Blown Power Supply.

arthur8

Member
2012-04-04 11:55 pm
Hi.

I would like to first thanks Perry* and everyone from this forum, i already repaired a lot of the old Rockford Fosgate's and some old Orion's just reading from this forum topics. I have a hosting company, anything that i can help to keep this project alive, let me know.

Well... let's go for the problem on my Kicker ZR1000.

Today, after giving a 'demo' for a friend with ~20 minutes of decaf hip hop (the musics are 99% sine waves) and the magic smoke appeared.

From what i can see, the power supply for ONE channel is blown.

Some bad things was done to this amp:

1. My stereo RCA cable started to have a bad contact on one channel and i removed the stereo RCA cable from the channel L. So, the amp was working on just the R channel, i don't know if there is any problem with this, since i was running the amp to a bridge. I did this about three weeks ago.

2. This amp was pushing a 2 Ohm rockford fosgate T2, half the rated 4 Ohm for this amp, in bridge. This was done about 2 years ago and the amp survived until today. EDIT: Looks like it can run @ 2 Ohm as the manual: http://prntscr.com/b6k23q

3. When i bought it, i seen that the first FET from the power supply that is now blowed was already replaced. But it was working, so i did not worry about this.

4. Protection LED did not lighted up. Power LED is turning on when we turn on the AMP. There is no Audio on Channel 1 or 2, the bridge is off course without audio too.

Some important details:

1. This amp had the recommended 150A fuse connected to the +B.

2. This amp is powered by three 65A batteries and a 160A batteries. Not seen any undervoltage.

I really would like to fix it, and avoid it burning again.

The power supply have 4 rfg70n06, looks like three of them are blow. The one the old owner changed looks good. Can you recommend me any replacement for this FET's?

It is possible to put more powerful FET's on this power supply, to make the amplifier more solid than already it is?

Thanks!
 
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I would suggest the cause of failure is the 2 ohm load on a 4 ohm bridged output.
You were probably just lucky it lasted as long as it did.

You don't need more powerful mosfets in the supply just run it as it was intended.
If you put in more powerfull mosfets then all that will happen is the next link in the chain will blow (output mosfets)

If you need a more power buy a bigger amp.
 

arthur8

Member
2012-04-04 11:55 pm
I would suggest the cause of failure is the 2 ohm load on a 4 ohm bridged output.
You were probably just lucky it lasted as long as it did.

You don't need more powerful mosfets in the supply just run it as it was intended.
If you put in more powerfull mosfets then all that will happen is the next link in the chain will blow (output mosfets)

If you need a more power buy a bigger amp.

My mistake. I have so many of this old kids that i forgot the specs of this one.

Looks like this amp can run at 2 Ohm: Screenshot by Lightshot (taken from the PDF manual).
 

arthur8

Member
2012-04-04 11:55 pm
Here is an image of the FET's. The 4th one have been changed by the old owner. Exact same model but is showing "h9918" and the other three FETs (originals) shows "h9714".

Maybe this difference created the problem? From what i learned, we should change all the FETs when one of them blow up.

img
 

arthur8

Member
2012-04-04 11:55 pm
Well.

Before i get some help here, i decided to replace the blown FET's. I found on my city the 70NF06 (TO 220 Package) very cheap, so i bought 4 to test it out.

The amp powers up normally and there is an 5A consumption. I did not tested if there is any audio afraid of a VERY strange noise coming from the power supply, near the big *** toroid.

Really sounds like a capacitor venting. I don't know if this noise came from the toroid or from some bad capacitor. I just turn it on, and starts the noise, i turn it off and the noise go away instantly.

Suggestions?
 
If the original FETs are available, I'd use them. This amp has no power supply driver transistors. All work is done by the driver IC. FETs that are rated for more current may be a heavier load and could make the amp unreliable. You probably could go to a different FET but going with the original is guaranteed to work.

A venting capacitor is generally accompanied with a nice cloud of steam/smoke.

5A is a bit high but that could be due to higher than normal biasing of the output stage.

Can you touch the windings on the transformer and make the noise change? I had one of these with shorted windings.

Sometimes insufficiently damped regulator circuits (regulator circuits that react very quickly - too quickly) can make the transformers produce noise. If you have a 12v power supply that has voltage control, lower the voltage to about 11v to see if that changes anything.
 

arthur8

Member
2012-04-04 11:55 pm
Perry,

I see it.

Thanks for the advise.

I just turned the amp on (even with the big noise from the toroid) and i can hear audio now.

I'm using three 7A batteries as a power supply, and i think it's because that when i increase the volume, the amp enter in protection mode. But looks like both channels reproduce a clean audio.

I will now order some of this FET's and let you guys know if this will work or no.

Can you give me some tips about this toroid making this noise? This never happened before.
 

arthur8

Member
2012-04-04 11:55 pm
Hey Guys,

Well, looks like the amp is working again. The amp is pushing about 5-6A without load.

But, i still have a problem on the toroid itself. I get a very strong noise from it.

Maybe it is a transformer leakage? Maybe is some winding vibrating? Never had this issue with this amp on years of heavy usage.

I will make and upload a video later. :(