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Dr Zeus 20th January 2011 09:40 PM

Kicker ZX2500.1
This amp powers but does not play. The test speaker presents the pretty standard Class-D low amplitude white-noise but nothing more.

The amp is in great shape and has never been opened. There are no burned components inside to speak of.

The rail voltage is +-62vDC referencing general ground.

The opAmps on the pre-driver board 9Left of photo) all measure +-12vDC on the power pins referencing amp general ground.

After a few minutes, vertical driver boards get warm but touchable.

I tried swiveling the gain pots and controls to no avail. The quiet sound of the sea out of the test speaker does not change.

I'm about to take it fully appart, but past experience with this type of thing tells me it might be simpler than something hidden under the PCB.

Resistence on RCA shields is 40k just about everything on the board including speaker terminal outs and amp ground. Im not sure where secondary center tap would be on this amp.

Why wont this amp make sound?

Dr Zeus 20th January 2011 09:50 PM

Exploring more with the RS Miniamp, I find that some of the opAmps have sound on the input and output pins, and some do not.

Dr Zeus 20th January 2011 10:17 PM

WOW this is a big amp. Possibly one of the most costly I've repaired as well. Kicker MSRPs this bad boy for ~$1,400. Its Class D Monoblock, 2500x1 at 2 ohms. WOOW.

This amp has 20x IRF3205 transistors 12x IRF640, and 20x IRF9640.

I need to get this thing fixed lol!

I pulled the board out of the sync. Darn; no signs of trace damage...

Perry Babin 20th January 2011 10:21 PM

Do you have clean audio on the output pin of the preamp board?

Dr Zeus 21st January 2011 12:59 AM

I'm not exactly sure which one of these pins transmits the audio to the main PCB. The 9 pins are labled as pictured. Starting fro mthe bottom which appears to be Pin1 - REMBAS - I measure the following DC voltages referencing amp general ground:

Pre-Amp board pins:
Pin 1: 10.51 labeled REMBAS
Pin 2: 0.005 labeled GNDS
Pin 3: -11.75 labeled -12v
Pin 4: 12.00 labeled +12v
Pin 5: 0.005 labeled GNDP
Pin 6: 13.36 labeled +BATT
Pin 7: 13.41 labeled REMOTE
Pin 8: -19.84 labeled MUTE
Pin 9: -10.61 labeled SUB_IN

Dr Zeus 21st January 2011 01:10 AM

Q101 and Q102 are measuring 50 ohms from legs 1-2. They are M09 transistors, or PMBFJ309.


Pin 1 is source, Pin 2 is drain.

Are these bad perhaps or are they muting circuitry?

Dr Zeus 21st January 2011 01:47 AM


Do you have clean audio on the output pin of the preamp board?
I think I found a good center-tap reference. From there, I find audio signal comming off most of the opAmp outputs on the pre-amp board. There is no audio on any of the pre-amp's pins leading to the primary pcb.

Here is where I'm thinking secondary center tap is on this amp. its ~2ohms to general ground.

Perry Babin 21st January 2011 02:12 AM

That's normal for those transistors.

The secondary CT is the same as for most amps.

Do any of the op-amps on the preamp board have significant DC on their output pins?

Dr Zeus 22nd January 2011 05:19 AM

U107 has -10vDC on all pins except but pin 8, which has +12

U106 has +-12vDC on the power pins, and -10vDC on pins 6 and 7.

The other opAmps have ~0vDC on all output pins

Perry Babin 22nd January 2011 05:26 AM

U107 appears to be defective. I'm assuming that it's an op-amp.

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