Kicker Impulse IX702 Somewhat Works

[1997eclipsegst]

Hi everyone!

Great site here. Been lurking for a while and finally joined today to ask a question about a amp I have.

It's a Kicker Impulse IX702

The amp will power on and play but the right channel is noisy even with no signal going to the amp. The left channel sounds ok. Also the amp will cut off at low to medium volume. I had it wired up 4 ohm stereo.

The amp has done this since I got it about a month ago.

I took it apart and found numerous cold solder joints and touched them up, but no change.

There is a spot by 2 resistors that looks like it got pretty warm.

I am not sure what to check out on this.

Thanks on advance!

 

[Perry Babin]

What test equipment do you have (multimeter, scope...)?

 

[1997eclipsegst]

Hi Perry,

I only have a digital multimeter. I don't have a scope.

 

[Perry Babin]

Do NOT power the amp up without the transistors tightly clamped to the heatsink.

Does the noise in the right channel ever change when you operate the various pots and switches through their entire ranges?

 

[1997eclipsegst]

Ok. Just put the board back in the chassis and have everything clamped down.

The noise does not change while adjusting the gain, bass, treble pots. But when I switch the 70hz/110hz and full/hp/lp switches it will randomly make the a loud pop thru the right speaker only and puts the amp in protection. After a couple seconds it will come back on.

 

[Perry Babin]

After it pops and comes back on, do you still have the noise in the right channel?

Do you have more than a fraction of a volt of DC on any output pin of any of the op-amps in the preamp section? Place the black probe on one of the non-bridgng speaker terminals.

 

[1997eclipsegst]

Yes the noise comes back when the amp turns back on.

When I tested the output I got:
Left channel: 0.00 vdc
Right channel: -0.04 to -0.06 vdc

I messed around with the crossover and frequency switches to see if which combination causes the pop.

Full to HP - no pop
HP to LP - pop and protection
LP to HP - pop and protection
HP to Full - no pop

In HP and switch 70hz to 110hz and 110hz to 70hz - no pop
In LP and switch 70hz to 110hz and 110hz to 70hz - pop and protection each way

Full - both speakers play
HP with xover on 70hz - both speakers play
HP with xover on 110hz - both speakers play
LP with xover on 70hz - both speakers play
LP with xover on 110hz - only left speaker will play - only get noise from right
Noise is present with any combination above

 

[Perry Babin]

The op-amps are the 8 or 9 pin black ICs on the RCA end of the amp.

 

[1997eclipsegst]

Hi Perry,

Sorry for the late reply. I finally had some time to test IC's today

There is a total of 10

Started with the one at the top of the board by the rca's and worked my way down

1) .01 .01 .00 -8.49 .01 .00 .01 8.55
2) .00 .00 .00 -8.49 .00 .00 .00 8.55
3) .00 .00 .00 -8.50 .00 .00 .00 8.55
4) .02 .02 .02 -8.50 .04 .04 .04 8.55
5) .02 .02 .02 -8.50 .00 -3.22 -3.22 8.55
6) .02 .02 .02 -8.50 .04 .04 .04 8.56
7) .02 .02 .02 -8.51 .01 .00 .00 8.55
8) .03 .04 .04 -8.50 .12 .12 .13 8.56
9) .03 .04 .04 -8.50 .12 .12 .13 8.56
The 10th is by itself to the left of all the rest
10) .01 .01 .01 -8.50 .01 .00 .00 8.56

All are a NJM2068LD part number

 

[Perry Babin]

Assuming that pins 6 and 7 are connected by a trace on the board, op-amp #5 appears to be defective.

 

[1997eclipsegst]

Thanks for the reply Perry,

Pins 6 and 7 are connected by a trace on the board.

I will order a replacement and report back the outcome.

 

[1997eclipsegst]

Hi Perry,

I finally received the replacement op amp and replaced the defective one.

It took care of the amp popping and going into protection when selecting the crossover points and crossover switch.

However it still has the noise present in the right channel. The left channel sounds fine.

Any ideas on what to check next?

Thanks!

 

[Perry Babin]

Did you re-check for DC on the op-amps after replacing the defective one?