# Alpine 3342 EQ Repair - No Sound



## cameronbprince (Jan 21, 2014)

Are any Alpine techs on this site that have any experience repairing the 3342? It powers up, all controls seem to work properly, but there's no sound from either the front or rear outputs. When in the spectrum analyzer mode, the 31.5 and 63Hz bands are pegged and the others flutter, even with no input (see photo).

I tested each pin of the DIN cable for continuity. I also did a quick inspection inside the controller and the brain. The only odd thing I found was chunk of styrofoam in between the sandwiched boards, which appears to be a wedge that keeps another small outboard PCB (wrapped in heat-shrink) in place. None of the caps appear leaky and there are no signs of previous repair.

This unit does have a DC-DC switching supply and I'm wondering if it might be the culprit.

If anyone has any suggestions please let me know. Service and owner's manuals would be awesome too.

Thanks,
Cameron


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## ATOMICTECH62 (Jan 24, 2009)

Check to see if the power supply is producing +/-15 or 12 volts.Could also be the processor chip.


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## cameronbprince (Jan 21, 2014)

Thanks for your reply. Going to pick up my scope at the storage unit later tonight to check for voltage and waveform. Will let you know.


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## cameronbprince (Jan 21, 2014)

I broke down and purchased the service manual PDF. A check of the test points shown in the excerpt of the manual I've attached show that there is no negative voltage present. The DC-DC converter isn't working. I further confirmed this with my scope, which shows no waveform on the transformer. This led me to check Q801, Q803, Q807 and Q808. I found that 801 is good, 803 is weak and the other two are shorted. Looks like it's time for a Digikey order.


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## mosconiac (Nov 12, 2009)

Good luck. That bad boy needs to live again. I used to lust over those when I was in college...and broke.


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## Jason B (Jul 6, 2010)

Awesome EQ. I still have mine and use it!










Did you get it fixed?


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## cameronbprince (Jan 21, 2014)

Yes. Three transistors had went bad. Worked like new once I replaced them. I played with it for awhile and sold it. I decided I liked the LEDs in the 3337 better than the LCD.


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## Jason B (Jul 6, 2010)

Cool. So, are you addicted to the sound that comes out of this EQ too? I'm afraid to upgrade to a newer head unit with no EQ in fear it's just not going to sound the same.


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## cameronbprince (Jan 21, 2014)

Well, I actually use an MS-8 in my truck. The 3337 is in my car audio collection here on a bookshelf near my desk.


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## Jason B (Jul 6, 2010)

cameronbprince said:


> Yes. Three transistors had went bad. Worked like new once I replaced them. I played with it for awhile and sold it.


Ok, well, I have my car in for repairs, got it back and no sound from the 3442. I'm assuming this is coincidence, but I'm pretty bumped. I checked everything, and it's def the EQ that's not letting any sound through. I don't have any contacts or really trust anyone around here to look at it. What are the chances I can send it to you to take a look?

I did take it apart for fun it does have a but of a burnt smell, but can't really see anything by looking at it.


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## Jason B (Jul 6, 2010)

Alpine 7982 and alpine 3342 EQ. My EQ just broke, and no sound, Something in the brain box. ANy ideas?


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