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WS 420BT malfuntion


minnmarker

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Hey all.  Any ideas?  On my 420BT only the right channel has sound when "Main" is selected.  I confirmed this by swapping the RCA inputs and the right once again had no sound - so it's not the source.  The funny thing is that with both AUX and Blue Tooth both channels work fine - so its not the amp or connection between the 420 and the amps.

I'll probably wait until Fall to send it back because AUX still works and I can run the XM through that.  Before it goes back for warranty does anyone have any ideas?

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So if you swapped the L and R main inputs and the issue stayed on left chnl output of the EQ, seems to point to an input issue on the L chnl. Output side is good if AUX and BT modes have both chnls output. 

For short term, you can also connect an RCA x 3.5 to your main inputs and connect to the AUX in and use AUX as the main, or BT. 

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That is effectively what I have so I do have music thru the AUX.

I'm not sure I understand your first sentence.  I swapped the input RCAs so the left source RCA (which was just working fine while plugged into the left input) was plugged into the right main input of the 420 - and it did not work.  The problem followed the 420 input jack, not the RCA cables from the source.

I was just looking for possibilities related to the 420 settings or something else easy.  I'll probably live with it for the Summer (use AUX) and send it in next Fall.  Warranty is good until April 2019.

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3 hours ago, minnmarker said:

I confirmed this by swapping the RCA inputs and the right once again had no sound

So you swap the left and right main RCAs and problem stayed on the right chnl of the EQ, correct? If the problem stayed with the right chnl RCA, then the issue is indeed up stream. 

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3 hours ago, MLA said:

So you swap the left and right main RCAs and problem stayed on the right chnl of the EQ, correct? If the problem stayed with the right chnl RCA, then the issue is indeed up stream. 

No it's not. Swapped the input RCAs and the problem stayed on the same side so both RCAs had a signal. Problem is with the 420. The 420 was working last weekend on Main.  Not now, but it is working on AUX so output to amp is good.

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9 minutes ago, minnmarker said:

No it's not. Swapped the input RCAs and the problem stayed on the same side

Then the problem is upstream, if the problem did not stay with the same chnl on the EQ, as you stated, no. 

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It (the problem) did stay on the same EQ channel (same side) despite my switching the inputs - but of course, nothing can ever go wrong with a Wet Sounds device.  I must be absolutely crazy :woot:

It is the 420.  It does appear to be busted.  And no, I am not stupid or a complete idiot.  If all you want to do is promote Wet Sounds and claim they are infallible then don't reply to my posts please.

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20 hours ago, minnmarker said:

Hey all.  Any ideas?  On my 420BT only the right channel has sound when "Main" is selected.  I confirmed this by swapping the RCA inputs and the right once again had no sound - so it's not the source.  The funny thing is that with both AUX and Blue Tooth both channels work fine - so its not the amp or connection between the 420 and the amps.

I'll probably wait until Fall to send it back because AUX still works and I can run the XM through that.  Before it goes back for warranty does anyone have any ideas?

This happened to my WS420 8  years ago.  It was an early model.  Like Generation 1.  In short something when wrong with one of the pre-stage op-amp ICs.  I kept Wetsounds in the loop as I diagnosed it and replaced the IC and resurrected it.  We worked out an equitable arrangement under warranty for a new one.  Just give them a call.  It looked to me that their wasn't good conformal coat on my PCB and that had allowed some corrosion on the IC leads.  But again, Gen 1.

Each of the inputs has an op-amp for adjusting the signal gain into the 420 so that all the sources are matched (if you take the time).  That way you're not playing with volume as you bounce between input sources.  This was the one that went bad on mine.  It's also the most vulnerable to electrical over-stress.  The inputs are high impedance and come right out to the world.  That means any high energy signal like ESD will hit that input like a wave breaking on a bulkhead and splash in the form of high voltage on the pin.  Go high enough and the pin's armor fails and the silicon structure cracks.  If it's well designed and not too energetic it'll do so in a way that lets the rest of the IC keep functioning (if it can without that pin's input).  Op-Amps designed for pre-stage inputs are often designed with extra rugged inputs for this reason.  Combined with proper PCB layout and a list of other things you can have a rugged device.  

Anyways, after that they're pushed through the various op-amps acting as filters for the EQ.

Then they're pushed through the pre-amp op-amp outputs to send the signal down to the amps according to the zone volumes.

ANY of those stages in the signal chain can go bad and have a slightly different cascading symptom.  From what you describe you've got a problem somewhere right at the MAIN op-amps.  Usually the individual chips have two op-amps each.  Sometimes even four.  So L and R are often both implemented on the same chip.  Could be bad solder, ESD, delamination of the conformal coating that allowed the right kind of corrosion, corrosion on the connectors preventing the RCA form make the circuit connection, corrosion on the RCA connector at the board, and on and on.  Silicon rarely just stops working because of wearing out.  Even those economy ST op-amps (full disclosure I'm biased).  It takes external factors to break silicon or break the circuit.  Electro-mechanical parts and electrolytic capacitors are the typical culprits.  After that it's electrical over-stress in all its flavors that is most common.  

Happily you can just reroute and keep using your system for the season.  Which is awesome.

If you're bored you could probably open it up and trace the etch from the connectors in question to the chips they touch and figure out what else might be on that chip.  Odds are if those extra circuits are still working (e.g. Main and Aux appear to be going to the same IC first) then you could speculate the problem is even further upstream and not the chip, but anything from the connector to the pin.

OR I just had a thought.  It could be the Potentiometer used to set the gain of the Main input for matching.  It's also electromechanical and vulnerable to the elements.  It could have corroded enough to basically have changed the output of a perfectly fine circuit from the right signal strength to maximum attenuation as if there's no signal at all.

You could work that pot with a screw driver all the way up and down it's range a few times and see if your signal comes back.  I had an AudioControl EQS that did that on several of the Pots ruining my tune a couple years ago.  I confirmed replacing them fixed it, but didn't bother and just went JL TWK88 after that.

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Thanks @Slurpee

I think I get what you are saying.  I had the main plugged into a non amplified XM Radio output signal so I doubt if I over stressed it so it might have been a random failure.  There was certainly nothing external (moisture or shock) that caused it.  In any case, your solutions are a bit over my head as far as getting them done soon so I'll just wait for the Fall and keep my fingers crossed.

Cheers

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Yup.  You will most probably be fine till the fall.  I can't stop form tinkering with things electronic so don't follow in my footsteps.  Just let Wetsounds help you out.  If it's still under warranty though make sure you don't wait till the fall and past the warranty expiration.

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22 hours ago, Slurpee said:

Each of the inputs has an op-amp for adjusting the signal gain into the 420 so that all the sources are matched (if you take the time).

Where’s is this adjusted? vs the knobs in front used for during song individual adjustments

im making quite a few adjustments for different songs or floating vs riding if I’m playing it loud, loud meaning eq master 45-65%, inboats half, tower 75%, sub 66%.  Are you thinking about the MC1 head unit and it’s capabilities? 

Edited by granddaddy55
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1 hour ago, granddaddy55 said:

Where’s is this adjusted? vs the knobs in front used for during song individual adjustments

You have to take off the cover.  Instructions are in the owners manual.  2 of the 3 have gain adjustments so you can adjust them to match the 3rd.

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  • 5 months later...

So I was SURE I had diagnosed this the right way.  After I pulled the boat I pulled the 420BT out and sent it to Wet Sounds.  They tested it and said it was working normally so they sent it back. I put it back in the boat and, guess what,  it works normally!  So I'm happy and feel a bit foolish. 

Moral: Check your connections 3 times before you declare a component busted.

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