Low Dry & Wet Output Problem

Moderators: George Geddes, David Martin, dave robinson, Iain Purdon, ecca

Low Dry & Wet Output Problem

Postby Kiwi » Fri May 17, 2013 4:47 am

Greetings everyone,

My Low/Dry output is very low (faint) even when the FET level control is at maximum. The wet output works fine. I removed the daughter board and used a dual jumper as explained in Piet's build instructions to test it as guitar preamp and the result is the same. I checked the IC voltages again as per Piet's instructions and they measure correctly. Being non technical I am not sure what else to check apart for bad wiring connections from the board to the dry/wet output which I have done. To be honest the problem has happened before and usually went away after I plugged the output cable from the unit into the guitar into the wet output and then back into the dry/wet output. To check for a faulty output socket I swapped the output wiring over to the change the sockets and the problem went with the swap. i.e the dry/wet output was still very low so the socket is not fault. Any suggestions would be great. Cheers, John
Kiwi
 

Re: Low Dry & Wet Output Problem

Postby ecca » Fri May 17, 2013 7:08 am

John, try swapping the op-amps around.
The dry/wet outputs are from different ICs.
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Re: Low Dry & Wet Output Problem

Postby Kiwi » Fri May 17, 2013 7:43 am

Hi Ecca, I did the swap but sadly still the same result but thanks for the idea. I was quietly optimistic that it would work. Regards, John
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Re: Low Dry & Wet Output Problem

Postby ecca » Fri May 17, 2013 8:16 am

Have you checked components, are they the right parts in the right place ?
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Re: Low Dry & Wet Output Problem

Postby Kiwi » Fri May 17, 2013 9:35 am

OK Components checked out. It looks like an intermittent connection somewhere as when I disconnected the unit from the case and gave the motherboard a slight wiggle the sound came through for a moment so I will concentrate on this. It will be a bu..gg ..er if I have to replace the motherboard and rebuilt it. Oh well keeps the brain ticking over. Thanks for you help so far. You are pretty awesome with the support you provide. Cheers, John
Kiwi
 

Re: Low Dry & Wet Output Problem

Postby bazmusicman » Fri May 17, 2013 11:58 am

Hi John,

I had the same problem with the WET side of my unit. When I wiggled Capacitor C14 the Wet sound worked, so I resoldered the conection and its been fine.

Now Capacitor C14 might not be your problem (i.e. the Dry side) but its worth giving the components a small wiggle with the unit switched to the Dry output, this may then show up any dry ( no pun intended!) joints.

Best Regards,
Baz.
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Re: Low Dry & Wet Output Problem

Postby scmitche » Fri May 17, 2013 7:19 pm

Hi John,
Have a look at the soldering of these components around the Left (mix) channel output op-amp IC1a:

Start with the output resistor R27 - 1k, then output capacitor C4 - 1uF, then main feedback resistor R5 - 10k, then input resistor to input of op-amp R8 - 10k.

The rest of the components around IC1a merely adjust the frequency response so if the main components above are soldered in correctly and each main component is functional there should then be a mixed output.

Hope this helps.

Good luck,
Steve
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Re: Low Dry & Wet Output Problem

Postby scmitche » Fri May 17, 2013 7:29 pm

Hi John,
Just had another thought. Did you use screened cable for the input and output connections to/from the eTap2hw? If so, did you check for a tiny short from the many screen braid wires to the main core, it's so easy to miss one of the tiny braid wires creating a short. I purchased a magnifying glass for having a good look at things like that and also for looking at the soldered joints on the board. You should also see this by checking for a short to ground by using a digital multi-meter at input and output sockets and from level potentiometer wiper to the board.

Regards,
Steve
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Re: Low Dry & Wet Output Problem

Postby Kiwi » Sat May 18, 2013 9:52 am

Thanks Baz & Steve,

Well the problem was with R8 which Steve suggested I should check. I have re-soldered it and the unit is working normally again. Thanks guys for your input along with Ecca it was very appreciated. It is awesome that we get such great support on the forum. OK so I have learnt a few new things through this problem but I am happy to take off my techo hat and get back to the music :lol: Regards, John
Kiwi
 


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