MXR 70s Script Dyna Comp - Can problem noise be reduced?

Started by tj7, September 21, 2014, 01:08:49 AM

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tj7

Audio:

https://soundcloud.com/matthew-h-slaughter/mxr-dyna-comp

Photos:

http://www.tdpri.com/forum/stomp-box/512456-mxr-70s-script-dyna-comp-can-problem-noise-reduced.html#post6013196

No other pedals in the chain. Telecaster > MXR > Orange AD30. Pedal makes exactly the same noise whether the guitar is hooked up or not. Also makes same noise when buffer is added to the chain (on either side of the MXR).
I have tried different power outlets throughout the house.  It is of course the correct ampage / voltage etc.

I have owned another vintage dyna comp and it did not make anywhere near this much noise...

Any suggestions for what to address would be appreciated - taking it to a tech next week who reckons it might not be something that can be fixed...

Cheers

Ben

craigmillard

Use a battery to eliminate power line noise:)

tj7

Quote from: craigmillard on September 22, 2014, 03:34:13 PM
Use a battery to eliminate power line noise:)

There is no battery option (ie without modification being made) with this version of the pedal.   You would have known that if you had actually looked at the photos I posted.  Sigh.
In over 15 years of using various era FX pedals I have never experienced "power line noise" which emits a sound like this.

Anyone else?  Bueller?  Anyone?

mth5044

Quote from: tj7 on September 25, 2014, 08:52:47 PM
There is no battery option (ie without modification being made) with this version of the pedal.   You would have known that if you had actually looked at the photos I posted.  Sigh.

Harsh.

In fact, you can use a battery without any mods. There are battery snaps to 1/8" adapters that you could use to eliminate the power supply question.

You don't say what kind of supply you are using.

Might also try replacing the transistors and IC as analogmike recommended. The smallbear device will be fine.

tj7

Thanks Matt.
I'm using a standard boss power supply with an adapter to match the plug (TSR) requirement.  It works fine with other pedals (checked).
Yeah, Analogmike has been helfpul, I just bought a couple of those chips from smallbear and will take the lot to my local tech once they arrive.
Hopefully he can sort it out then...
Not keen to go the battery route as I don't like introducing unreliability to my board (ie chance the battery will die when needed)....

mth5044

I agree about the battery. I don't build anything with battery option. BUT in your case you rule out the power supply problem by seeing how it works with a battery. The battery wouldn't be a perminent fix, but just a step in debugging. Power supplies can be fickle, working with some pedals well and not with others.

R.G.

For some reason I can't get the sound. Can you describe it?

Is it more:
(1) hum
(2) hiss
(3) buzz
(4) Grind or growl
(5) put-put-put (motorboating)
or
(6) a more angry sounding hiss than normal thermal noise?

there are different causes for each one of these, sometimes several per category.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

tj7

Quote from: R.G. on September 26, 2014, 12:42:10 PM
For some reason I can't get the sound. Can you describe it?


That's weird... soundcloud is really reliable, the link works on my mac, my work PC *and* my phone...  just checked all three..!

Look, you really need to hear it, my description will be subjective and just won't help.  The link works... keep trying :D