[sdiy] [OT] faulty distortion pedal

[Richie Burnett]

Sounds like a faulty switched-mode power supply to me.  Electrolytic 
capacitor ESR increases at low temperature, and often causes this repeated 
restarting behaviour in old switched-mode power supplies.  So if you don't 
have a replacement to hand, as a last resort you could try putting the PSU 
somewhere warm for half an hour before trying it again! :-)

-Richie,

-----Original Message----- 
From: Michael Zacherl
Sent: Sunday, April 10, 2016 6:20 PM
To: synth-diy diy
Subject: Re: [sdiy] [OT] faulty distortion pedal

Ah, ok thanks! The tempo was like 80bpm … so it takes ~750ms to "charge in 
vain?" ;)
Weird.

On 10.Apr 2016, at 18:59 , Ullrich Peter <Peter.Ullrich at kapsch.net> wrote:

> Hi Michael!
>
> If it is a switched supply then an electrolytic capacitor could cause this 
> failure.
> Search for "elcos" that have broken or rounded tops or if you can see some
> fluid below the elco. (sometimes brown).
> In most cases is smell strange (dog pee smell?!?).
>
> If it only starts for short pulses and then goes out then the startup 
> capacitor
> (normally in the range of 4.7u to 10u) that delivers power for the 
> switching
> regulator for the switch on event could be bad.
>
> Ciao
> Peter
> ________________________________________
> Von: Synth-diy [synth-diy-bounces at dropmix.xs4all.nl]" im Auftrag von 
> "Michael Zacherl [sdiy-mz01 at blauwurf.info]
> Gesendet: Sonntag, 10. April 2016 18:46
> An: synth-diy diy
> Betreff: [sdiy] [OT] faulty distortion pedal
>
> Hi, just had soundcheck for the gig tonight.
> The viola player used a small (probably cheap-ish) distortion pedal,
> which ran off a wall-wart. [1]
> There was an audible pulse, a dull click, in the signal from the pedal.
> Much like from a metronome.
> In fact, before seeing the thing we all told her to switch it off. ;\
> I could see the indicator in the knob going darker with the pulse which
> led me to the thought it might be the PSU.
> The sound was what one not knowing the pedal would expect but she claimed 
> it sounded wrong.
> I think I came across that phenomenon ages ago but alas I can’t remember 
> what it was.
> I can’t say for sure, but I think the PSU was a switched type.
> I didn’t touch it but it looked rather small.
> I ‘just curious’ what could cause this.
> Any thoughts?
> Thanks - Michael.
>
> [1] much like these http://www.thomann.de/gb/movall.html



--
http://mz.klingt.org

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