Boss Chorus "whistle"

[PeterJ]

I have a 2-3 year old Boss CH5 that works great on battery power, but when I plug in a power supply (VS One Spot), it gives off a high-pitched whistle.

The DC jack had a lot of rusty looking corrosion on the sleeve, so I tried cleaning it. When that didn't solve the problem, I replaced it. No difference. Any ideas? Thanks.
Peter

[RDV]

Check this thread.
http://diystompboxes.com/sboxforum/viewtopic.php?t=26138&start=0&postdays=0&postorder=asc&highlight=switching+adapter

RDV

[PeterJ]

Thanks, RDV -- sounds like exactly the problem. Strange how my other pedals aren't affected (even other Boss pedals), just the Chorus.

Peter

[RDV]

Strange how my other pedals aren't affected (even other Boss pedals), just the Chorus.

There's one way to tell. If you know someone with a Boss PSA-120, it's got to work with that one or it's got a real problem.

RDV

[PeterJ]

Good idea, Ricky -- I'll see if I can scare someone up with a PSA-120 or a Danelectro DA-1.
Peter

[phillip]

Good idea, Ricky -- I'll see if I can scare someone up with a PSA-120 or a Danelectro DA-1.
Peter

Lots of pedals (commercial and DIY) really don't like switching power supplies for some reason.  

The PSA-120 and DA-1 are excellent supplies...all my pedals work with either one of them like a charm!  I wish Boss and Dano would make versions of those in 1A versions too.

Phillip

[RDV]

Good idea, Ricky -- I'll see if I can scare someone up with a PSA-120 or a Danelectro DA-1.
Peter

Lots of pedals (commercial and DIY) really don't like switching power supplies for some reason.  

The PSA-120 and DA-1 are excellent supplies...all my pedals work with either one of them like a charm!  I wish Boss and Dano would make versions of those in 1A versions too.

Phillip

You know Phillip, it's really easy to make your own 1amp supply.

RDV

[Paul Perry (Frostwave)]

One reason a switching supply might affect a chorus & not other fx, is if the switcher was ultrasonic in frequency, but generated harmonics with the clock of the delay in the chorus.
I'm not a big fan of switchers, since that one failed from a lightning surge & tried to burn the place down :x

[PeterJ]

What also makes it tough to diagnose is that the chorus is in my effects chain for my banjo, which goes through a DI to the PA, so I can only hear the high-freq whistle clearly at band practice. I can't really hear it through my Blues Jr (that I use for my lap steel) at home. But I'm going to try a non-switching power supply at next Wednesday's practice. I'll let you guys know what happen.

Thanks again for all the help.
Peter

[PeterJ]

Hey -
Just wanted to update everyone who's been so helpful. I tried a DA-1 and a PSA-120 and still have the noise. I've replaced the power jack and reflowed the solder to the in and out jacks. I still get this whistle that goes away when I just run on battery power. Any other suggestions would be most welcome (of course, the easiest answers are: just use batteries or replace the dang thing).

Thanks in advance,
Peter

[Mark Hammer]

I'm curious.  If you stick another cap in parallel with the clock cap in the CH-5 (I assume there is an MN3102 in there somewhere with a small value cap snuggled up against it?) does the whistling frequency change? Does the whistling frequency go up and down at a rate set by the Speed control on the pedal?

If so, is it possible we're hearing heterodyning of the BBD clock and the clocking in the power supply.  Interesting.

It OUGHT to be possible to take that little AC "icing" off the top of the adaptor voltage with some additional RC filtering, shouldn't it?  Or am I way off here?

[puretube]

it is possible to get rid of the sh*t...

the heterodyning with switching PS can happen with BBD circuits,
and with A/D D/A equipped pedals...

I`m wondering, how those (cheap) "electronic transformers" pass the EMI regulation tests...

it`s a PITA, when you`re designing a multiple clocked BBD circuit, powered by a switching PS...  :twisted:  :evil:

[PeterJ]

Thanks for the ideas, guys. I'll have to see if I can squeeze a cap in there (like all Boss boxes, it's pretty tight). I just can't believe this is a design flaw -- wouldn't this have been a problem for lots of folks by now. If you're running into a guitar amp, the "whistle" wouldn't show up. But acoustic players plug into PAs all the time, so you'd think a design flaw would have shown up by now.

Could it be a cap gone bad? I can't see anything that looks like it's leaking, but there are a lot of film caps in there.

'preciate the help, all.
Peter

[puretube]

a cap alone won`t do: put a series-R before the cap...
(and put a small value cap in parallell to the new load-cap).

[PeterJ]

Thanks, all -- I'll mess with these suggestions after my next round of gigs. I'll let you know what happens.
Peter

[MartyMart]

I had the EXACT SAME problem from a new "One Spot" PSU...so.....
Changed it for another back at the shop - DONE !  no more whistle !!

It was bad, new one has been perfect for almost 1 year ...... !:D

Marty.

[Mark Hammer]

Let's just be clear about one thing, though.  Switching regulation of power supplies is a wonderful thing in general.  Its "Achilles heel" however, if I've understood Ton correctly, is that it works best for audio if there are no other clocks in the signal path.  This would suggest that those whose rig consists of a "Hendrix chain" (wah, fuzz, univibe), or something similar, have nothing to fear from a switching PS.  If you have a flanger, chorus, delay line, BBD-based vibrato, or DSP-based effect pedal, there MAY be (and that's MAY, not WILL) be some problems, that CAN be fixed.

Upper-tier techies, please confirm.

[PeterJ]

I had the EXACT SAME problem from a new "One Spot" PSU...so.....
Changed it for another back at the shop - DONE ! no more whistle !!

Interesting, Marty -- probably something to do with the range of acceptable specs. I might look into getting another One Spot.

The whistle only started after I switched from using batteries to using the One Spot. But since I'm still having the whistle problem with a Danalectro DA-1, it looks like it has to be something in the pedal itself.

Peter

(edited for typo)

[puretube]

just came across this thread:
http://diystompboxes.com/sboxforum/viewtopic.php?t=33670

a third candidate for producing heteroes...