Finding a problem with unit power?

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Finding a problem with unit power?

Postby lincolntowncar » 19 Dec 2011, 06:36

On my Ibanez CS9, I am getting a strange sweeping noise...

http://www.youtube.com/watch?v=g9wK05Ha ... aUUv0JCGDD

The first thing I did was test the voltage of my VS One Spot...each of the leads run about 9.35v...The Ibanez DC adapter that I have runs right around 9.03v.

It is obviously something to do with that extra voltage--something the other pedals I have aren't as picky about. The CS9 used to work just fine with the One Spot voltage where it is at which is why it leads me to believe there is a component failure. What could have happened in the pedal? Is it some sort of filter that has failed?

Thanks
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Re: Finding a problem with unit power?

Postby DrNomis » 19 Dec 2011, 11:04

lincolntowncar wrote:On my Ibanez CS9, I am getting a strange sweeping noise...

http://www.youtube.com/watch?v=g9wK05Ha ... aUUv0JCGDD

The first thing I did was test the voltage of my VS One Spot...each of the leads run about 9.35v...The Ibanez DC adapter that I have runs right around 9.03v.

It is obviously something to do with that extra voltage--something the other pedals I have aren't as picky about. The CS9 used to work just fine with the One Spot voltage where it is at which is why it leads me to believe there is a component failure. What could have happened in the pedal? Is it some sort of filter that has failed?

Thanks



Is the Ibanez DC adaptor a Switch-mode type?, if so I think I might know what's causing that strange sweeping noise... :hmmm:


Basically what's happening is that the switching frequency is being superimposed on the DC coming out of the Ibanez DC adaptor, because the frequency is above what humans can hear it is normally un-noticeable, what you are hearing is the switching frequency "Heterodyning" or beating with the sampling frequency (assuming that your chorus pedal is a digital type) and causing sum and difference frequencies, to check if this is in fact the case, try powering your chorus pedal with a 9V battery, and then with a transformer-type 9V DC adaptor, and see if the noise disappears.... :thumbsup
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
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Re: Finding a problem with unit power?

Postby lincolntowncar » 20 Dec 2011, 05:20

The 9v makes the pedal function normally as do the Ibanez 9v DC power supplies that I own. The Ibanez are transformer-type.

The VS One Spot is a switching PSU--here is a clip from their site

Anyhow, the 1 SPOT is a noiseless, high power, switching power supply, like the "switchmode" claims to be. However, "switchmode" is not being truthful about their adapter being transformerless and being able to eliminate 60 cycle hum. All switching power supplies have a small transformer in them, along with some high-tech circuitry. Although it is much different technology than standard adapters, there is technically a transformer in there which is the heart of the adapter.
Regarding the claim of eliminating 60 cycle hum, that's misleading at best. If you have single coil pickups, there is nothing a power supply can do to eliminate 60 cycle hum generated by the pickups. However, any decent 9V adapter (Boss PSA, Ibanez, etc.) has regulated 9VDC output and the voltage regulator in the adapter virtually eliminates "output ripple" in the electrical current which causes noise in most pedals. Good switching power supplies also have very low output ripple, thus eliminating any extra hum in your sound. To contrast, adapters like the Boss ACA, Danelectro DA1, Radioshack, etc., do not have a voltage regulator and will make many pedals hum like crazy despite ridiculous marketing claims like "Zero Hum".


At this point, I am unsure which would be damaged...My chorus pedal used to work fine with the VS power supply. It no longer does...is there something wrong with a filter inside that should eliminate this sound? The VS power supply still works fine with all of my other pedals--including my small clone chorus pedal which is the only other modulation type pedal I have. My MXR distortion+ and other pedals sound the same as they always have.
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