Voodoo Lab

Analog Chorus isn't chorusing
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Author:  kokotele [ Mon Jun 12, 2017 8:37 pm ]
Post subject:  Analog Chorus isn't chorusing

My old Analog Chorus sat in the closet for several years, and now it makes noises like sound effects for tuning an old tube radio. I made a video to show what's going on: https://www.youtube.com/watch?v=FM3U5ib6zCs

The dry signal can be heard at low volume underneath the noise. (There's no guitar playing in the video.)

A visual inspection didn't turn up anything obvious. All the solder joints look good, none of the caps look blown, etc. My intuition says that one of the ICs has gone bad, but I don't know how I'd verify that without replacing one at time until it started working again.

Any help would be much appreciated!

Author:  JohnClark [ Mon Jun 12, 2017 9:05 pm ]
Post subject:  Re: Analog Chorus isn't chorusing

Not really sure what to say about this one. How are you powering it/does it work from a battery? It clearly has been modified at least to add the LED, but were there any other mods done?

Aside from all of that, we would be perfectly willing to check it out for you if you would rather we take a look at it. There would be no charge to at least inspect it. It's possible we wouldn't even charge to fix it unless it needs a lot of work to fix, but we would certainly let you know before proceeding.

I hope that helps!

Author:  kokotele [ Tue Jun 13, 2017 9:22 am ]
Post subject:  Re: Analog Chorus isn't chorusing

John, thanks for the reply.

The only modification was to add the LED, which I did myself. I was powering it from an external power supply, which I also checked and it was putting out 9.2v. Same behavior when on battery power, though.

I think sending it in to you guys is probably the best bet. How do I get it to you?

Author:  JohnClark [ Tue Jun 13, 2017 9:47 am ]
Post subject:  Re: Analog Chorus isn't chorusing

For any repairs please give us a call or write to info@voodoolab.com. Be sure to mention this thread!

Good Luck!

Author:  kokotele [ Tue Jun 13, 2017 7:40 pm ]
Post subject:  Re: Analog Chorus isn't chorusing

I decided to take one last look under the hood before I shipped it off to you, and discovered that it works normally under battery power.

I measured the voltage at the 9v point on the board. 9.25 volts when using the battery, 9.15v when using the power supply.

Any suggestions for things I can look for, or is it still best to send it in?

Author:  JohnClark [ Wed Jun 14, 2017 12:08 pm ]
Post subject:  Re: Analog Chorus isn't chorusing

Could be that the pedal just does not like your power supply... is it a switchmode type supply?

Do you have another power supply that you can test with?

Author:  kokotele [ Thu Jun 15, 2017 11:25 am ]
Post subject:  Re: Analog Chorus isn't chorusing

The power supply is an older OneSpot (original version). It's working fine with other pedals, but I guess this one doesn't like it for some reason.

How much current does the Analog Chorus draw?

Author:  JohnClark [ Thu Jun 15, 2017 11:48 am ]
Post subject:  Re: Analog Chorus isn't chorusing

The Analog Chorus draws less than 30mA. In this case it isn't the current draw but that the Analog Chorus can react funny to some switchmode type power supplies. I am not too sure there is a good fix for this since the source is noise the power supply is generating due to the digital clock frequency it is running at and apparent lack of filtering. Sure, it works for many pedals without noticeable issue, but some pedals just don't like anything but a nice and flat solid DC line... the Analog Chorus being one of the latter unfortunately.

I know a guy that makes great isolated linear power supplies specifically for guitar pedals ;)

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