Alpha Juno 2 VERY noisy chorus needs repair help - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th November 2010, 02:06 PM   #1
diyAudio Member
 
Join Date: Nov 2010
Default Alpha Juno 2 VERY noisy chorus needs repair help

Recently i bought this unit cheap knowing a few things needed repairing (skippy dial fixed by resetting the synth, uneven velocity fixed by cleaning, presumably weak battery but works ok) .
All of them fixed easy but I created a new one:
A noisy chorus circuit!

The noise can be described as digital noise/silence shaped with a square wave 50% / 50% timeframe (drrrrrt / silence / drrrrt / silence...). The noise increases with CSR RATE, but goes away if bellow ca 70 value.
If I sett CSR RATE value low, play a note and increase CSR RATE it plays correctly. But if i play a new note with the now high setting it will distort the sound.

VCF and VCA LFO is not touched by this error.

The unit is fairly clean and shows no obvious signs of shorts or defect parts.

Any help here?

I have the 20 page service manual available if requested.
  Reply With Quote
Old 24th November 2010, 04:07 PM   #2
diyAudio Member
 
gain wire's Avatar
 
Join Date: Nov 2004
Location: NCR
hi there trondl,
my initial response was going to be check the connections, clean the potentiometers, but I see you've already done that.
I am starting to wonder if maybe it's a capacitor problem, an old electrolytic might be leaky, something like that.

You know what? post this on Gearslutz.com in the geekslutz forum. I think you'll have a good time there and better luck.

cheers,

gain-wire
__________________
Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig
  Reply With Quote
Old 24th November 2010, 06:37 PM   #3
diyAudio Member
 
Join Date: Nov 2010
thanks gain-wire.
now posted on gearslutz
  Reply With Quote
Old 25th November 2010, 08:44 AM   #4
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
If the chorus is adding this, get the scope on it. Chorus is generated in a variety of ways, but it involved phase shifting. SO if there is a bad stage in a bucket brogadee, or whatever, it should be visible. What does this distortion look like on a screen?
  Reply With Quote
Old 25th November 2010, 01:39 PM   #5
diyAudio Member
 
Join Date: Nov 2010
Don't have access to a scope but this is how it sounds on CSR RATE: 127 and dropping towards 0 value after 5 seconds. Note that this is recorded at very high volume and is not very audible when played at normal levels.
Attached Files
File Type: zip ju2 chorus noise csr rate 128-0.zip (274.6 KB, 3 views)
  Reply With Quote
Old 10th December 2010, 03:00 AM   #6
diyAudio Member
 
Peckerwood's Avatar
 
Join Date: Oct 2010
Location: Texas
Have you ever heard any effect that was NOT noisy? By noisy I mean compared to having nothing between the instrument and the amp. If you have I would like to buy it.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Arcam Alpha CD Player noisy traffo help AndrewGM Digital Source 6 4th December 2009 10:48 PM
roland jazz chorus-55 amp repair weesatron Solid State 3 21st May 2009 09:01 AM
Looking for service manual for Alpha Juno 2 Bitrex Instruments and Amps 1 18th April 2009 09:17 AM
Noisy spinning disc in Arcam Alpha 7se CDP anb Digital Source 3 10th December 2006 09:22 AM
Roland 'alpha juno '1' tuneman Instruments and Amps 2 15th November 2005 02:26 AM


New To Site? Need Help?

All times are GMT. The time now is 07:54 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2