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Re: Fender Ultimate Chorus Problem ......listen to audio file

Started by teemuk, November 20, 2007, 02:10:40 PM

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teemuk

"Problems that change gradually - usually they decrease or disappear - as the equipment warms up are often due to dried up electrolytic capacitors."
- http://www.repairfaq.org/sam/tshoot.htm#tshsqt

Ity may also be an issue of intermittant signal path. Or a combination of both.

http://www.fender.com/support/amp_schematics/pdfs/Ultimate_Chorus_Schematic.pdf

kozmo

I have an ultimate chorus, when I turn it on it plays fine but after it warms up I start to hear a crackling sound when I pluck the strings. I've checked speakers-ok, it's not the guitar-new,plus It does the same thing with another guitar. It only does this AFTER it has warmed up, usually about 5-10 minutes after powering up. Any idea guys? The first two audio files are with my guitar, the third audio file is with my ipod hooked up through the amp.

http://youtube.com/watch?v=tipKqO_bkig

http://youtube.com/watch?v=iyTTFtGNaBE

http://youtube.com/watch?v=Q_ZI069rXnQ

nashvillebill

Troubleshooting an amp long-distance isn't very easy, but I will attempt to help.

It sounds like you have a "hum" coming through the amp, even when you're not playing (or is that just a quirk of the recording process?)

If it's a hum-especially a hum all the time, once it starts--, this is likely to be an easy fix.  I have seen many posts on the 'net that the Ultimate Chorus didn't adequately secure the filter capacitors--that's the 2 big things that look kinda like flashlight batteries.  The vibrations of playing and transporting the amp would eventually cause the solder connection to break free, and the result would be a hum all the time.  I've seen a UC at the local used music store that had this same condition.  All it needs--if this is the case--is to resolder the connections, and then use a hot-glue gun to put a big glob of glue around the caps to hold them in place better.

However, if there isn't a hum, then there's a couple more possibilities.  A fried speaker (distorted voice coil) will cause a noise like that when you play, but I think it would do it all the time.  Another possibility is an op-amp that's going out, I believe there's about 8 or 9 TL072 op-amps all through the amp.

Here's a way to track down the problem further if the hum doesn't occur all the time.  First, does it do it through a set of headphones?  If so, that eliminates the speakers as a problem.  Also likely eliminates the power amp section.  Another test, your amp has a MONO SEND and a MONO RETURN.  Use the Mono Send to go to another amp, or even a tape recorder, just anything else.  Do you hear the buzz in the other amp or on tape?  If so, it's in the preamp section of the Ultimate Chorus, maybe one of your effects fried the first gain stage.

Post and let us know.  By looking at the amp as a series of separate components--preamp, power amp, speakers, and using the knowledge of the signal path, you can pinpoint the problem a little better.

joecool85

Quote from: nashvillebill on November 20, 2007, 07:22:17 PM
Troubleshooting an amp long-distance isn't very easy, but I will attempt to help.

It sounds like you have a "hum" coming through the amp, even when you're not playing (or is that just a quirk of the recording process?)

If it's a hum-especially a hum all the time, once it starts--, this is likely to be an easy fix.  I have seen many posts on the 'net that the Ultimate Chorus didn't adequately secure the filter capacitors--that's the 2 big things that look kinda like flashlight batteries.  The vibrations of playing and transporting the amp would eventually cause the solder connection to break free, and the result would be a hum all the time.  I've seen a UC at the local used music store that had this same condition.  All it needs--if this is the case--is to resolder the connections, and then use a hot-glue gun to put a big glob of glue around the caps to hold them in place better.

However, if there isn't a hum, then there's a couple more possibilities.  A fried speaker (distorted voice coil) will cause a noise like that when you play, but I think it would do it all the time.  Another possibility is an op-amp that's going out, I believe there's about 8 or 9 TL072 op-amps all through the amp.

Here's a way to track down the problem further if the hum doesn't occur all the time.  First, does it do it through a set of headphones?  If so, that eliminates the speakers as a problem.  Also likely eliminates the power amp section.  Another test, your amp has a MONO SEND and a MONO RETURN.  Use the Mono Send to go to another amp, or even a tape recorder, just anything else.  Do you hear the buzz in the other amp or on tape?  If so, it's in the preamp section of the Ultimate Chorus, maybe one of your effects fried the first gain stage.

Post and let us know.  By looking at the amp as a series of separate components--preamp, power amp, speakers, and using the knowledge of the signal path, you can pinpoint the problem a little better.

I would resolder all connections on the board, it sounds like a loose solder could be the problem.  Make sure to drain the power caps first or you may get an ugly zap/short something on your board.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

kozmo

Last night I hooked up headphones to it (no speakers) and still got the same sound. It started making this sound a couple of days ago after it warmed up, but now it does it when I turn it on and does it all the time now.  If I take it to a tech, should I take the whole amp (case and all) or should I just take what you see in the picture (board and panel)? By the way I'm new to this board and I really appreciate everyones imput!!!

joecool85

I would take everything in to the tech if you decide to go that route.  However, keep in mind that it will be pretty expensive.  Guitar amp techs don't work cheap.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

kozmo

Yea, I think that's what I'm going to do.  Thanks to everyone!