Fender Ultimate Chorus with broken chorus

[Notafraid]

I just bought a Fender Ultimate Chorus. It is about 12 or 13 years old. Everything works fine on it except for the chorus. The little light that blinks on the front panel indicating the depth and rate of the chorus blinks on and of at the proper rate, and changes colors when the depth and rate pots are turned, but it makes no difference to the sound.

I had a few dirty pots when I got it, and I got a look at the top of the board. Nothing obviously smoked on it, but I haven’t looked at the bottom of the board. I have some electronics knowledge, had a few classes, and built a few things, but I don’t know how to use a scope. I have got a meter, and could make some repairs if I knew what I needed to do.

Anyway, any help or advice would be appreciated.

[Mark Black]

I think those are true stereo output and use only one of the speakers for the delay/chorus effect, leaving the other as dry signal only. So if one of the speakers is bad or disconnected the chorus effect might be non-existant. Try unplugging first one then the other to see if you still get any sound at all. According to the schematic (available at: http://www.fender.com/support/amplifier_schematics.php) it looks like the right speaker is in charge of the chorus effect.

Also the stereo effects loop contains complex normalling switching in the send & return jacks which could have dirty/oxidized contacts. Try simply plugging a cord in & out a few times to work the switching contacts. Or try a TRS (stereo) patch cord from send to return.

This is assuming you have the earlier model, rather than the Ultimate Chorus DSP.

Good luck!

[Notafraid]

Mark,

I appreciate the info. Based on your fault isolation procedures, I simply unplugged the left speaker, and low and behold, no sound came from the right speaker… So, let me re-state my problem… One of my speakers is not making any sound…


I took an old car speaker and hooked it up to the right channel, and got some sound out of the right channel. Looks like my problem is that I have a blown speaker...


Looks like $40.00 here and I will be set: http://www.musiciansfriend.com/produ...ker?sku=660182

[Notafraid]

Ok, I got the speaker, got it in, it sounds great. One thing I am experiencing however is a popping sound. The amp is a real clean and loud sounding amp. I mean loud. At level 2-3 volume you can feel a wall of sound coming from the amp. I mean it rattles things in my sons room. At that point if I mute the strings, and strum once real hard, the amp makes a popping sound. Other than that it sounds great. What would cause that? Also, is there a break in period for this new speaker?

Thanks

[Mark Black]

Glad to hear it's coming along!

Regarding the popping - does it happen just once during the hard strum or in repetition? Also if you whack the top of the amp real hard with your fist can you make it pop?

I immediately lean towards possible cracked solder joints based on my experience with solid-state Fenders of that era, popping due to which should be heard with a hard whack or two.

Another possible popping noise during hard percussive play could be the sound of a speaker exceeding its maximum allowable excursion with the voice coil support tube actually "hitting bottom".

And then there are a myriad of other possibilities of course...

My personal opinion on the "breaking in" of speakers is that they don't require a break in period (like a car engine for instance) in order to work properly. They do change character slightly as they age due to the changing flex characteristics of the spider, compliance, and cone itself first as they get settled in for the majority of their life and then later as these structures start to lose flexibility and begin to break down toward the end of usability.

[Enzo]

I agree, speakers do break in and settle into their sound, but they don't need a breakin to simply work right.

Yes, please ball up your fist and whack the top of the amp. If that makes it pop or do anything, somethjing is loose inside. Might turn the reverb down first though.

Certainly a loose tube socket could react to vibration from the speaker.

[Mark Black]

Might turn the reverb down first though.

Ha! Very good advice! I've made an ass out of myself several times at work by forgetting that one. Sure gets everyone's attention...

[Notafraid]

Sorry guys, false alarm. I can’t even duplicate the problem again. I did try balling up my fist and hitting the amp several times. I cranked it past 3, and really hit some chords hard and stuff. It does tend to loose a little of it’s utter cleanness for a second, and sounds a little distorted. Anyway, I don’t know if that’s natural or not, but I can’t make that pop occur.

So on an aside, do any of yall know this particular amp very well? The speakers have pretty small looking magnets. Do they suck? I would like to have some nice vintage Celestons in the amp, but I have blown my whole budget already on it, and the wife is even making me sell an old Randal 1-12 amp and Squire guitar to make up for the cost of the amp. So far I have $180.00 it. I would have to nearly double that to replace the speakers.

[Enzo]

Do they suck? The amp is there in the room with you. Play through it. How does it sound? You tell us if they suck.

[Notafraid]

They sound fine to me, but I was wondering more if they tended to get blown a lot or something.

Good news for anyone who is trying to figure out the popping noise! It’s back. Well sort of. That is, I know how to duplicate it now. It’s something that only happens out of the right speaker (which is the new speaker), and it only happens when the chorus is on. It does not happen when the chorus is off. I did try pounding the amp when the chorus was on, and could not duplicate it. Any ideas?

[Enzo]

Sure, something is wrong with the chorus circuit. Won't likely be simple for the layman to repair.

[Notafraid]

The odd thing is that the CHorus works fine at lower levels. There is only a problem at higher volumes.

[Enzo]

Well if there is a DC offset that doesn't belong for example, your signal could bump into it and clip.