Fender Ultimate Chorus

drp555 · 03-10-2008, 08:47 PM

I have a Fender Ultimate Chorus, its about 9 - 10 years old, not the DSP. It now has a horrible hum when turned on. Even with no guitar plugged into the amp. If I turn the chorus on, the hum gets even louder and bassier. Sound still comes out if I plug a guitar in and play, but there's crackle and fizz with all the notes.

Any help or thoughts would be appreciated.

cbarrow7625 · 03-10-2008, 10:04 PM

Two things come to mind immediately:

1.) Cracked ground trace (input jack maybe?) that is disrupting the ground continuity in the circuit.

2.) Filter caps. Have you checked them? Do you have the proper DC running through the amp? How much ripple do you meause on the DC rails?

Filter caps would be a 120Hz hum. Ground trace would be 60 Hz. Can you tell which it is? I don't know what piano notes those two frequencies are off the top of my head but I'm sure someone else here can tell you. If you can figure out the tone, you will be that much closer to solving your problem.

Enzo · 03-11-2008, 01:05 AM

FLip the main board over and check the solder to the main filter caps. I bet it is cracked - resolder them.

drp555 · 03-14-2008, 12:48 AM

Thanks guys. I got a chance to check out the board today. Turns out one of the filter caps did have a cracked solder joint. I fixed that up and now everything is good.

grcarson · 03-17-2008, 01:05 AM

had the same problem. Thanks for the fix.

Showey · 06-01-2008, 03:02 PM

Had the same issue here. Fixed that but the reverb doesnt seem to work although when I tap on the reverb unit I can hear the effect thru the speakers. Any ideas?

Gtr_tech · 06-02-2008, 09:57 PM

Quote:

Originally Posted by Showey

Had the same issue here. Fixed that but the reverb doesnt seem to work although when I tap on the reverb unit I can hear the effect thru the speakers. Any ideas?

Lunched rev drive IC is likely. Or a bad coil/connection to the coil on the drive side.

Showey · 06-05-2008, 04:03 AM

I found it. bad coil on the INPUT side of the reverb tank.
New reverb can installed 20.00 from ebay and all is well!
Thanks!

Showey · 06-05-2008, 10:59 PM

Today I swapped it for a Peavey Delta Blues 115 Tube Combo Amp.
I think its a good thing?

03-10-2008, 08:47 PM	#1
drp555 Junior Member Join Date: Mar 2008 Posts: 2	Fender Ultimate Chorus - bad hum I have a Fender Ultimate Chorus, its about 9 - 10 years old, not the DSP. It now has a horrible hum when turned on. Even with no guitar plugged into the amp. If I turn the chorus on, the hum gets even louder and bassier. Sound still comes out if I plug a guitar in and play, but there's crackle and fizz with all the notes. Any help or thoughts would be appreciated.

06-01-2008, 03:02 PM	#6
Showey Member Join Date: May 2008 Posts: 26	Ultimate Chorus issues. Had the same issue here. Fixed that but the reverb doesnt seem to work although when I tap on the reverb unit I can hear the effect thru the speakers. Any ideas?

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03-10-2008, 10:04 PM	#2
cbarrow7625 Senior Member Join Date: Mar 2007 Location: Philadelphia suburbs Posts: 366	Two things come to mind immediately: 1.) Cracked ground trace (input jack maybe?) that is disrupting the ground continuity in the circuit. 2.) Filter caps. Have you checked them? Do you have the proper DC running through the amp? How much ripple do you meause on the DC rails? Filter caps would be a 120Hz hum. Ground trace would be 60 Hz. Can you tell which it is? I don't know what piano notes those two frequencies are off the top of my head but I'm sure someone else here can tell you. If you can figure out the tone, you will be that much closer to solving your problem.

03-11-2008, 01:05 AM	#3
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,288	FLip the main board over and check the solder to the main filter caps. I bet it is cracked - resolder them.

03-14-2008, 12:48 AM	#4
drp555 Junior Member Join Date: Mar 2008 Posts: 2	Thanks guys. I got a chance to check out the board today. Turns out one of the filter caps did have a cracked solder joint. I fixed that up and now everything is good.

03-17-2008, 01:05 AM	#5
grcarson Junior Member Join Date: Mar 2008 Posts: 1	had the same problem. Thanks for the fix.

06-05-2008, 04:03 AM	#8
Showey Member Join Date: May 2008 Posts: 26	I found it. bad coil on the INPUT side of the reverb tank. New reverb can installed 20.00 from ebay and all is well! Thanks!

06-05-2008, 10:59 PM	#9
Showey Member Join Date: May 2008 Posts: 26	Today I swapped it for a Peavey Delta Blues 115 Tube Combo Amp. I think its a good thing?

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