Fender m80 chorus

brick8 · 06-30-2006, 07:12 PM

I am trying to troubleshoot my solid state Fender M80 Chorus amp. Does anyone have a schematic or know where I can find one?

Thanks!

cjlectronics · 06-30-2006, 07:45 PM

What is the problem? I've worked on a few of the SS Fender amps and some were just simple soldering problems and one was just a bad MOV at the power input.

CJLectronics

brick8 · 06-30-2006, 11:04 PM

I don't get any sound when playing through the clear channel (main inputs). The green clear channel light does not go on (but the power light on the overdrive channel goes on). The only way I can use it is by plugging my guitar into the effects loop input. I get some sound that way but not much and none of the controls on the front of the amp will do anything. I opened up the amp and checked the fuse and it was OK.

Enzo · 07-01-2006, 01:40 AM

Send me an email with Fender M80 CHorus as the subject line and ask me for the schematic.

brick8 · 07-01-2006, 06:28 PM

Thanks for the help. I tried plugging my guitar into a smaller amp and then ran a patch cord from that amp's headphone jack into the effects loop jacks (didn't really matter which one) of the M80 and got plenty of sound. I got no sound when running the patch cord into the input jack of the M80. I could sort of regulate the sound using the volume control of the first amp.

If I can't fix the M80 could I just buy a used preamp and plug it into the M80 this way? Would I burn out one of the two by doing so?

cjlectronics · 07-01-2006, 07:06 PM

I wouldn't be surprised if the input jack just needs a re-solder job? It is very common for these Fender amps to have broken or cold solder joints on the input and output jacks.

You'll have to pull the whole PC board out which is not difficult but time consuming. Make sure you mark the cables before you remove them and just take your time.

brick8 · 07-02-2006, 01:10 AM

I'll check that before doing anything else. However, the lights on the preamp part don't go on, so it seems there might be a bigger problem.

drewl · 07-29-2006, 06:23 PM

Is the chorus on these amps supposed to be on both left and right outputs?
I have one with chorus only on the right output, don't think it's correct.
Enzo, I emailed you for a schematic if you have one, thanks.

Enzo · 08-01-2006, 03:27 AM

Drawing on the way

Enzo · 08-01-2006, 03:40 AM

Look at the mono effects loop, which is the preamp out. After C31, the dry signal goes to U6B and on to the left power amp, and it also branches through the chorus circuit and back to U6A for the right PA. U8A switches the R PA between that chorus or the dry signal.

dr7756 · 10-03-2006, 03:42 AM

Hi! I'm trying to work on a Fender M-80 as well (1x12 combo, no chorus). I'd be eternally thankful if someone had a schematic they could send me!

Enzo · 10-03-2006, 09:02 AM

Send me an email with Fender M-80 as the subject line and ask for it.

tmenzo at msn dot com

Rock-it Robby · 01-19-2007, 07:11 PM

Enzo, please send schematic of M80 to rob@engineeredautomotive.com, thanx.
R

Enzo · 01-20-2007, 12:34 AM

Doesn't work that way Robby. I am happy to send it, but please follow the instructions in the post above yours.

Also, since there are several M80s, please send me the complete model name, and IMPORTANT list the items across the control panel in order. This will ID your amp for me.

I am on a dial up and don't want to send four large files

ACEE · 01-22-2008, 08:22 PM

Hey everyone, I stumbled upon this site via a google search for an M80 schematic. I ordered a schematic from Fender and received a lot of fluff information and 1 of 2 pages of the actual schematic. I noticed there are no power electronics on my schematic and was hoping someone had the second page. The page I have is 037023. The M80 I have is the head to a half stack with matching speaker cab. Can someone help me out? Thanks a lot.

dr7756 · 01-22-2008, 11:58 PM

I have schematics for an M-80 Combo, not the model with chorus. It's a PDF file and it's not very easy to read in places, but you're welcome to it.

http://homepage.mac.com/d.c.rogers/

Enjoy!

Enzo · 01-23-2008, 07:05 AM

I don't consider parts lists fluff.

I have put the M-80 Chorus file on the Ampix.org

COntact Fender and tell them the page is missing from the file. That way they can correct the file.

There are:
M-80
M-80 Preamp
M-80 Chorus
M-80 Bass

They are not the same.

ACEE · 01-23-2008, 05:05 PM

Thanks for your help dr.

I agree with you Enzo. I wish they had sent me a parts list

. All I received were the first page to the schematics, a board layout, a block diagram or two, and a bunch of pages on different knob configurations <-- fluff. Thanks a lot for your upload, this is exactly what I'm looking for.

Now the fun part: determining what's wrong with my amp. I noticed some similiar M80 problems on this forum so I'm going to check those out before I post anything else.

Thanks again.

06-30-2006, 11:04 PM	#3
brick8 Junior Member Join Date: Jun 2006 Posts: 4	no sound through clear channel I don't get any sound when playing through the clear channel (main inputs). The green clear channel light does not go on (but the power light on the overdrive channel goes on). The only way I can use it is by plugging my guitar into the effects loop input. I get some sound that way but not much and none of the controls on the front of the amp will do anything. I opened up the amp and checked the fuse and it was OK.

07-01-2006, 06:28 PM	#5
brick8 Junior Member Join Date: Jun 2006 Posts: 4	may just be the preamp Thanks for the help. I tried plugging my guitar into a smaller amp and then ran a patch cord from that amp's headphone jack into the effects loop jacks (didn't really matter which one) of the M80 and got plenty of sound. I got no sound when running the patch cord into the input jack of the M80. I could sort of regulate the sound using the volume control of the first amp. If I can't fix the M80 could I just buy a used preamp and plug it into the M80 this way? Would I burn out one of the two by doing so?

07-01-2006, 07:06 PM	#6
cjlectronics Supporting Member Join Date: May 2006 Posts: 165	Try resoldering the input jack I wouldn't be surprised if the input jack just needs a re-solder job? It is very common for these Fender amps to have broken or cold solder joints on the input and output jacks. You'll have to pull the whole PC board out which is not difficult but time consuming. Make sure you mark the cables before you remove them and just take your time.

10-03-2006, 03:42 AM	#11
dr7756 Junior Member Join Date: Oct 2006 Posts: 2	Fender M-80 Combo Hi! I'm trying to work on a Fender M-80 as well (1x12 combo, no chorus). I'd be eternally thankful if someone had a schematic they could send me!

01-19-2007, 07:11 PM	#13
Rock-it Robby Junior Member Join Date: Jan 2007 Posts: 1	Fender M80 Enzo, please send schematic of M80 to rob@engineeredautomotive.com, thanx. R

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06-30-2006, 07:45 PM	#2
cjlectronics Supporting Member Join Date: May 2006 Posts: 165	What is the problem? I've worked on a few of the SS Fender amps and some were just simple soldering problems and one was just a bad MOV at the power input. CJLectronics

07-01-2006, 01:40 AM	#4
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	Send me an email with Fender M80 CHorus as the subject line and ask me for the schematic.

07-02-2006, 01:10 AM	#7
brick8 Junior Member Join Date: Jun 2006 Posts: 4	I'll check that before doing anything else. However, the lights on the preamp part don't go on, so it seems there might be a bigger problem.

07-29-2006, 06:23 PM	#8
drewl Senior Member Join Date: Jun 2006 Posts: 538	Is the chorus on these amps supposed to be on both left and right outputs? I have one with chorus only on the right output, don't think it's correct. Enzo, I emailed you for a schematic if you have one, thanks.

08-01-2006, 03:27 AM	#9
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	Drawing on the way

08-01-2006, 03:40 AM	#10
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	Look at the mono effects loop, which is the preamp out. After C31, the dry signal goes to U6B and on to the left power amp, and it also branches through the chorus circuit and back to U6A for the right PA. U8A switches the R PA between that chorus or the dry signal.

10-03-2006, 09:02 AM	#12
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	Send me an email with Fender M-80 as the subject line and ask for it. tmenzo at msn dot com

01-20-2007, 12:34 AM	#14
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	Doesn't work that way Robby. I am happy to send it, but please follow the instructions in the post above yours. Also, since there are several M80s, please send me the complete model name, and IMPORTANT list the items across the control panel in order. This will ID your amp for me. I am on a dial up and don't want to send four large files

01-22-2008, 08:22 PM	#15
ACEE Junior Member Join Date: Jan 2008 Posts: 4	Fender M80 Chorus Hey everyone, I stumbled upon this site via a google search for an M80 schematic. I ordered a schematic from Fender and received a lot of fluff information and 1 of 2 pages of the actual schematic. I noticed there are no power electronics on my schematic and was hoping someone had the second page. The page I have is 037023. The M80 I have is the head to a half stack with matching speaker cab. Can someone help me out? Thanks a lot.

01-22-2008, 11:58 PM	#16
dr7756 Junior Member Join Date: Oct 2006 Posts: 2	I have schematics for an M-80 Combo, not the model with chorus. It's a PDF file and it's not very easy to read in places, but you're welcome to it. http://homepage.mac.com/d.c.rogers/ Enjoy!

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01-23-2008, 07:05 AM	#17
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 9,266	I don't consider parts lists fluff. I have put the M-80 Chorus file on the Ampix.org COntact Fender and tell them the page is missing from the file. That way they can correct the file. There are: M-80 M-80 Preamp M-80 Chorus M-80 Bass They are not the same.

01-23-2008, 05:05 PM	#18
ACEE Junior Member Join Date: Jan 2008 Posts: 4	Thanks for your help dr. I agree with you Enzo. I wish they had sent me a parts list . All I received were the first page to the schematics, a board layout, a block diagram or two, and a bunch of pages on different knob configurations <-- fluff. Thanks a lot for your upload, this is exactly what I'm looking for. Now the fun part: determining what's wrong with my amp. I noticed some similiar M80 problems on this forum so I'm going to check those out before I post anything else. Thanks again.

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