Fender Jazzmaster Ultralight - cuts out

**DanH8482** · 07-23-2014, 10:02 PM

Hello Everyone,

I recently acquired a Fender Jazzmaster Ultralight that has been cutting out intermittently. I took it to a technician and he could not get it to recreate the issue. Of course, once I took it back home, while playing continuously for about an hour, it cut out 7 or 8 times but never for more than a second or two. At the tech's suggestion, I turned the effects all the way off and I could not recreate the problem again, but I only played for another 15 minutes then. It seems to happen only after a lot of playing, at least more than 10 minutes. I'm not sure if the effects had something to do with it. I've tried it with several guitars and cables and have eliminated those as the culprit.

Has anyone here experienced a similar circumstance with this amp?

Thanks!

**jorgemg1984** · 07-24-2014, 05:54 AM

I had that with mine and my tech did some rewiring and it solved it (and the noise). I also think if you a higher ohm cab (like 4 ohm) the problem never appears.

**Greentone** · 07-25-2014, 11:01 AM

What effects? If you are using signal boosting effects, i.e., distortion pedal, you could induce blocking in the inverter stage. This causes the amp to crap out. I have an old tube amp that on ten cuts out. Back off the volume...everything is fine. The problem is that the 12at7 blocks at extremes. You could present your inverter with a similar problem using hot humbuckers and an aggressive pedal.

**Greentone** · 07-25-2014, 11:18 AM

I just looked at the schematic for your amp. Nice, modern circuit. Class D power amp delivers lots of power for its size using eight mosfets. Heat mgt will be important in a small box but Fender has considered that. Of course, that could be your problem. The amp has a protection circuit to shut down if heat gets too high. Looks like Fender is trying to tap the Clarus/RE market with this one.

**monkmiles** · 07-25-2014, 10:57 PM

What speaker/cab are you playing it through? How many ohms? Are you using proper speaker cable?

Originally Posted by Greentone

I just looked at the schematic for your amp. Nice, modern circuit. Class D power amp delivers lots of power for its size using eight mosfets. Heat mgt will be important in a small box but Fender has considered that. Of course, that could be your problem. The amp has a protection circuit to shut down if heat gets too high. Looks like Fender is trying to tap the Clarus/RE market with this one.

Well, it was a short lived run. They quickly gave up on it and on tapping the Clarus/RE market. I had one when they first came out and liked it alot.

**AlsoRan** · 07-25-2014, 11:09 PM

Originally Posted by hallpass

Well, it was a short lived run. They quickly gave up on it and on tapping the Clarus/RE market. I had one when they first came out and liked it alot.

Did you sell yours, Hallpass?

**monkmiles** · 07-25-2014, 11:47 PM

Originally Posted by AlsoRan

Did you sell yours, Hallpass?

Yes, a very long time ago. I've always liked it though...probably my favorite solid state amp I've played. These days I'm a fender tube amp player.

**AlsoRan** · 07-26-2014, 12:31 AM

Originally Posted by hallpass

Yes, a very long time ago. I've always liked it though...probably my favorite solid state amp I've played. These days I'm a fender tube amp player.

I believe you had the SuperchampXD as well, did you not HP? Did you sell that as well.

I have both the XD and the Ultralight and am pretty happy with both of them. I thought maybe they were both Keepers for you.

Could you tell me also what your amp of choice is now?

Thanks.

**AlsoRan** · 07-26-2014, 12:34 AM

Sorry if I am hijacking the thread, OP. My Ultralight, which I bought used last year, is still doing well. We had a thread that a member named Wildcat started when his Jazzmaster Ultralight failed on him. I think he was able to get it fixed. Look it up or PM the gentleman, and you might be able to formulate a plan of attack to get your amp fixed.

Use Google and you should have no problem finding the thread.

Good luck.

**monkmiles** · 07-26-2014, 07:36 AM

Originally Posted by AlsoRan

I believe you had the SuperchampXD as well, did you not HP? Did you sell that as well.

I have both the XD and the Ultralight and am pretty happy with both of them. I thought maybe they were both Keepers for you.

Could you tell me also what your amp of choice is now?

Thanks.

I had a Super Champ xd but now have the x2 model. I mostly use a Princeton reverb reissue with a 12" speaker. Then I also have a 1971 silverface Bandmaster I made into a 2x10 combo. Oh and recently got a fender champion 600 too.

**docbop** · 07-26-2014, 08:06 AM

Originally Posted by hallpass

I had a Super Champ xd but now have the x2 model. I mostly use a Princeton reverb reissue with a 12" speaker. Then I also have a 1971 silverface Bandmaster I made into a 2x10 combo. Oh and recently got a fender champion 600 too.

How do you like the Bandmaster? Everyone goes looking for the BF Bassman, but the Bandmaster is essentially the same amp add vibrato.

**monkmiles** · 07-26-2014, 09:27 AM

Originally Posted by docbop

How do you like the Bandmaster? Everyone goes looking for the BF Bassman, but the Bandmaster is essentially the same amp add vibrato.

I absolutely love it now. I recently had it blackfaced and now it sounds sweet.

The bassman is similar but has a little more gain because of the lack of vibrato and a bigger output transformer.

I actually upgraded my Bandmaster output transformer at the same time as blackfacing it. It's now the classic ab763 circuit with the same power output transformer as the baseman and super reverb. In its 2x10 combo I think of it as a Vibrolux minus reverb in my mind. I just add a reverb pedal. Not hugely heavy at 45lbs and good power and headroom...more than I usually need.

**docbop** · 07-26-2014, 11:10 AM

Originally Posted by hallpass

I absolutely love it now. I recently had it blackfaced and now it sounds sweet.

The bassman is similar but has a little more gain because of the lack of vibrato and a bigger output transformer.

I actually upgraded my Bandmaster output transformer at the same time as blackfacing it. It's now the classic ab763 circuit with the same power output transformer as the baseman and super reverb. In its 2x10 combo I think of it as a Vibrolux minus reverb in my mind. I just add a reverb pedal. Not hugely heavy at 45lbs and good power and headroom...more than I usually need.

Thanks I didn't know about the output transformer, the transformers are big part of the sound.

**DanH8482** · 07-27-2014, 11:53 PM

Thanks everyone, I had not checked in on this for a couple days and didn't see all these replies.

I have the original speaker cabinet and Speakon cables, so I don't believe there would be any mismatch issues. Right now my tech has the amp again and he will be keeping at it until he can recreate the issue in his shop and then go from there.

As for heat issues, I know practically nothing about electronics so that would be way over my head but I trust the tech would know what to do if it is the case.

Im hopeful for this to be a reliable piece of gear. It seems like the perfect alternative to my heavy tube amp that I love to play but hate to carry.

I'll be sure to look up the above mentioned thread and PM the member who started it too. Thanks for the tip.

**phil79** · 08-25-2014, 03:31 AM

Hey DanH8482,

have you solved the problem? I have the same issues with my JMUL....

all the best...

phil

**DanH8482** · 08-25-2014, 07:48 AM

Hi Phil,

The tech I went to initially had a hard time getting it cut out but finally did after a lot of time playing on it. He said he cleaned up all the connections in the head and the cabinet and it has not cut it out since. Its hard to say if its fixed for good because it only happened a couple times in many hours of playing and hasn't happened since. I've read that the ultimate solution is to replace the speaker with a 4 ohm instead of the 2 ohm, but I have not done that. I've switched over to an Acoustic Image Clarus now that I'm playing more steel-string acoustic gigs in addition to nylon string, and I am selling the JMUL. If I were to keep it, I would replace the speaker at the first sign of any further cutting out.

What have you tried to do so far to resolve the issue?

**phil79** · 08-28-2014, 05:08 PM

I've only changed the speaker to one with 8 ohm, but it continues to cut out.
I've just bought it used but I think I'm sending it back. It sounds great when it's working, but it's too expensive for an amp that has such problems from the start...