Fender Rumble 25 Speaker Rattles

[jimirb]

I got a pdf of the schematic and parts list from Fender today for the solid state Rumble 25. I'm not sure if this forum allows attachments, but I'll be glad to send it to anyone who needs it. Also learned the correct email for support from Fender is consumerrelations@fender.com

 

[tubelectron]

Rumble 25 c38 and c21

I know these posts were several years ago, but I just found....and followed....them. I had the same crackle problem. I thought it was the speaker but decided the c38 fix was a cheap 1st step. I replaced c38 (a 2.2 mfd 50 v) with 10 mfd 50 V and replaced c21 (which IS 10 mfd 50 V.) As long as I was in there I replaced the 2 big 2200 mfd 35 V caps (c19 & c20 I think) just for good measure.

For less than $5, my crackle was completely fixed.

Thanks for those who posted the information.

I have a Fender Rumble Bass 25 which had exactly the same problem as described in this thread, and I applied partially the same solution as described above, that is to say :

C38 : 2u2/25V --> 10u/50V (the most important change, IMHO)
C21 : 10u/25V --> 10u/50V

And that unbearable buzz/crackle problem is fixed definetly . The amp plays nickel-chrome, all is OK, no issue . Great...

These caps are very easy to locate as their number is labeled on the PCB. More simple, you die...

Thanks for that simple and efficient tip !

A+!

 

[saudio78]

Hi everybody,

same problem with mine
I've changed C38 only and it works fine now ! thanks to audiohead

 

[bigbluedry]

I have looked all over the Fender Rumble 25 and Frontman 25B schematics. I can't find the C38 capacitor. Would you kindly tell me where it is located on the drawing and the board?

Thanks

 

[mikeskory]

Here it is 11 years later and I've got the same problem in a customer's Rumble 25. I thought I could fix it quick with a new U6 output IC. Lol! Anyway I read about replacing C38 and C21 with 10mfd so I'll try that tomorrow. Did you change the ca3080? I thought about it. Hopefully you guys are still in nthe business. Maybe I should try a new post..

 

[Rippli]

And another one! January 2018 here with a similar story. Got a free Rumble 25 that distorted and made horrible noises above half volume. Checked loudspeaker = fine, & was close to scraping it when I found this thread.
Changed c38 to 10mfd/50v and replaced c21 with the same.
Less than £2 and totally fixed!
Very happy with that! Time to learn that bass now!
Thanks Audiohead!

 

[famousmockingbird]

I wonder if it's not the cap that is bad but actually a cold solder joint that cabinet vibration from bass notes causes an intermittent connection.

Maybe the next person with the same issue comes across this thread can try resoldering C38 before ordering parts to see if it fixes the crackle. Crackle for me is almost always a bad connection.

 

[Rippli]

I wouldn't describe it as crackle - more distortion... Could be bad joint I guess? but why would it always affect the same capacitor(s) ?

 

[famousmockingbird]

I wouldn't describe it as crackle - more distortion... Could be bad joint I guess? but why would it always affect the same capacitor(s) ?

Okay yes distortion at the output would be a bad cap.

 

[jetbat]

I to have this problem and it seems there are multiple versions of this amp with different pcb's and schematics. I also do not have a C38 in this amp. I attached a piece of the limiting circuit. If someone who has fixed this problem could point out the offending capacitor on this picture it would be much appreciated.

 

[koozoop]

Good evening.
Exact same problem here, only with Fender Rumble 25LT. Sounds distorted on lower frequency registers both speaker and headphone out. I don't have the schematics (already emailed Fender, I hope they will send me something...) but I opened the amp and had a look at the power amp pcb. I can't understand many things (I'm not an electronics expert, just a diy'er) but as far as I can see the electrolytics look ok. Can someone guide me to locate the faulty component?

Thank you in advance

 

[JMFahey]

As mentioned above, Fender (like many others) often recycles commercially successful names, in very different products.

Yours is a late model one, visibly a "digital" Class D amplifier and certainly fed from a "digital" switching power supply, both VERY different from what you find in older units, so "their" troubleshooting does not apply much.

My first impression would be your amp is simply clipping above a certain volume.

Various red flags point to that: low frequencies (poorly heard), small speaker on a small cabinet (poor bass reproduction), need for a high-ish playing level, etc.
Don't think something is broken, "it is what it is"

To play alongside a drummer you need 80-100W minimum, into a reasonably good 12"-15" speaker, you need to "move air".
Sorry.