Rumble 100 schematic I really need this to find the part no. for burned components other wise I cannot say except I bought the thing and the speakers were unpluged and It looked like some one plugged it up any way and smoked several components. If you will or can help me contact me at this email address . lloyd111345@windstream.net

The schematic shows it as a standard 1/4 inch stereo plug. Wire the ground common to both switches (Channel and DFX), the ring to one switch and the tip to the other...I.E. ground (sleeve) to ring for one switch and ground to tip for the other. You'll have to experiment with which switch operates what function and label them accordingly.

Try this:

http://support.fender.com/schematics/bass_amplifiers/Rumble_Bass_schematic.pdf

Try plugging another sound source into the unit. The buzz MAY be pickup of magnetic fields in your guitar pickup that clobber your notes from the strings. Bad guitar cables are another possibility. By putting clean music from say a CD player into the unit you can find where the source is. If the CD player generates the same noises, then likely you have a failure of filter caps in the amp or other component failures. Also make sure your guitar can't "hear" the amp as feedback can do strange things.

VERY common problem... this is why you ALWAYS loop your cable through the handle. One trip over a guitar cable and the yank sideways destroys the jack... AND the jacks are really weak and poor to start with... Take the thing in for repair, or if you are electronically adept replace the jack yourself. MOST of these have the jack soldered to a circuit board and one often has to remove all the front knobs and the nuts holding the volume controls and move the bord back to remove and replace the jack...

That may be minor or very major. Open the unit and look for damage.

Best case, loose debris in the unit shorted something in the power supply. Probably replacing one or a few small components to repair.

Worst case, debris or failed component has burned large area of board. This would be fatal.

I have schematic so let me know what you find as source of the smoke. Note that most of these use surface mounted parts and require a bit of soldering skill to repair.

Here is the schematic:http://www.fender.com/support/amp_schematics/pdfs/Rumble_Bass_Schematic_-B21.pdf Check the tubes to see if one is loose in its socket. Do not attempt to repair this yourself unless you have amplifier repair experience as it is easy to get a bad or life threatening shock without the correct test gear and troubleshooting procedures.I hope this helps.

Suspect the input jacks. Wiggle them and see if you get anything. They get yanked sideways because the musicians don't loop their cord thru a handle and they get yanked sideways.

Also you can try spraying sparingly CRC226 into the switches and pots. You can get it at Home Depot in the electrical department.

Hi there. If 10" speakers are 8 or 16 ohm, parallel them. If they are 4 ohm, series them. if "External speaker" output is rated down to 4 ohm. If no external speaker jack, you'll have to tap into existing speaker jack with a "Y". Check the minimum ohm load for the amp.
Thanks
Paul

I just fixed my bass amp with a similar problem last week: the problem is related to a loose connection on the PCB board (likely).
A bass amp is a rough place for circuitry: the low rumble and power shake a bass amp more than a guitar amp.
In my case, the power transistors needed to be re-soldered and then the grounding bolts and screws needed to be removed and cleaned because the connection was bad. Remember that when two different metals needed for an electric connection are toughing, there is the likelyhood that corrosion WILL happen.
My bass amp did basically the same thing yours did: sounded good at low volumes, but at higher volumes it would act up.
In short, there is nothing you can do (unless you are a repair person): you need to take it to a local music shop and have a tech fix the intermittant contact problem: someone who knows what they are doing should only take an hour at most.

Hope that helps!
-mike

Replace C21 (10uF/50V) and C38 (2.2uF/50V) and it will work great.