Line 6 Spider III 15W- My Bass and Drive knobs arnt working... my mid and treble seems to be fine plus all my channels and effects but just those two knobs...and its buggin the **** out of me.... any advice on how to fix this? something simple at best. thank you : }

Provided that you're not using any external devices, and plugging the guitar directly into the amp, this sound solely like an internal switching problem. Meaning...it will require service. Chips can get faulty like that sometimes. If you're using any external pedals, remove them and see if it happens. If not...the pedal(s) are to blame.

you may have a loose connection

There is probably a power supply failure or with the power on reset circuit. Likely low voltage to the logic electronics. This is NOT DIY unless you are familiar with electronics.

The reverb should be quite strong. I would first look at the reverb volume pot R42 which is a 50K pot. I would also check the voltages on the test points near U4 (TLO-72 op amp tp13 and tp14) which amplifies the signal coming out of the box. It is possible the box has low power levels as well.
The problem is going to be around that section of the board if it isn't a dirty or dead(ish) pot.


The reverb should be noticeable enough to be annoying ;-]

TRY CHANGING THE KNOB SWITCH.

Read this cut and paste and verify compatibility as a first step:

<<<
*FBV is not compatible with Spider II 15 or Spider III 15.

**FBV is only compatible with POD 2.0 units with pedal jacks labelled "FBV Pedal." It is not compatible with older units which have pedal jacks labelled simply "Pedal."

(NOTE: FBV is NOT compatible with Ax212™, Flextone™ I, II or HD, POD® Pro, Bass POD®, Bass POD® Pro and Spider™.)
>>>

Note there are apparently several versions. Check compatibility at this site:

http://line6.com/footcontrollers/fbv.html

translation: In the amplifier Line 6 Spider 3, is it possible to connect effect pedals of other makes apart from Line 6.
Creo si, pero primo del amplificador con una corda guitarra.
I think that you can, just add them to the input

If this has a digital effects processor read on.., I had a SIMILAR problem on a Behringer GX110.

The electrolytic filter cap for the 5 volts of the DSP effects had gone bad. The 5 volts was dipping when the DSP reset and it would repeatedly reset causing a clicking at about once a second. 50 cent part fixed it. The part is a little undersized electrically so is more prone to failure in the unit I have.

That particular one had the DSP as a seperate board with its own 5 volt supply from the main transformer.

Make sure both the master volume and channel volume is up. If that does not do it, take it to the nearest Line 6 repair center.
http://line6.com/support/serviceCenters/

Insain is distorted but cleen is not