Pot broke off

That , as far as I know, can only be bought through Behringer. They will probably NOT sell it to you or help you. THEY want you to buy a new one. This is one of those companies that has most of their semiconductors marked and labeled with odd numbers of their own so a technician will have no clue what values they are or where to get them. Behringer is the one main brand of equipment I have never been able to get ANY parts for other than colored resistors or diodes, some caps, switches and lights. Finding a schematic is easier done than to actually find replacement parts. Sorry, wish I could help more while being as honest as possible.

Best bet is probably Mouser, http://www.mouser.com Search for the individual catagory. While there is no direct cross, you should have an audio taper or logrithmic tape- similar graphs, but slightly different. It might do well to get one of each and use the one that matches the response of the others.

If however you have a loudness tap- usually 40 percent, that changes the ballgame. Mouser would still likely be the best bet. Over 800 items for pots in the general search at 50K

If your outer trace is intact, you can measure that with a meter to verify that is the range you need.

The VR96 is a 50K "G" taper or "graphic taper" pot. Lots of luck trying to find that in a catalog... I finally got a scrapped piece of mixer board and salvaged one. The G taper is not stocked by any of the vendors like Digikey or Mouser here. Full Compass is the Behringer part distributor and I waited 6 months and got no delivery of one of these pots. The effects selector is a rotary encoder quadrature type. Use the Mouser.com catalog. Search for Encoder, then select ALPS manufacturer and then try to match up mounting and type using the spec drawings... with push switch also... Again, if you want to try Full Compass, you can call Behringer rep in Woodinville WA USA to get the Behringer part number and incident number to see if Full Compass might have one in stock.

Here is the maintenance schematics for your unit...VR96 is on page 7 of 32. :

http://elektrotanya.com/behringer_ub2442fx-pro_sm.pdf/download.html

Scroll down to "get manual" and click on it to download. IGNORE other download links as they are for viewers, etc.

Note, You may have to cut off a shaft on replacement to the right length to match existing shaft.

You can. If it is a tone control you may have a reduced effective rotation range. Probably this won't matter to most people. As a volume replacement, replacing with a lower value may reduce treble slightly, and a higher value increase treble slightly. It is quite a small effect though and you may even like it better.

The sliders in almost all of the EQ's in Behringer are linear taper (B). The values are usually 50K. Fo replacement make sure you get matching mounting spacing. Almost all Behringer pots are made by ALPS.
Note that the rotary volume controls are G (graphic) taper, often 50K and are hard to get. trying to get these from the Behringer parts distributor was futile... gave up after 4 months wait.

Chaances are the potentiometer element was fatally damaged by the force when the knob was broken off.

You will need to have the unit serviced and getting the correct part is important to match the shaft, mounting, etc as well as the electrical characteristics.

The clean treble control is a 20K ohm, "B" taper pot (audio). ALL the signal for the clean channel goes through this so if pot is destroyed, clean channel will be dead.

Best thing is to call Marshall "parts" and get exact replacement. Note that sometimes the circuit board is cracked as a result of these accidents. This unit looks like the controls are VERY vulnerable to damage. I would make a cover to prevent damage from handling.

Another thing is to ALWAYS loop your guitar cable through the handle so tripping over it won't break the input jack which is a COMMON occurence.

You need to replace the potentiometer with the broken shaft. You can open the unit and try to get a part number or go to Behringer parts to get an exact replacement. The pot must be matched for value, taper, and mounting and shaft dimensions.

It appears that both these use a 50K pot in the identical circuit and it is UNLIKELY they re-engineered very much so it is likely they use the same pot.

Behringer parts service should be able to tell you.

Did you mean the treble control potentiometer (knob)?

This was posted as an amplifier problem, but since you mentioned that the use of the treble (button?) on the guitar is causing the clicking, i would have the treble potentiometer checked first.

It could have a loosely soldered or broken wire on any of the tabs, oxydized slider contacts, bad ground (negative) connnection, possibly dirt or damage on the resistive track inside the pot.

A broken wire can easily be resoldered, but if there is internal damage or oxydation, the potentiometer should be either cleaned or replaced.

In short words - it may be a faulty treble pot.

There are ways to disassemble and clean a potentiometer, but the difficulty of this task may vary and depends mostly on the type and build of the pot.

The other alternative is to have it replaced.

regards

Triarcuate

If you have the old pots look on the edge of the cans (metal backs) for the code. Take them to a good electronics supplier and they can match them or measure the resistance from each outside pin with all pins free of interconnection. You will also need to know the audio tapers. The supplier should be able to tell from the codes.