Why are there two jack input connection in the back in the Laney RB 410 speaker cabinet?

Watch your impedance, when you add speakers the impedance will change. example 8 ohm speaker placed in parallel with another 8 ohm speaker the impedance is 4 ohms, placed in series the it is 16 ohm Me I would place in parallel this mixer should handle 3 ohms

On the back of your 6505 there are two jacks that are labeled speaker outputs. For mono function, use either one of those outputs and run a SPEAKER cable from your amp to one of the input jacks of your 1960a cabinet. I assume it is a 4X12 cabinet. Either input will work. Make sure you match the ohm selector on your 6505 (right next to the output jack, 4/8/or 16 ohms) to the ohm rating on your 1960 cabinet. It is likely labeled on the plate that houses the input jacks. You should be good to go. NOTE: Never turn your amp on unless it is hooked up to a speaker cabinet and never use instrument cable to hook your amp to your speaker cabinet. Bad for a nice tube amp like yours.
Rock on and hope it helps.

The jacks have to be replaced. If you are not adept at repair, best to take it to a shop for the repair. Do NOT use the unit till repaired. If the jack shorts you may damage your amplifier.

Most schematics won't even have any colors listed... so let us have you try this:

Find a system ground someplace like the sleeve of a 1/4 inch jack... Using an ohmmeter check for continuity to the available wires that are disconnected. ASSUME that those showing a low resistance will go to the "-" terminals of the drivers. If you have say a black and red... expect that the black will be one of the grounds... often the red then will be the (+) of the woofer. If you have whites and yellow... OFten the white will also have continuity to ground and be the (-) for the tweeter and the yellow then to the (+). Now since your speaker has 4 woofers we need to be careful to wire then correctly to get the 4 ohm impedance of the cab. IF each woofer is 4 ohms impedance, then we need to wire them in series-parallel. The shell of input 1.4 inch jack will likely go to black wires... two of the speakers will have their (-) terminals connected to these. The tip of the 1/4 inch jack will probably connect to one or more red wires. These will connect to the (+) terminals of the OTHER TWO woofers. Next one of the available (-) with no connections will tie to the (+) terminal of one of the first two woofers. SImilarly the remaining (-) terminal of one of the woofers will tie to the last (+) terminal that is vacant. Note the + of the horn will tie probably to the High level pot and this will tie to the crossover someway.
Here is a site with general schematics.

http://www.bcae1.com/spkrmlti.htm

OFTEN Roland has the opposite sense of normally closed contacts versus normally open. Test the switch with any continuity tester or an ohmmeter to see that the contacts work and come out to the switch. ALSO some amps require a TRS type connection (three wire plug) and others do not. From the schematic it appears that the Laney may REQUIRE a normally closed contact. There is also a pull switch involved that you MAY have to change the state of for operation of the pedal.

Here is the scheamtic for your amp:

http://elektrotanya.com/laney_aor100h_sch.jpg/download.html

Scroll down to the link at the page "Get Manual" and click to download. It is a JPG type file.

In case you don't have one, here is a link to the manual:http://www.peavey.com/assets/literature/manuals/80300573.pdf I don't know if you are using a separate crossover between the mixer and the amp but here is the simplest explanation.I just reread your question and I don't even know whether you have a Peavey amp. Run proper cables from the main output of your mixer to the main inputs of your power amp.They will be 1/4"shielded cables or Balanced XLR cables. Do not use unshielded speaker cables to hook the mixer and the amp together.Run speaker cables from the speaker outputs of the amp to the input jacks of your speakers.Make sure the impedance of your speaker cabinets equals or exceeds the impedance rating marked on your amp. Here is the link to the newer model PV2600 manual:http://www.sweetwater.com/store/media/pv2600_doc_manual.pdf Don't use Speakon cables unless your speaker cabinets are equipped with Speakon input jacks. Banana plugs aren't as solid a connection as the binding posts are.

Use a SPEAKER RATED cable which will have good quality 1/4 inch jacks. Go from a speaker out on the head to one of the jacks provided on the speaker cabinet. NOTE: some newer speaker cabinets use SPEAKON connectors and if those are provided, they are more secure than 1/4 inch plugs/jacks.

PLEASE loop the speaker cables through a handle of the cabinet at each end to avoid them being yanked out while hot as the amplifier can be damaged if it happens.

OBSERVE the maximum load. If the amp says 4 ohms minimum, put no more than two 8 ohm cabinets on the amp as two 8 ohms parallel to 4 ohms.

DO NOT use an instrument cable.

I just had this problem and wasn't able to find the solution on line, so, here 'tis.

Take off the six screws on top of the amp cabinet. Unplug the speaker plug from the amp jack.The metal amplifer box can now be pushed out of the back of the cabinet and the input jack remounted. I had to force the box a bit as it was glued in just enough to tack it into place. (I was afraid to force the electronics box out so I took the entire cabinet apart piece by piece until I could see there was nothing left holding it in.) I found that prying it this way and that with a butter knife helped crack the glue.

You can, however a bass speaker cabinet will NOT handle the higher pitch sounds needed for cymbals and snares, etc. You would connect it to the return AND doing so would DISABLE the other inputs of the bass speaker cabinet.

If you want both a guitar and drum machine into the cabinet, you need at least a small mixer or a speaker cabinet that can take two channels input simultaneously.

Plugging into the "return" of the cabinet DISCONNECTS the power amp from the preamp section in the cabinet.

Go to www.peavey.com/asstes/literature/specs/005584220_3.pdf. Apparently the 410 TVX can be used in 4ohm or ohm configurations just don't drop below 4 ohms and make sure your amp has the minimum required impedence. Hope this helps.