B channel went out its the in put board where can I get parts

Very common situation, the main boards are all put together by robots and the small components are available to the manufacturers but not for general resale. Try an electronics store, im sure they would have what you are looking for. It may pay to take the board in. Some boards have the size / spec of the onboard parts written on the board.

Yep... failed channel... most likely "A" channel? There is weak insulation between two layers of conductors on the power amp circuit board that breaks down and blows out the switching transistors for that side... it is usually the rear-most amp. Repair of the board takes GREAT skill in restoring it as the burned area must be ground away and re-insulated and jumpers put in to replace the circuit that has to be removed. The blown components then have to be replaced. One can buy a new HCA2400 amp module for about $155, but delivery takes forever. Also please read my tip on Fixya regarding PMP Behinger powered mixers of a hazard when using Speakon to 1/4 inch speaker cables/adapters.

Yep! The power amp for that side has failed. There is a weakness of insulation in the multilayer board of some of these that causes the problem. If you haven't seen smoke, that is good. Depending on the revision level of the amp module, there will be two or three blown transistors and a Zener diode blown and possible arcing within layers of the board. The repair of the module takes great care and skill due to the arc damage which is internal on the multilayer board. The amp module is a HCA2400 and are rare costing about $160 and probably are out of stock at FullCompass.com which is the Behringer parts distributor... I have waited 3 months for simple parts... I had one HCA2400 shipped to me but they had wrapped it so tight in bubble wrap that capacitors were peeled off the board and it had to be returned. They didn't know when they would get more... If you have seen smoke, then two other small transistors and a metering resistor have blown. Worst case is when the power supply gets wiped out as well... that ups the parts ante to about $50 as two expensive IGBT's also fail and a half dozen other parts as well.

I have repaired three of the HCA2400 modules and it takes many hours with dental drill to carve out the burned cancer and then re-insulate and put jumpers where the circuit traces used to be. It is NOT DIY for sure. Replacing the transistors requires a desoldering station. I have one unit that a hacker tried using solder wick and destroyed the board.

Probably the channel A went. If you are fortunate, the power supply is still OK. There are protection circuits for the speakers, however you MUST use speakers that are rated at over 400 Watts. If you use smaller ones, they can get blown. There is a weakness primarily on insulation for channel A and an arc between layers of a circuit board can wipe out several transistors and a zener diode and sometimes a metering resistor. Once this happens, have unit serviced before using it again as further damage can result.
ALSO PLEASE read my tip I posted on FIXYA regarding a grounding hazard when using Speakon to 1/4 inch speaker cables... essentially the barrel of the 1/4 inch jack of the A channel is the hot lead, NOT the tip for that channel.

What happened was there was an arc between layers of the multi-layer circuit board in the HCA2400 power amp at the rear of the unit. It takes extensive labor to repair the board and $20 of parts.

If you replaced the fuse or if no lights come on, it likely took out the power supply too... that is about $30 of parts.

IF THE LIGHTS still come on, get a replacement HCA2400 module (includes heat sink) and replace it. They cost about $175 online.

I have repaired several of these, but it requires a lot of skill and time to repair the module as the burned area must be carved out and replaced with jumpers and several semiconductors have to be replaced and probably a metering resistor which is usual source of the smoke.

There are so many possibilities for connection it is not practical to try other than a very cursory explanation.

The first thing is WHAT channels (usually only microphones) do you want to have the compression on?

Then do you want the equalizer for all the output, or jsut parts of it. for all channels you cn take the outputs iof the board to the equalizer, and the output of the EQ to your power amps.
NOTE: all these interconnect should be balanced connecs either TRS or XLR cables.

For the compressor, you will probably select the mics into one of the SUB busses and send that to the compressor, then feed the output of the compressor back into the board on an auxilary channel input into the main mix...

For the mic channels you will NOT have the L-R button selected, but instead the desired Sub Buss.

Sending diagrams are near impossible on this system...

Check the possibility of marginal connectors.

You MIGHT try putting a small bit of CRC226 into the fader for that channel if it might be the fader. CRC226 is available in the electrical dept of Home Depot in a small spray can with a tube spout. DO NOT use De-Oxit in the faders. Put the tube into the slot and give a SMALL shot and work the slider. This MIGHT fix your problem. Other than that it is ready to go to the shop.

There is an internal f ailure and the unit will require servicing. To get by until you can get it fixed, you can get line transformers that will allow the mics to be used on the higher channels.

If you have inadvertently plugged a source into the :insert" jacks of these bad channels by mistake, that may have blown the input op-amps.

A lot of dis-assembly of the board must be done to get to the parts to repair.

Another possibility is if the sliders have gone bad... SAME prognosis for repair.

Unfortunately, this is not a problem that will be easily resolved remotely. As far as I know, the main module is not a replacement part. These units are pretty rugged and it sound more like you have a power supply problem rather than a board problem. If you have not worked on one of these before, please do not attempt to dis-assemble one. These are a bit tricky to work on. More than likely, the problem will be either in the power suppy, or be a couple of defective surface mounted op-amp ICs. None of the parts required should be expensive. Based upon your description, I would expect a parts cost in the $15-$30 range.

Where are you located? Perhaps I can recommend a service shop.

Dan

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