Output form computer to board using USB works but the signal for input doesn't work

here's a link to the reset info-
DIGITECH RP 7 VALVE User Manual Harmony Interval Charts

are you going from the board to a 'mic' input, or a 'line input' on the Mac? you will need to attenuate the signal to a mic input. try reducing output from the board by 50% and reduce the input level on the Mac by 50%, and see if the distortion is lessened or eliminated. From there balance board output to Mac Input until you find what sounds good outta the Mac.

Sounds like the output cable from the 802 is not correctly pinned to your input on the computer. Fred is on the right track but you may need to take it a bit further.
It may also be helpful to use a Pro USB audio interface such as the Digigram UAX220v2 (line level version).
If you wish to use the computer's on board sound card consider an IHF/Pro interface that converts balanced audio to unbalanced , and the proper cables. Two 3-wire balanced 1/4-inch from the 802 to the left and right inputs of the interface (XLR Male), then RCA (Red and White) to a 1/8-inch TRS Plug cable onto the the computers audio input.
Henry Engineering's Matchbox HD comes to mind.
Good Luck.

I will answer this assuming you have connected the inputs and outputs of both the pedals AND the amplifier/guitar properly. Double-check your connections! ;)

Otherwise...Have you checked all the patch cables to make sure they're ALL working properly? That's usually the culprit in a situation like this, all other things being equal. Cables take the majority of abuse in your signal chain and also happen to be the weak link in the signal chain as well. It only takes one bad patch cable in a series to interrupt the signal.

I would take a pedal with perfectly functioning inputs and outputs and use it to test each cable yer using. If you verify all the cables are in fact working properly (and you are 100% certain everything is connected correctly), that indicates there might be an issue with the pedalboard's onboard electronics. At the most simple, the "From Guitar" or the "To Pedal" or the "To Amplifier Input" jack might be bad. One or more them, in fact, but it only takes one to entirely interrupt that signal chain. The loop section is less straight-forward in that if one of the loops has a bad input or output jack, that shouldn't affect the overall signal chain, nor the inclusion of the other pedals in said signal chain.

So, I think it's one of three things:

1. The pedals, guitar, or amplifier are not properly connected;
2. You have a bad patch cable;
3. Something has gone wrong with the electronics onboard the pedalboard, and this will probably require service.

Hope that helps.

Johnny

First of all it is important that the amplifier must work to produce the output with an input signal. So disconnect and check with an audio test signal on the input line and at the coupling capacitor to the input. If this is fine then the fault is only the connection and it is possible that the input line has shorted and so the input is not acting. But if other inputs are working the connectors must be rewired and soldered once again without any bridging.

There are a number of configurations for a mixer like the 1832, the most common are PA system and Recording system. There are Main output jacks which carry the mix as summed in the main faders. These in a PA system would feed the pa amplifiers which drive the house speaker system for the audience. These connectors are XLR 3 pin type on the rear, intended for professional pa amplifiers which use balanced +4dbv line input level. Amplifier which have 3 pin XLR connectors for input signals can accept that high level signal. For home style HiFi amplifiers, the signal level is nominally -10DBv and balanced or unbalanced signal lines with 1/4in diameter phone plugs which are connected to the mixer by way of a second set of Main output connectors which are 1/4in phone jacks. Use whichever amplifier input level your amp has.
If you are not using it as a main PA house mixer, but using it for recording, the main output connectors go to a 2 channel recorder or computer sound card recorder. The power amp and your monitor speakers are connected to the connectors labeled "Control Room" (CTRL Rm). These output are useful for recording because the signal through the mixer can be monitored from several buses, Solo, main mix, selected by buttons provided. The buttons only affect the signal heard through the control room monitors, and not the main output which only sees the main mix so selecting "solo" does not interrupt the signal going to the recorder while the engineer in the control can be checking other signal paths through the board.

use the audio output to send the keyboards internal patch sounds, or use a usb midi adapter to use the keyboard to trigger the garageband midi sounds, if the keyboard has a midi output, that is. the usb output requires software drivers to use, and IS NOT mac compatible. You may have to select a midi source in garage band preferences or settings if you are using midi.

Since this has no audio output it will depend upon your computer to generate the sound using the audio system in the computer. You will need the driver software for the M-Audio to talk to the sound hardware in your computer and configure that to accept the MIDI inout from the M-Audio.
You will need to OPEN the volume and mixer controls for your sound board, unmute it, and enable the SYNTH channel and select "general MIDI".
As a test, download VanBascoe's Karaoke thing and play MIDI files to make sure your synth software is working. Then assign the MIDI source to teh USB input from the M-Audio.

If your CD player works hooked up to the DJ board, then try hooking the line out of the board into a auxiliary in or line in in or record in on your receiver using the appropriate cables.Try the CD in first and if there is too much signal then use the CD/Tape in. You need to match the output signal of your board to the input signal of your amp. Hope this helps.

Check all the capacitors one at a time for leakage.You might also have a transistor in the preamp stage which is starting to go bad. Whatever you do though don't use the speaker output jacks of the organ as line outs into the input jack of the guitar amp. In a properly working organ you could destroy the output transformer and the input stage of your amp because most speaker outs are A.C. voltage to drive the speakers not low level D.C. which is what your amp is used to. Let me know how you make out.