Require schematic for Peavey XR600-B mixer section

It does not have built-in phantom power. Phantom power is a method used to provide power to condenser microphones and other devices that require a small amount of power to operate.
It is important to note that the XR-600B have XLR inputs which are typically used for condenser microphones that require phantom power but it does not provide this feature. If you want to use a condenser microphone with the XR-600B, you'll need an external phantom power supply or an audio interface that provides phantom power.

That is standard UK wiring.

Brown in Live.
Blue is Neutral / Return.
Green with Yellow stripe is Earth / Ground.

https://www.google.com/search?q=peavey+xr+1600d+wiring+diagram

Manual

https://peavey.com/manuals/80301359.pdf

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There should be a line in for the power amp section, though you may prefer to patch in prior to the eq section so you can equalise the system and the room.

If you connect the Main 1/4" out on the front to you HiFi aux input it should work. You will need to play with the volume controls to set the proper level so as not to overload the aux buss. The XR-600B manual is here-
Peavey XR 600B Operating Manual Page 4

Internal fuse. Or fuse near the speaker connections.

Remove power. Remove back cover look for
125v clear or ceramic fuse.

125V 5x20mm Fast-Acting Glass Fuse

I am guessing you have an older Peavey mixer amp. I believe these mostly used 8 amp fuses although older earlier ones may have used different. It should say on the back at the fuse holder. You can get these at Radio Shack, at better hardware store in either auto electrical or electric sections or on line.

plug the effects out into the input of your reverb/echo unit, plug the out put of the processor into an unused channel in the mixer, do NOT turn up the effects in that channel, to hear the effects in the main use the main level, to hear effects in the monitor use the monitor level. you must turn up the the effect send in the channel you want to hear the effects on and also the effects master.

That's easily done. Simply connect the left(or right) output of your mixer to one of the channels on the peavey. Use any line input. Since the peavey is a mono system, there's no need sending a stereo mix to it.

First off it's outputs to your speakers. If you had an extra set of powered or amplified speakers you could "Y" cable your speaker outputs. Your passive speakers won't work without an amp. You really need powered speakers or an amp for your extra speakers. (if you had powered/amp'd speakers you could run them off one of you "aux" out for monitors. Do not daisy chain your speakers connecting twi together, you'll change the resistance/ohms and damage your speakers. Trust me, I do this for a living.

Hi chillin884

Not a good sign. Something has gone wrong with the output stages of your Peavey. It is not a good idea to continue plugging it in as damage may occur to your speakers. I suggest you take it to a decent music gear repair guy for a look see and give you a quote to repair These heads, like all Peavey gear, are pretty solid and worth repair. Sorry to be the bearer of bad news like this, good luck

regards
Graeme