So I have an expensive Marshall 1/2 stack that just doesn't seem to work anymore, it worked great (little static), then next time I turned it on, nothing. It's about 15 years old but was only used the first 3 years. I looked at amp board and it looks fine and all leads seemed to trace fine (continuity) and no burn marks. So I need to use my home receiver for a while, though I don't really like this.

I guess I need to use the phono connection on this as the other connections are very low level inputs. I know I've done this before with my home receiver (Onkyo 2 channel amp, well 4 channel, speakers A/B & both play at once) and it worked but I had problems with sound level and static.

What I'm wondering is the best way to do this. The standard cord from the guitar has 2 conductors and the 1/4" plug has the + & - connection from what I remember. I'm trying to figure out the best method of making a cord or connection for this setup as I could use a standard guitar patch cable (which seem to fail at an alarming rate), or I thought about using RG6 (or some other cable TV coaxial cable) and on the end I would place a standard male compression fitting. From there I have screw on connectors Female onto the RG6 make connector, and male RCA connector. From there I could use an RCA mono-Y splitter (1 female in to 2 male outs) to connect to the Phono input on the receiver.

What I don't know if how this resistance in the RG6 will effect this setup and if there is a better method for doing this, maybe with shilded Cat6 or something, using 4 strands for each channel?

 

Don't use TV cable. Get some good quality mic cable.
And the phono input may not really be the best input but is should work It depends if it is a magnetic or ceramic input They are quite different. Do you have a microphone input on the Onkyo amp?
Te best thing is to get the Marshall amp fixed.
Posting pictures of what you are trying to do will be a good idea.

 

There are several websites that provide free schematic drawings of guitar amplifiers, and that is useful for trying to discover where a problem is located.
And remember that usually a burned up part was not what failed first! Something else failed and overloaded the burned up part.
AND, using any kind of cable TV coaxial cable for audio connections that may eventually be moved is certain to cause failures. So please do get some durable shielded audio cable. And learn how to solder well, which takes practice. Also, know that the reason that RCA phono jacks and plugs are used so much is that they are cheap. Quality or durability is not part of the reason.

 

There are several websites that provide free schematic drawings of guitar amplifiers, and that is useful for trying to discover where a problem is located.
And remember that usually a burned up part was not what failed first! Something else failed and overloaded the burned up part.
AND, using any kind of cable TV coaxial cable for audio connections that may eventually be moved is certain to cause failures. So please do get some durable shielded audio cable. And learn how to solder well, which takes practice. Also, know that the reason that RCA phono jacks and plugs are used so much is that they are cheap. Quality or durability is not part of the reason.

Thanks to both of you for your suggestions.

I have a lot of experience soldering and cut my teeth on modding the original play station with chips, from version 3 those solder points were so incredibly small it was almost impossible. I probably have almost a couple hundred hours soldering experience, so I'm ot too worried about that part.

Now I have some 25ft very expensive shielded car stereo audio cables (R & L), so 2 wires with 4 conductors and a remote turn on lead running down the middle.

Would it be better to use a single cable and then split it at the receiver into 2 channels or should I remove the male RCA connection on one end and then solder on a good 1/4" plug? Now that I think about it, is there more than 2 conductors in some guitar patch cables?

As far as using mic cable, IDK about that as I'd have to buy that and I'd rather not if it can be helped. I don't use this a lot so it is more for when I get the urge to play. Also, I don't move around while playing, I site on a stool/chair, so it's not going to be tweaking the connection on the back of the receiver and even on the guitar.

Is there anything that the remote turn on wire could be used for like for a ground or something to eliminate any buzz somehow?

Oh, BTW, this is for an electric guitar and an acoustic with an electric pickup, IDK if that makes any difference.

 

The reason that I suggested getting actual guitar connecting cable is that it seems to get a lot of flexing, and the cables made for most stereo installations are only designed to be flexed a bit during installation. So really it really is a reliability issue. If you are practicing or just playing for fun and it does not matter if the cable quits in the middle of a piece, then the stereo connection cable will be fine. But if you are playing for a crowd that paid to hear you that is a different situation.
Regular guitar cords have a good shield and just one conductor, super premium ones have two wires under a single shield, one is the signal and the second is the signal return , and the shield is tied to the"ground" side at both ends.
Digital guitar cords are different.
So if you choose to use the expensive shielded car audio cable, it should work fairly well. Tie the signal wire in each pair to the tip of the 1/4 inch guitar plug, tie the other wire of the pair into the return line, and connect the phono plugs at your amp, signal wire to pin, signal return and shields to the phono connector shell. Leave that power wire alone for the present.