Question about OG Mark IIC+ Effects Loop and built-in Reverb

[Genghis]

I had a tech friend helping me by doing some cleanup on my 1984 Mark IIC+. One of the issues was the reverb wasn’t working. I got a new tank and installed it. Still had some issues, so had him check it out. He found there was a bad connection and replaced three tubes that needed replaced. Everything is working great and sounding great.

I got the amp home and hooked it up with my AxeFX in 4cm and reverb didn’t do anything. He lives fairly close and came over to help figure out why it worked at his place and not at my place. It dawned on me to unplug the effects loop and strangely enough, that made the reverb work.

So, for any of you with older Mark amps, is this normal with these amps? Does using the effects loop cause reverb to not function?

 

[EOengineer]

That doesn’t sound right to me but I’ve never used a C+ loop. Shenanigans with IIB loop were a factor in the development of the C/C+ variants IIRC.

My Mark III doesn’t have that limitation. I will say I’ve never been impressed with the Mark reverb up until the V, so unless you know and love it, you’ll probably end up using outboard verb anyway. I get wanting to confirm the amp’s health though.

 

[Genghis]

Yeah, it is more of a curiosity. I tend to favor the AxeFX reverbs over built in, just checking to see if others have seen the same.

 

[laxu]

Digging up some IIC+ schematics, which I don't know how accurate they are, the reverb seems to be right before the fx loop so it should work just fine whichever you are using. It should be basically preamp -> reverb in, reverb out -> fx loop send -> fx loop return. If one or the other works, I wonder if something is wired wrong.

 

[Genghis]

Digging up some IIC+ schematics, which I don't know how accurate they are, the reverb seems to be right before the fx loop so it should work just fine whichever you are using. It should be basically preamp -> reverb in, reverb out -> fx loop send -> fx loop return. If one or the other works, I wonder if something is wired wrong.

Thanks. I figured it should work.