byassing Fx loop completely on this amp ?

[Ang3lus]

hey all,

before I do anything stupid, since I don't use fx loop at all (using slave out to a different amp with fx on it) I would like to remove the fx loop completely and possibly even remove the tube.

now, my idea was to run a wire from the junction of C1/R1 to C4 (where the anode of the tube is connected).

would this bypass the loop completely and I can remove the tube ?

reasons I want to remove the loop:

1. I never use it
2. the only way the amp will work with the fx loop is if I connect the fx send into return gnd ?!

[JMFahey]

Leave it, just don't use it, but you seem to have defective jacks, replace them.

[JazzGuitarGimp]

The jacks aren't defective. If I'm reading the OP correctly, he is using the efx send jack to pick off signal to another amp. The way the efx send / return jacks are wired, inserting a plug into either send or return jack will interrupt the signal to the power amp. You need to short pin 1 to pin 2 on the send jack to correct this.

[Ang3lus]

I'm running the amp normally, it just won't work without send tip connected to return gnd.

I've no idea why, but... is my method enough to bypass the fx loop completely ?

[pdf64]

the only way the amp will work with the fx loop is if I connect the fx send into return gnd

It's probably just a bad contact in the return jack socket switching mechanism
Sure you could totally eliminate the FX loop and removed the tube, but the gain of the amp after the channel master volumes may be affected.
So things may need a bit of tweaking.

[Ang3lus]

i replaced the jacks, still same issue, any idea what could cause it ?

maybe the relay that affects the loop is bad ?

[JazzGuitarGimp]

Ah, I misunderstood - sorry. You said you were using a "slave out", and from looking at the schematic, the only way to get a slave out from this amp is the efx send jack. My apologies.

But I don't understand what you mean when you say you "connect the fx send into return gnd" It seems to me when you ground a signal, it cuts completely out, no?

[Ang3lus]

I meant line out, sorry, hehe, my mistake

what o mean is, im connecting the fx snd switch into return gnd, thats the only way im getting volume, if i try to. connecr rhe fx snd switch to return tip, for an interrupt operation, im getting like a 2watt amp, volume is really low

[JazzGuitarGimp]

I meant line out, sorry, hehe, my mistake

what o mean is, im connecting the fx snd switch into return gnd, thats the only way im getting volume, if i try to. connecr rhe fx snd switch to return tip, for an interrupt operation, im getting like a 2watt amp, volume is really low

And when you do this, you have to plug a cable from the send jack to the return jack, yes?

[Ang3lus]

I will simplify it for my sake also.

Normal jacks, no switch inside.

using a jumper cable, low volume
no jumper cable, no sound.

using switched jacks.

connecting the switch to return gnd from fx send, full sound full volume NO CABLE connected between, connecting a cable makes no difference.

puzzeled by this

thanks all for your help

[JazzGuitarGimp]

I think I understand now - thanks for the explanation. And you are right, this is curious.

I think the first thing I would do is ring-out the send / return jacks with an ohmmeter to make sure the jacks are pinned-out the way you think they are. Easiest way to do this is to plug a guitar cable into each jack, one at a time and with nothing connected to the other end of the cable, use an ohmmeter to confirm that the solder lug on the jack which you believe to be the tip connection is in fact the tip connection. Then make sure the solder lug you believe to be the sleeve (gnd) connection is also correct. Assuming there is only one more solder lug on the jack (which should measure open circuit to both tip and sleeve), that lug is the switch connection.

Question, with the wiring done as you describe (so that it works with full volume), is the signal interrupted when you plug a cable into only the return jack?

[Ang3lus]

when it was fine, after i first built the amp, yes, the pre amp section went silent when plugging into return and vica versa

replaced jacks with cliff jacks and also tried switchcraft jacks, same problem, replaced shilded wire with normal wire and still the same problem, so curious as to what it could be

[pdf64]

If the signal is grounded then it will be totally muted = off.
Something else must be happening.
Maybe you are getting mixed up with the jack socket terminals?
eg I've known suppliers to confuse stereo and switched mono jack sockets.
Given that your findings can't be the real situation, the functionality of everything needs to be verified, as described previously.