Fender "the Twin" bypassing fx loop jacks...?

[SCStowaway]

So it looks like some of these jacks might be the source of some of the issues I've been having. Im wondering if anyone has some insight on just removing them all together. Ill never use them, so Id rather not replace them if I didn't have to. Thanks!

[Pedro Vecino]

The Twin red knob (although there is some identical version with black knobs), I imagine.
If you don't use it, the only connection that can fail is the one that exists internally inside the "power amp in" jack. If the jacks are functional, you can insert a small jack-jack cable. You could also bridge these two points:

[SCStowaway]

ok cool, ill look into that. Thank you for the pic, very helpful. Another thing I forgot to mention in the first post was about bypassing the fx loop db three position switch. I had been having volume fluctuation issues, and the other day while wiggling things, checking for bad connections, just touching the switch gave very similar results. I will never use the fx loop, nor the "power amp thru." Was hoping the was a somewhat easy way to just get rid of the circuit, jacks and switch

[Pedro Vecino]

In my book "How to disable an amplifier" I explain it
One possibility is bridge those contacts and set the selector to the "low" position.

[Chuck H]

I was looking at this schematic and it seems that it would be very easy to bypass the whole in/out circuit and it's associated level switch. In the attachment I've shown where the circuit could be broken in two places and a jumper installed. You may need to adjust the resistor values for the R158/R110 voltage divider to get the same exact gain level as before the mod. Once circuit is isolated and the jumper is in place you could literally unplug V3 since it's no longer in the circuit. This mod comes with the caveat that it will invert signal phase since the in/out recovery triode (that flipped the phase) is no longer in the signal path.

[SCStowaway]

very interesting!! That sounds like something id be very interested in doing. Cause that 3 position gain switch makes a lot of noise when jiggled.

[Jquijano]

I have a similar problem. Just noticed that if i leave the effercts loop in the middle i gef more output from the amp. Could the mono jack be broken?

[sparkies]

I have a similar problem. Just noticed that if i leave the effercts loop in the middle i gef more output from the amp. Could the mono jack be broken?

I would think it would be an issue with the 'power amp input' jack

[g1]

From what I remember, it is normal for these amps to have a slight volume change if you change switch settings when loop jacks are NOT being used.

[Chuck H]

The old CD-60/120 amps from Dean Markley had level adjustable/unity gain effects loops. Everyone complained and the average guitar player was utterly confused and never able to get the amps to work right. These were the JMF-Spectra amps that sounded really good and now enjoy a cult following. When he reissued those amps I told him to ditch that effects loop for a simpler in line circuit and he did.

If you're a guitar player dealing with one of these unity gain effects loops just take a half hour and do some web searhing on the subject. They work fine but you have to know how to set them.