Having 2 problems with my Quad preamp. Any ideas?

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Friedmett

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I finally put 4 preamp tubes in my Quad and hooked it up.

On channel 1 rhytm 1 the sound level goes up and down. I think it could be the preamp tube for v1 that is old and needs to be exchanged.

The switching is weird. I plug in the fu2 board. All channels light red on the Quad. One is selected and sound comes through but I have no way of knowing which one is selected.

The fu2 board works and lights up as it should when I select one of the switches.

Any ideas on what is going on?
 
Does yours have a switch on the back near the power inlet that lets you decide which kind of footswitch you are going to use? If so, make sure it is set to the correct option.

The only switching problem I have encountered was the system trying to turn on every channel/mode at the same time, and I fixed it by accidentally shorting two pins in the footswitch jack (I was trying to clean dust out of the jack with the screwdriver while it was turned on, and it arced). Mine is a MIDI quad with FU-2A.
 
The volume swells are most likely tube on its way out. The switching could be a dirty connector mine was acting weird a couple of months back and once I cleaned the connection with contact cleaner it was working perfect again. My quad uses the FU-2A .

Lok
 
I checked the symptoms to be clear about what the switching does.

With the power on the Quad no channels are selected. This is normal according to the manual.

When I then hit any of the switches everything lights up and what channel the sound is from I have no idea.

I think the v21 tube is bad and a replacement will take care of my first problem
 
You could try changing the GEQ in and out (setting all sliders all the way down) and alternate switching each one in and out of the respective channel circuits. That and altering lead masters should allow you to figure out which channel is making noise (if you want to know that).

Do you have a 1/4" switcher, or a shorted 1/4" plug you could put into the ext. switching jacks on the back (with the FU-2 disconnected)? That might help narrow down the problem.
 
The only switch is a ground switch and it is a non midi 1990 version wired for 220 voltage which is standard in Europe more at 230-240 these days.

As long as I can select a channel I am happy.

To alternative channel switch I am using a Wah pedal into the external channel of choice on the back. Just one standard cable into the left side and I can click the channel on. Eq I do manually and that works fine once channel is selected.

I have found an amp service who got Mesa preamp experience here in Denmark so it's going in for its first service ever I think in a few weeks from now.

Otherwise it sounds awesome as always. I am working on cash for a 295 poweramp as I got one on hold
 
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