Roadster Channel 4 Bass and Mid Tone Question

I just picked Up a used Roadster 100W head off Reverb.

Went through the channels to check if everything worked.

CHannel 4 the Bass and Mid Tone knobs do almost nothing. I mean I can barely hear any change in tone using either of them. I've tried with the treble up and down the presence up and down. I tried with different settings in multi watt and diode.

The 4th channel doesnt sound as loud as the 3rd channel either. I'm thinking possibly the tubes for that channel are bad. I hope its not someothing more.

My question, anyone with this amp can you tell me is this just how the channel is? is this normal? I love the other channels so far and i would hate to have to ship this thing back.

So I am trying to figure out a way to deal with this if there is a way to swap tubes for that channel to test it or something else I can try. Or is this something more serious. I contacted the seller havnt heard back yet. any advice please would be helpful as to what my course of action should be.

Howdy

Congrats on the amp anyway. My Roadster is pretty picky about where the knobs are so there can be something off in yours :|

The manual has a tube task chart where you can find which tubes are used in which channel https://mesa-boogie.imgix.net/media/User Manuals/Roadster_130613.pdf

I went through and just swapp3d each tube one by one and t3sted each time. Unfortunately this did not isolate.the problem or make any difference. So it looks a bit more serious than a simple tube replacement Unfortunately.

Off the top of my head I suppose both the bass and mid pots could have died seems unlikely they both died at the same time but possible.

Waiting to hear back from the seller he was cool about it and agreed testing the tubes was a good idea.

How high are you setting the gain? As you get farther past 3:00 the tone controls become almost useless.

Dom

Zero effect with gain on Zero thru 10

I found the problem it was a leaky cap. Cap #69 strangely enough.