I also posted this in the General Support section, but I was hoping you guys might have some thoughts on this ...

I've had my Overtone for about a week. I bought a completely built unit with the head cabinet. Up until today it has been working wonderfully. Today I got a new speaker to use with it, so I carefully disconnected everything and gently moved the head so I could get at the cab. I switched the speaker and made sure my connections were all correct by testing the cab with another head first. I put my Overtone back in place and reconnected everything (speaker, power, effects loop and foot switch). I fire it up and -- No clean channel!

The Overdrive channel works and sounds great, but when I switch to the clean channel there is not a sound - its like the amp is in stand by. I tried turning the amp off and disconnecting the foot switch. Both switches on the back for boost and dirty channel are off. When I turn the amp on I get sound but its not the clean channel its the OD channel. When I flip the switch in the back to turn the OD channel on - dead silence again. Its like it thinks the OD channel is the first channel and when I tell it to go to the second, it has no where to go.

What gets me is that nothing has changed other than the speaker. The speaker works fine and I get this issue even with other cabinets / speakers. I mean I don't understand how this thing can survive a trip from Malaysia and work fine, but a trip to the couch and back breaks something?!?

Thanks in advance for any help you can give!

Regards,

Rich

Yah - I just emailed him. I'll keep you guys posted even if it turns out it was just me doing something stupid. I'm hoping that its just a simple setting type thing. The amp seems to be built very solidly. I just can't imagine something broke when I handled it so carefully. We'll if something does need to be fixed, better early in its life and not when moving it to do a gig - I guess.

Thanks mcinku! Those are the things Nik is suggesting too. You sound more technical than me! But my thinking was the same - how could the OD channel be working and not the clean? You'd think both wouldn't work.

I did swap out the V1 tube for a fresh new one that I know works with the same result. Unfortunately I don't have the equipment to read the plate voltage. Nik also suggested a potential short in the foot switch connectors or an issue with the relay. From the outside the foot switch socket looks good, but I think I'll have to take a peak inside and see if anything obvious jumps out. But anything much beyond that and I don't think I'll be able to do much. I can follow a schematic and have made stomp boxes, etc. but I'm no amp tech by far.

Any thoughts on how to check the relay?

I have my amplifier wired such that if the power is cut to the OD relay it stays in "OD mode" rather than clean. I suspect Niki wired the Overtone in the same manner. Therefore, it seems as if your amp is behaving as if you have lost power to the OD relay. Try searching for a loose solder connection at the switches at the back of the amp. Also check the power lines to the relay. See the photos of my amp, which is probably close to the Overtone.

ic-racer, Thank you! Much appreciation for the great information and detailed pics!!
I'm really hoping its something straight forward like a loose solder connection at the switches. I'm going to crack 'er open and let you know what I see. Thanks again!

There are certainly easier circuits to have your first attempt at trouble shooting with but keep at it.  Mcinku is right on.  If it's not a simple case of failed solder joint or bad valve then you have to start isolating to pinpoint the problem.  Do you have a DMM?  If not, it's time you had one anyway.  Be safe or she'll bite you.  If you're not confident with this adventure save it for a qualified tech.  I agree with the other guys that it sounds like a malfunction in the relay circuit so find a DMM and check back.

Thanks guys for all the advice and responses.


Yes - actually the PAB does work both with the foot switch and manually.


This might be a stupid question, but is DMM - digital multimeter? I don't have one, but I'll make a run to radio shack today. Is there a range on the multimeter that I need to look for 15, 17? It seems I need one to get to the next step of trouble sooting with Nik.

Nik is basically saying it should be stuck in clean mode not OD mode if any thing. And its most definitely in OD mode. The ratio and level knobs are active and they wouldn't be in clean mode. Nik said to look at a resistor and wire marked as b-6 (on the schematic) after the OD trimmer:
 
"In clean mode, this should be grounded. So basically, we will know if flipping the OD toggle switch to manual makes the thing to be grounded or not.  If the relay is faulty, ie not engaging, then this resistor is indeed is linked to the 0.05uf on board (from clean output) and thus, since this resistor is the input into OD, always be in OD mode."

I'm going to check this out, but also look for techs in the area. There's a good one about an hour away, but it seems to take forever for him to get to anything bc he's always swamped. I'm hoping I can help isolate the issue with the multimeter.

From everything I’m hearing this should be a pretty simple straight forward fix. I just don’t know enough about it and frankly I'm a bit nervous about tinkering in there, so I’m going to bring the amp to a tech tomorrow. Downside, he’s swamped, but he said he could get it done for me within a week.

I appreciate all your help and I’ll let you know what he says!