Hello. When I use the channel switching with a pedal on my Mark iic+ it works as it is supposed to, but after a while it gets stuck on the distortion channel and it doesn't switch anymore. Do you have any idea what may be the cause? Thank you.
Channel switching stuck on distortion in Mark iic+
- Thread starter jhhi
- Start date
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Except Mark IIC+ has no switching relay, but vactrol LDR instead...
First I'd consider checking if the Lead Drive knob is pulled or pushed. If it is pulled, it is normal that the amp is stucked on the lead channel, whether you activate the footswitch or not. In order to be able to footswitch between clean and lead channel, the Lead Drive knob has to be pushed.
After this verification, you can try to plug another footswitch in order to see if your previous footswitch is faulty.
Then, if all this don't solve your problem, you can consider taking your amp to a tech. There could be a failure in the switching circuit inside the amp.
First I'd consider checking if the Lead Drive knob is pulled or pushed. If it is pulled, it is normal that the amp is stucked on the lead channel, whether you activate the footswitch or not. In order to be able to footswitch between clean and lead channel, the Lead Drive knob has to be pushed.
After this verification, you can try to plug another footswitch in order to see if your previous footswitch is faulty.
Then, if all this don't solve your problem, you can consider taking your amp to a tech. There could be a failure in the switching circuit inside the amp.
Except he says it works normally till it runs for a while,so it is probably heat related,bad LDR.Rather than using a mechanical relay they use these LDR's,so just to avoid explaining what an LDR is,I used the "relay",if the OP is capable of changing either a relay or LDR,he would know what I was talking about.
Oops, I feel deeply sorry if I've hurt your feelings... :roll:
That being said, I don't feel like it could be a faulty LDR: a broken LDR would have infinite resistance which could cause the amp to be stucked on the clean channel instead of the lead channel. If the amp is stucked on the lead channel, the LDR have to be "on" all the time. So that would rather point to a problem on the rest of the switching circuit, as I mentionned earlier.
But, before considering this kind of failure, the OP would rather ckeck first the two other possibilities snorkel54 and I have listed, which are well easier to diagnose and solve.
That being said, I don't feel like it could be a faulty LDR: a broken LDR would have infinite resistance which could cause the amp to be stucked on the clean channel instead of the lead channel. If the amp is stucked on the lead channel, the LDR have to be "on" all the time. So that would rather point to a problem on the rest of the switching circuit, as I mentionned earlier.
But, before considering this kind of failure, the OP would rather ckeck first the two other possibilities snorkel54 and I have listed, which are well easier to diagnose and solve.
Hurt feelings?Nah,I aint 14 no more.An LDR is incapable of "infinite resistance",that is one of the drawbacks of these switching schemes.One failure mode is the resistance begins to lessen,allowing some signal to leak thru.The fact that he says it works normally "for a while" is more indicative of something besides the switch.
Funny to see how picky you are when I simplify "off" LDR as "infinite resistance" while you were grossly assimilating LDR as relay. Anyway... 
:lol:
The fact that the OP says it works normally "for a while" and then it went wrong rather suggests me that we, as musicians, can be caught in the momentum while playing and forget that we had pushed or pulled a knob, that had defeated the same function on the footswitch board.
That is why I suggested checking first the simple things. :wink:
But I am afraid that all this debate is useless as we may have no feedback from jhhi, according to his low-count posts. :roll:
:lol: The fact that the OP says it works normally "for a while" and then it went wrong rather suggests me that we, as musicians, can be caught in the momentum while playing and forget that we had pushed or pulled a knob, that had defeated the same function on the footswitch board.
That is why I suggested checking first the simple things. :wink:
But I am afraid that all this debate is useless as we may have no feedback from jhhi, according to his low-count posts. :roll:
"But I am afraid that all this debate is useless as we may have no feedback from jhhi, according to his low-count posts".
Are you here to help the guy,or start a pissing match?Why would he respond.Yes,I referred to the LDR as a relay,quite common here in the USA,as they perform the same function,an electronically controlled switch.I have been repairing amps for over 30 years and have had hundreds of Boogie amps on my bench,not all for switching problems,but all but one that had a switching problem was caused by a failed LDR.The one that wasnt LDR caused,was a broken wire in the switch pedal.An intermittent switch would not consistently turn on at start up and stop working when it was warmed up,it would work "intermittently" after warm up.Truth is,nobody can be sure via a forum like this what is wrong with an amp without having it on the bench,we make suggestions based on our experiences.Your responses indicate that your experiences are engaging in pissing matches on harmony central,from a basement somewhere in europe.
Are you here to help the guy,or start a pissing match?Why would he respond.Yes,I referred to the LDR as a relay,quite common here in the USA,as they perform the same function,an electronically controlled switch.I have been repairing amps for over 30 years and have had hundreds of Boogie amps on my bench,not all for switching problems,but all but one that had a switching problem was caused by a failed LDR.The one that wasnt LDR caused,was a broken wire in the switch pedal.An intermittent switch would not consistently turn on at start up and stop working when it was warmed up,it would work "intermittently" after warm up.Truth is,nobody can be sure via a forum like this what is wrong with an amp without having it on the bench,we make suggestions based on our experiences.Your responses indicate that your experiences are engaging in pissing matches on harmony central,from a basement somewhere in europe.
McBarry
Well-known member
Not to throw too much of a spanner on the works.. but I'm wondering about a thermal problem aka dry joint opening up under cumulative heat.
And 1000% agree with Stokes that no-ones really gonna know into it's benched and a methodical sequential approach is applied..
Would love to hear the outcome though..
And 1000% agree with Stokes that no-ones really gonna know into it's benched and a methodical sequential approach is applied..
Would love to hear the outcome though..
Me too, David. :wink:
And I also agree that none of us owns a crystal ball, so it's difficult to diagnose a problem via internet.
It's precisely why I was waiting for an answer from the OP. It is not only a methodical sequential approach but also an iterative process.
That, and also a matter of courtesy. I hope it still is a moral value shared all over the world, not just in Old Europe...
That being said, your diagnosis may be right, Stokes. I was just suggesting a simple verification because I've just experienced something similar. Few days ago, somebody brought me a Fryette SigX which was supposed to have shown signs of weakness after 2 hours of rehearsal. It turned out that the bypass of the effect loop, in series mode, has been accidentaly disengaged, and as the loop level was set very low, the amp sounded weak. After checking the guts and the voltages, nothing was wrong, and the amp was good to go.
(Stokes, I wouldn't respond to your assumptions about me, willing to start a pissing match. I would just be grateful if you avoid to compare me as a 14 years old teenager quarrelling all over the internet. Although you might not give a **** of my opinion about you, I sincerely think you are an excellent amp doctor, as attested by your valuable posts all over this board. Please, continue to behave like an adult as somebody expresses a different opinion from yours or points out your own contradiction.)
And I also agree that none of us owns a crystal ball, so it's difficult to diagnose a problem via internet.
It's precisely why I was waiting for an answer from the OP. It is not only a methodical sequential approach but also an iterative process.
That, and also a matter of courtesy. I hope it still is a moral value shared all over the world, not just in Old Europe...
To be clear, i wasn't suggesting an intermittent switch failure. Please, go back to my posts that dealt about the interaction between the push/pull lead drive knob and the footswitch.stokes said:
That being said, your diagnosis may be right, Stokes. I was just suggesting a simple verification because I've just experienced something similar. Few days ago, somebody brought me a Fryette SigX which was supposed to have shown signs of weakness after 2 hours of rehearsal. It turned out that the bypass of the effect loop, in series mode, has been accidentaly disengaged, and as the loop level was set very low, the amp sounded weak. After checking the guts and the voltages, nothing was wrong, and the amp was good to go.
(Stokes, I wouldn't respond to your assumptions about me, willing to start a pissing match. I would just be grateful if you avoid to compare me as a 14 years old teenager quarrelling all over the internet. Although you might not give a **** of my opinion about you, I sincerely think you are an excellent amp doctor, as attested by your valuable posts all over this board. Please, continue to behave like an adult as somebody expresses a different opinion from yours or points out your own contradiction.)
Happend to one off mine as well. I had one with an in line resistor and another without. The one with the resistor in line failed. Left resistor in and used a jumper wire around it. Has not failed since. Check the one wire coming off foot switch jack to board. For some reason this one had a shield resistor. Maybe yours does as well. Just alligator clip a jump and test switching..
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