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Post subject: DRRI intensity button issues
Posted: Tue Aug 14, 2012 5:16 pm
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Hi,

I`m having a weird issue, when the intensity knob at 0 normal volume, when it's turned up the volume goes down. I bought amp used and never notice this issue....any ideas?

Denis


Last edited by Plourded on Wed Aug 15, 2012 3:46 pm, edited 1 time in total.

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Post subject: Re: DRRI intensity button
Posted: Tue Aug 14, 2012 6:15 pm
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Did some reseach and found this http://www.christianguitar.org/forums/t194751/

Looks similar to my problem, they mention op1 optoisolator is bad, what is the function of op1.

Denis


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Post subject: Re: DRRI intensity button
Posted: Tue Aug 14, 2012 7:03 pm
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OP1 is a dual-component assembly consisting of a neon lamp and a photo-electric transducer. One half of the tremolo tube is an variable-speed oscillator (rate determined by an RC network controlled by the front-panel "speed" control). These pulses are used to switch the neon lamp on and off. The emitted light from the lamp is detected by the photo eye which in turn gates the other half of the tremolo tube (a simple buffer/amplifier stage) on and off at the pre-determined rate. This creates the amplitude-modulated effect you hear.

A bad or marginal trem roach can cause the symptoms you describe but it also might be a bad tube at the V5 position. I'd try a tube swap before proceeding to more laborious troubleshooting steps.

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: DRRI intensity button
Posted: Wed Aug 15, 2012 2:12 am
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Thanks, I try changing tube same issue, I guess I will order a op1. Will let you know how i made out.

Thanks
Denis


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Post subject: Re: DRRI intensity button
Posted: Wed Aug 15, 2012 3:45 pm
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I need your help, is there some canadian website to order op1, I found some US one but shipping is triple the price of optoisolator.


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Post subject: Re: DRRI intensity button issues
Posted: Wed Aug 15, 2012 4:09 pm
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Have you checked to see if you actually have the opto or the newer circuit board version?

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Post subject: Re: DRRI intensity button issues
Posted: Wed Aug 15, 2012 4:15 pm
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mine was built 94-95,


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