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Discussion Starter · #1 · (Edited)
Had some issues but resolved— some bad pots and the standby switch need replacing.

• I still need to know what kind of foot switch I need for this '72 YGM-3. Mine has two 1/4" sockets, one each for tremolo and reverb.

• tremolo ticking/knocking when engaged (I've tested it with another foot switch and there's no ticking when disengaged). Likely causes? I might have a tech make the intensity pot an on/off one, unless someone can point me to a diagram re how to make this.

Thanks.
 

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This video may help. I have tried some of this fellows suggestions and he seems to know his stuff. He uses a grid stopper resistor to resolve the tremolo ticking issue and explains how to do it at the beginning of the video.
 

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Nice work on the ticking fix in that video, but I better not ever hear anyone repeating that '2 grounds equals no grounds' nonsense. Ground loops are tough. He fixed it easily enough but has no grasp of how they work.
 

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Some of his mods are good ideas, but there conflicting mods. As an example his change to the bright cap is fine, but then he makes a coupling cap smaller which will tend to make the amp thinner sounding.
Also his changes to the input stage cathode resistors will do nothing to increase the gain. Those resistors are bypassed with a capacitor, so AC gain is set by that. All he's done is increase current through the tube.
He's correct there was a ground loop, but his explanation is bull. The source of the hum is probably the lack of capacitance in the power supply more than anything else. "Two grounds equals no ground" utter nonsense.
He might want to read a book or two before he works on any more amps.
Did he change the power cord and remove the death cap?
 
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