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Post by Rhythmark on Feb 4, 2018 11:36:35 GMT -7
Interesting where the loose bolt was With the amp on, put your finger on the transfer and chassis around it and see if you can actually feel the transformer vibrating. If it's noticeable, it will fail over time. That can happen when the insulating shellac between the transformation laminations start to crack and breakdown. When it does, you'll start to notice an actual mechanical "hum" coming from the transformer. I've seen one old Marshall where it was really loud...inducing the hum physically into the chassis at a pretty good volume. It one ground repair (loose nut) quieted it...I'd loosen and check them all plus any other jacks you may not have checked. ? Good job finding the mechanical issues! BradM where that bolt is is just under the chassis and I think its the output transformer- its big - in center. But yes the nut must have been loose and fell into the transformer. I got it out and later found the loose lug and put the nut on--! Ill feel the transformer later to see if there is any vibration. I think its fine now .. Im sure Doc just loves to hear about us digging around in his amps! --Thats why I love turret board and point to point wiring-- easier to work on!! And usually easier to diagnose-- Well hopefully this thread will help anyone down the road-- Check all the grounding points!!
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bradm
Junior Member
Posts: 74
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Post by bradm on Feb 4, 2018 22:45:40 GMT -7
I agree with turret board builds! I've been in enough Marshalls where I'm ever-so-gently removing pots and/or boards to replace just one component. I've come to enjoy jumping into Doc's builds. With some experience and a solid electronic background, it's not overly tough to troubleshoot. (Oh, inaudible oscillations can be a bear sometimes, but overall...nice amps to dive into.)
I do some one-off builds...no two the same. But, I do love my newly acquired Galaxie. Fun amp with all the features I need. And, so glad you found the major contributor to the problem!
Cheers! BradM
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