Music Man HD Output Transformer

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CJ

Well-known member
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Jun 3, 2004
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customer brought in an amp, plugged it in,  output starts stinkin  and warm to the touch after 1 minute,

unplug and rip out

take home, pull apart,  see what gives,

runs four 6L6GC's at crazy voltages,



 

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boiler plate says Shumacher, (EIA code)

http://www.unclespot.com/transformerEIAcodes.html

must be based near LA,  shipping iron is expensive, buy local, like produce,
 

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break it down one time,  looks ok from the outside, no major heat problems, unlike SpaceX  missile,
 

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easy delam,  light epoxy (not varnish) 125 EI , two  lams this way, two lams that-a-way, 1 7/8" stack,
 

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those pieces of tape on the outside of the wind are called anchors, just a thin piece of tape wrapped around the turns becomes very strong, if you don't believe it, try wrapping two or three wires with a turn of scotch tape and try to rip them apart, that springy #20 wants to uncoil so anchors are important,
 

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wondering if we tore this thing apart for nothing, maybe there was a short and the transformer was fine, but no, finally some discoloration,  always the inner primary,

enamel stripped from wire due to heat, which means shorted turns, maybe about 20 or 30 on a few layers,

 

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and finally the former, we will rewind with a nylon bobbin because layered paper with #20 is a real PITA,
plus we better hi-pot from the first layer to the core,
 

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just show me the print, dang it!

ok, alright, cut me some slackage, workin OT on a holiday, wtf, over?  ;D

they crammed 1350 turns into 9 layers on the first primary, second section had 10 layers, so maybe the extra turns per inch rubbed that wire the wrong way leading to a general meltdown, maybe we will space that first section out into 10 layers for a minor upgrade and use a triple build insl.
 

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