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*Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED
#28

the filter caps are set up temporary right now.
when i got the set, it had a single filter cap and a modified or repaired power supply (power resistors) end that i had to undo and redo to match the prints.

the set came with a single filter cap that was too big.

i downgraded from 450v 47uf to 160v 47uf dual filter caps.

the big bare sol bar is B+!!


the 6sq7 pin 6 220k ohm resistor is new and is actually 270k and twice the watts than original.. thats what i had.
the original resistor was reading 330k.

i guess i could hunt down a tad smaller than 220k? as long as i am 1w or bigger...? if the 270k is too big??

all other resistors are new excluding the parallel 2.2mg below the printt 6sq7 and the one 10mg pin 4 6sq7 and one 4700 on the 6sc7.



when i power up from a bone cold chassis, the set seems to play well enough until within a full minute the signal is disrupted by speaker crackle, pop, crackle pop.

anytime i power up afterwards there is speaker noise.

the pic above showes a "GREEN" resistor which is the 40ohm 5w power resistor on the AC hot line cord.,,,, this gets very hot, a bolt passes through the center and fixes the resistor against the metal chassis to wick heat,,, prior work shows someone used plastic insulators which tells me the heat cant easily get off the resistor. I temp'd in a 50ohm 50w made for free air and noise remains.

there are two resistors to the left which i had to reconfigure. the blue is 40ohm and the longer brown is 50ohm. i soldered them in parallel to make what reads now as 23ohms which becomes the single resistor for the pilot lamp, the output side of these two resistors feeds the filament string.

i am hopeful the socket is bad,,, measuring this here in a few.


as of right now though i have 3) 6sq7's which by the book says i have 3 bad tubes.
when i install all three,, the noise remains.
when i dongle / jumper wire bench test just the filament of the 6sq7 the problem **STILL** remains,,,, and hopefully what this really says is that i have a bad tube socket.


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RE: Minerva Tropic Master model w117 "EARLY" - by jcassity - 06-27-2018, 07:41 AM



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