Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

*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.


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



Users browsing this thread: 4 Guest(s)
[-]
Recent Posts
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM
54C Complete Teardown/Rebuild
While I'm waiting to wrap up the final steps on my wife's Silvertone 2014, I started disassembly on the next project.  O...glyphmon — 11:07 PM
Preliminary work on wife's Silvertone 2014
Hello roy, that great news glad it worked out for you !! Sincerely Richardradiorich — 10:50 PM

[-]
Who's Online
There are currently 1380 online users. [Complete List]
» 2 Member(s) | 1378 Guest(s)
AvatarAvatar

>