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

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RE: Minerva Tropic Master model w117 "EARLY" - jcassity - 06-30-2018

here is the inventory of oldradioparts.com on octal's
which line item number do i need to buy/?

Item# PN / DESC
1030-612 **** 8 PIN OCTAL SOCKETS **** 0 0.00
1030-615 0 0.00
1030-617 AMPHENOL 8P 8P, BLK/TAN, W/MTG PLATE,USED 11 1.05
1030-618 AMPHENOL 8P 8P, BLK/TAN, W/MTG PLATE, NEW 8 2.75
1030-619 AMPHENOL 8P 8P, BLK/TAN, W/WAVY WASHER, U 21 0.90
1030-620 AMPHENOL 8P 8P, BLK/TAN, W/WAVY WASHER, N 12 2.15
1030-627 AMPHENOL BLK ETHYLON, NO PLATE,MTG IN BOOT 17 1.25
1030-629 AMPHENOL BLK ABOVE: FOR BOOT SEE HARDWARE. 16 0.00
1030-631 AMPHENOL 8P AMPHENOL TYPE BUT NO GROOVE.. 15 2.40
1030-631 ABOVE, MAKE > TUBE BASE ADAPTERS, 1 1/32 id 0 0.00
1030-635 OCTAL WAFER 8P,BROWN WAFER,1 1/2" MTG,NEW 6 1.75
1030-636 OCTAL WAFER 8P,BROWN WAFER,1 1/2" MTG,USD 7 0.50
1030-637 OCTAL WAFER 8P,BROWN WAFER,1 5/16" MTG, N 5 1.75
1030-638 OCTAL WAFER 8P,BROWN WAFER,1 5/16" MTG, N 10 0.50
1030-639 OCTAL WAFER 8P, BROWN WAFER,MISC USED,INQ 10 0.00
1030-641 OCTAL M-I-P 8P M-I-P, 1 1/2 MTG, TAN, NEW 17 2.00
1030-642 OCTAL M-I-P 8P M-I-P, 1 1/2 MTG, BLK, NEW 4 2.00
1030-644 OCTAL M-I-P 8P M-I-P, 1 5/16 MTG, BLK,NEW 25 1.75
1030-646 OCTAL M-I-P 8P M-I-P, VARIOUS USED, INQ.. 21 0.75
1030-648 OCTAL SADDLE ABOVE PANEL, 1 5/16 SPC, INQ. 0 0.00
1030-649 OCTAL SADDLE ABOVE PANEL, 1 1/2 SPC, INQ. 0 0.00
1030-650 OCTAL SADDLE BELOW PANEL,1 5/16 SPC, NEW.. 12 2.00
1030-651 OCTAL SADDLE BELOW PANEL,1 1/2 SPC, NEW.. 35 1.65
1030-652 OCTAL SADDLE 8P SADDLE, VARIOUS USED, INQ. 20 0.35
1030-654 OCTAL WAFER 8P WAFFER-MTL PLATE, 1 1/2, N 17 1.40
1030-655 OCTAL WAFER 8P WAFFER-MTL PLATE, 1 5/16,N 0 0.00
1030-657 OCTAL PORC. 8P PORC REC,SADDLE MTG 1.5",U 5 1.15
1030-658 OCTAL PORC. 8P PORC REC,SADDLE MTG 1.5",N 2 2.75
1030-659 AMPHENOL PORC 8P PORC REC, W/WAVY WASHER, U 10 1.00
1030-660 AMPHENOL PORC 8P PORC REC, W/WAVY WASHER, N 9 2.50
1030-663 AMPHENOL PORC 8P, PORC REC, W/MTG PLATE,USD 9 1.15
1030-664 AMPHENOL PORC 8P, PORC REC, W/MTG PLATE,NEW 2 3.00
1030-665 NATIONL CIR8E 8P, SAME AS ABOVE W/SLOTTED H 3 2.50
1030-667 OCTAL PORC. 8P, PORC TRANSMITTING - USED. 5 2.00
1030-668 OCTAL PORC. 8P, PORC TRANSMITTING - NEW. 15 4.00
1030-669 AMPHENOL 8PIN AMPHENOL TYPE BUT NO GROOVE.. 15 2.50
1030-669 ABOVE,TO MAKE TUBE BASE ADAPTERS, 1 1/32 id 0 0.00
1030-670 OCTAL RELAY 8P, TERMINAL SCREWS, INQUIRE. 2 0.00
1030-671 NATIONAL XC-8 8P, PORC, REC, 1 1/2", NEW... 4 3.00
1030-672 NATIONAL XC-8 8P, PORC, REC, 1 1/2", USED.. 5 1.25
1030-673 NATIONAL CIR8 8P, PORC, W/MOUNTING PLATE, N 1 3.00
1030-674 8P PC BOARD 8P, PRINTED CIRCUIT, INQUIRE. 14 2.00
1030-675 OCTAL PLUG AMPHENOL TYPE, 8P MALE, NEW. 7 2.65
1030-676 OCTAL PLUG AMPHENOL TYPE, 8P MALE, USED. 2 0.90
1030-677 OCTAL PLUG WAFER PLUG, SEE HARDWARE #438 0 0.00
1030-678 OCTAL SPEAKER SPK PLUGS, OCTAL, INQUIRE.... 6 2.40
1030-679 OCTAL BASE GT, BKLT, NO PINS ON 4 & 6, N 20 0.45
1030-681 HOLE PLUG BLACK PLASTIC, FOR 1 1/8 HOLE 15 0.85
1030-682 OCTAL KEYWAY REPL FOR BROKEN OCTAL KEYWAY, 8 1.75
1030-684 AMPHEN SHELLS SEE #1030-439 AMPHENOL COVERS 0 0.00
1030-685 ADAPTERS 8-8 OCTAL TO OCTAL ADAPTERS, INQ. 0 0.00
1030-686 ADAPTERS 8-8 8 FEMALE TO 8M W/BKLT SHELL 4 0.00
1030-689 ------------- ----------------------------- 0 0.00

RE: Minerva Tropic Master model w117 "early" ****SOLVED - jcassity - 07-01-2018

Radio is up and running, i found the real cause and problem.

It was not the socket on the 6sq7,, it was something more in line with the types of problems i generally have which are exceptionally strange and odd while being valid and not caused by any of my doing.

funny thing is the fix only takes about 1 tenth of a second to perform.

will update tomorrow with pics of how i isolated and nailed down the cause.

i was very skeptical about the socket being bad because after closer examination,,, they are pretty much bullet proof.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - EdHolland - 07-01-2018

Oh, you can't leave us hanging like that!  Icon_e_surprised

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - David - 07-02-2018

So what was the problem, we need to know!!!!!

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-02-2018

i decided to verify if the socket was bad or not,,, and it was not.

i extracted the pin out of the socket that ties to pin 6 of the 6sq7.
i soldered the pin to a foot long wire.
I slipped the clip part of the pin onto the base of this tube pin 6.

on the other end of the jumper i tied the 220kohm R and the .01 uf cap and the tone control lead all together on the other end of my jumper wire.
this allows me to be able to plug in the tiube and have pin 6 function in the game but i am wrapping around/ bypassing the socket.

while i was at it, i started addressing the wattage on the 40 ohm power resistor , and thats whats going on to the right of the set on the bench.
see picture.

other stuff happening off to the left is where i took off the IF cans to inspect for problems... hence a small white jumper wire to maintain a certain ground reference.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-02-2018

i powered up and the problem remained.
so jumping around the socket proved out a socket is a waste of time.

The only conductor i had not disconnected from pin 6 was the tone control shielded wire run.

i took that wire away from my gobbled 3way splice with the read jumper and the radio was perfect, no poping or anything.


at that moment  i traced that shielded wire out and confirmed it was the tone control,, a part of me said,,, who needs tone control anyway.
i put everything back to normal and did not connect the tone control back up..
Radio operates fine,, and pin 6 on the 6sq7 reads 60VDC!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

so,, the center of the radio has three shielded wire runs which on each end the shield has been skinned back an inch or so and soldered to the chassis.
the wire pokes out and continues on out to its final termination point.
i guess the insulation around the conductor is breaking down and its arch flashing out onto the shield... pulling down my pin 6 voltage expectations.

I ran a plain old wire from the tone ctl to pin 6 and all is well.

here is a pic where you can almost make out the three shielded runs.  i retired in place the problem wire and thats the way its gotta be.  ive used another wire to replace it unshielded.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-02-2018

i moved on to increase the wattage on the 40ohm power resistor.

i had a few choices and went with a 50ohm 10W resistor that seemed to take it really well with no heat sync.
i fabricated up a friction type metal bracket to pinch this new resistor up against the chassis then connected all my normal wires.

works fine so far.

you can see this new resistor and its placement in the upper left of the set up under that angle flange.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-02-2018

here is a shot of the final look under the set.

only one problem,, now that its all back together and on the shelf,,  i am picking up no short wave.
im thinking everytime i put it up next to the other sets,, its gets pissy. i dont think it likes the shelf.
perhaps i bumped something on the band switch,,,, dono.... will look later.

it rained today and there are some clouds but it seems to do a whole lot more of that cracks and pops like you hear on AM when there is a storm coming.  I plan to work the set really hard over the next few weeks and compare the cracks and pops to other sets... from there i will troubleshoot if need be.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - 35Z5 - 07-02-2018

A piece of copper braid RG-59 coax makes dandy shielded cable, but note corrosion resistant type is usually difficult to tin and solder. 

Many older sets had the wire run inside a closed coil spring type shielding..

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-03-2018

thanks tom,,,, i may do that.

update....
i do have shortwave,,

also,,
no poping or crackle.

Problem- I notice now with the volume all the way down, the radio powers up but the volume is up slightly like if you have the radio turned with the knob slightly up.
in other words i can power up the set and just after the "on/off" click, let it warm up and the volume is sufficient to hear throughout the garage.......
so....
i will attempt to insert a series resistor of some value on the wiper of the volume control so that when i power up and vol is down, there is no sound.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - 35Z5 - 07-03-2018

Check from wiper to ground side of control, if there is more than a couple hundred ohms the pot is issue. If there is resistance in ground circuit of control, volume cannot be extinguished.

I have a radio here that had intermittent issue with increasing volume at minimum. Problem was control(resistance 20K at minimum), lightly recrimping the control lugs fixed it. Been OK for over two years.


BTW  Here ya go, grid cap lead to tube inside shield uses spring, soldered to chassis.

BTW #2 The transformer's only duty is to power dial lamp in background, orig this was a battery/AC radio without dial lamps. Oversize speaker, matching output transformer(under chassis) and 50L6 courtesy of junk Zenith radio/phono.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-03-2018

I wish i had check this post earlier,,
i will check that ground leg.

when i checked the vol ctl resistance i think it went down to about 20ohms,, as i rotated the knob, it increased but somewhere around 100ohms which is barely a movement at all mind you, after 100, it jumps up to 450 ohms then down to 120 (ish).

the max resistance from wiper to ground is 780kohms,, specs call for 500 but i guess 780 isnt all that awful.
what i know is down in the lower area of rotation, the resitance is not stable.

btw- what i said earlier was dumb....

there is a 47k R in series with the vol ctl pot ,, after i thought about it ,, what i need to do is decrease the 47k resistor size.

well after trying everything right down to a jumper wire to bypass this 47k R, nothing changed.

i will do your check though, and update tomorrow.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - EdHolland - 07-03-2018

Great detective work on the defective shielded wire - nice to see that problem tracked down. The power resistor looks neat too Icon_smile

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-03-2018

thank you,, they are fairly low profile and ive found them useful in a lot of different things.

RE: *Solved Minerva Tropic Master model w117 "early"-crackle pop & no vol ****SOLVED - jcassity - 07-03-2018

hey tom,,,
i have some of that spring...
its wrapped around a master cylinder brake line on my ford bronco.
not sure why they did that around a brake line but its perfect fror an application like this.