Hummm...seems like it was some time back that you got rid of your humm chumm on that set and does this query on its dial cord mean that you either had NO dial cord on the set to make any reference to. Otherwise, being able to copy off its layout aside, or jumping right in and re- stringing it as you take off the old one.
Or maybe, you have been just hand cranking in the stations with the dial drum as is required .hi hi.
I might initially submit the top chassis layout and have you confirm if the units tuning condenser is
mounted on the end at a right angle to the dial scale as shown. Also if the tuning condensers is run to its fully meshed position, using its drum, was it turned cw or ccw (as viewed from the drums front)
in order to accomplish that. Also how many idler pulleys are mounted on the long slide rule, as the
graphics positioning on that photo only shows two. Also is there any chance that the travelling dial
pointer has provisions to be connected to the dial cord at more than the usual one connection point.
On a select few sets the pointer is connected to the dial cord at one of its edges and then across
to the other end of the pointer it may take a half turn wrap to the dial cord after it gets rerouted and
is moving in the opposite direction. How is the front dial scale logged out from its left side to right side?
Is its logging laid out in the all common 550------> 1600......or the rare, " sdrawkcab" 1600------> 550.
Also the positioning of any other idler wheels , since the two at the top of the slide rule dial are shown and are givens. Also, the third over, 1/4 in shaft is correct in being the tuning shaft ? and are there any other dial cord pulleys located just above it on the dial superstructures rear ?
Techie Referencing Photo:
http://img239.imageshack.us/img239/573/626spartontopchassisviefn9.jpg
ZUJ'ing for feedback
73's de edd
Hi Edd,
Thanks for the ideas,information and help in general. Must have been somebody else with the hummchumm, not me although I've had many sets with that problem. The good news is that it turns out my Power Transformer is not the culprit afterall, although it did get very hot and sizzled, but the smoke appeared to come from the rectifier tube, so possibly I've got a short from B+ to ground from there or a bypass condenser problem. Right now I've got Pwr transformer out of it since I wanted to check it out throughly which I did and it's perfect (Whew!!) .. Electrolytic cap circuitry is a mess (somebody got to this one before me) and so it's not ambulatory yet. Need to study. Never had a dial string on this, just turned the pulley wheel on the tuning condenser when it worked. Slide rule type dial with short-wave 6 to 18 MC on bottom increasing from left to right...BC band on top 600 to 1600 kc also increasing from left to right. 3 small wheels for string: 1 on the top left of slide rule dial glass (back side) and the other 2 are on the top and bottom of the right side of the slide rule dial glass. No other structures, guides for the string except where it fits inside the groved tuning condenser wheel and attached to spring eventually. Oh, and the dial pointer is the type which appears like it will fit on the string anywhere..the piece of string left to me with the pointer "mashed onto it" seems to be of that type, back and forth without any slight of hand tricks to make things more difficlt for those of us who are masochists & try to repair these old sets. It'll have to be put on hold till I see why I was getting a smoking rectifier socket (underside) , hot sizzling transformer (all of a sudden problems) and then finally to figure out this really screwed up riders schematic (or is me that screwed up? me i think) which has a center tap of primary leads from transformer going directly to the 15 mfd electrolytic capacitor yet it is tied into the EC cans's twist mount ground underside of chassis..? all that has been removed by me now (note to self: shuldda left it alone since that wasn't the problem but momma always taught me to replace the ECs first) if i ever sound like i even remotely know what i'm doing, I truly don't..this probably is a given after reading what I write on here.. So that's where I am now but Edd..Thanks for taking the time to write and post that URL of the overhead view of my Sparton 6-26 .. 73s back at ya... Doug
Looking at the units schematic, all seems in order. You do have the 2 section electrolytic electrolytic at the front of the chassis and either with separate wire leads coming out OR most likely using square and half circle referenced lugs recessed within its bottom end, and if the latter, using an INSULATED wafer mount, as that filters common neg needs to float from ground. In this design the R8-R12-R14 resistor trio sitting above chassis ground referencing establshes a negative voltage source for 1st grid biasing of the output pair of tubes. If the former tenant has / had
used a metal plate mount for putting in a new replacement cap and grounded that capacitors 4 ground lugs to chassis ground,
expect a radiantly resplendent glowing of the output tubes innards and a somewhat fierce power supply current drain.
(As in ...'moke, 'moke, I smell 'moke !!)
You said:::::---which has a center tap of primary leads from transformer going directly to the 15 mfd electrolytic capacitor----:::
Wherein I think you mean "has the center tap of the transformer secondarys high voltage winding.yada..yada.."
You said:::::---It'll have to be put on hold till I see why I was getting a smoking rectifier socket (underside) ,----:::
If you are blaming the 5Y3 tube, very remote chance...confirm if it possibly has lost its shell glazing and had an interelemental arc-over and a resultant arc trail burning in an ever deeper path.
Or look at the tube socket and see if its a wafer style design where dirt / moisture / cleaning agents can wick inwards and cause the MUCH easier effect of
an insulative breakdown.
Cheaper plastic sockets that have a strap across the bottom for mounting can also break down at a pin and develop an arcover and progressively increased carbonized trail across it also.
Somewhere In the operations put yourself an inline 1/4 A fast blow fuse at the HV secondary windings centertap.
The provided technical drawing of the sets dial string up is not scaled properly, but with what info you just gave me and the confirmation of the corner dial idler pulley(s) closest to the tuning condenser, coming flush with them, has given me the potential dial string routing.
Even though you didn't give me the info as per the direction to rotate the caps tuning drum to get its plates fully meshed....CCW..right ?
73's for now
Edd
Hi Edd,
CW actually to get the plates fully meshed. actually it looks upside down to me compared to most tuning condensers but just the way it's designed. fully CCW opens the plates up pointing down towards the top of the chassis. hard to explain.
Amazed at all this information I'm receiving from you here which is priceless. Thanks!!! Yep, the old original Electrolytic Can capacitor is , or was with with the wafer insulated mount. It's broken. The square was 15 mfd and unrecognizable, but the other was the 10 mfd ..Then something I've never seen before in my 5 years of trying to teach myself this stuff from books is an electrolytic capacitor can that reads on the side after giving the 2 or 3 main values.."Plain 25 mfd at 25 volts" what?? That's not in the schematic anywhere? Then after that, you see engraved in the can-"Can -common neg" which you expect to see, but that 25mfd@25volts is a new one to me. that secondary high voltage lead center tap (yellow red wire) which goes to one of the twist mount lugs that secures the 'wafer insulation' from chassis/can, now broken up. I'll have to figure out a new way to wire up this electrolytic capacitor configuration without the benefit of the factory can capacitor,wafer mount, etc since nothing good is going to happen until I get these back in the circuit. I bet they don't have these available anymore do they? I'll check the standard places at Tempe and radiodaze along with a few more..Don't know how to duplicate that floating insulated ground at the moment; maybe tomorrow I will.
73's Edd and Thanks again for helping me out here..
Doug,
If you desire, send me an email stating whether the insulated washer is 3 or 4 lug and I will drop one in an envelope to you. I got a fist full of the 3 and 4 lug types. The 4-lug has 1-13/16 inch screw mtg centers and the 3-lug has 1-1/2 inch screw mtg centers.
Radiodoc
HI and Thanks!
I'll try to snag your email address somewhere here in the forum so I can write RD .. This is the 3 lug type with the 1-1/2 inch screw mtg. centers I'm working with. Thanks again! Doug
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Well, thank goodness that The Good Samaritan...aka le Radio Docteur... came to your aid on the
insulated wafer mount for the canned electrolytic. I still have a few of the metal ones, but if
that was my situation, surely I would have had to revert to the tracing off onto a sheet of 1/16 in phenolic. Which I do have, and then the making of the outer profile with a saber saw and belt sander and the inner hole with larger Dremel tool burrs and the fine 4 ground lug slots with a dental burr and micro Swiss pattern files.
With your further info on that cap, I now see that it is the largest profile of alum cylinder case, with its 4 equi spaced ground lugs. There is another smaller case design that only has 3 equi-tri spaced ground lugs.
In reference to those markings on the side of your electrolytic, looking at the bottom phenolic sheet disc / seal on the unit, there is room for up to 4 lugs to be placed there for up to 4 separate internal cap sections. In order to identify those identical appearing terminals, they will go up next to a terminal and notch in, in clockwise order, either a square, half circle, or triangle symbol or nothing at all ...the latter of which you have now discoveed as being "labeled plain". Now take a close look at that cap and I fully expect that plain terminal to have been snipped off flush. That value that you read off would typically have been used for the cathode bypassing function for those output tubes had they used a cathode resistor for bias acquisition, however,
in your case they opted for the aforementioned floating ground technique to acquire your AF output tubes 1st grid biasing, precluiding the neccessity of that cap section. Some prior radios design typically used that section, but the carry over of stock parts to this newer units design change permitted them to deplete their still on hand old stock.
Found your B+ problem yet, If mine, I would already have a new premium porc or ceramic octal socket in that hole, a new 5Y3 in it, along with the added placement of a safety fuse in the center tap line .
73's de Edd
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Hi Edd,
I've tried to post back to you twice here but each time it 'eats it' .. Got to be user error I think.
ep, you and RadioDoc have been lifesavers in this project and will keep you posted aat each development.
Haven't gotten the new 5Y3GT tube nor the loctal soceket replacement yet but soon.... Doug
HI Edd,
Just an April Update here on my continuing battle with the Sparton 6-26 (circa 1947-48) .. With your help and that of RadioDoc, I've got here working again and she sounds excellent! Thanks again for all your help .......73's to ya & more later Qrx Nxt ...- .- Doug