This 116B was a Craigslist find that Matt (wardmc1) saw and alerted the phorum to the post. It was only about 20 minutes from me. The cabinet is painted white and will get stripped this winter if I can do it with citristrip. If I need to use something stronger it will have to wait for outdoor weather.
The chassis is dirty but not too rusty. Here is the LINK TO THE SCHEMATIC My main concern was the extra rotary switch on the back. Lord knows what someone has done…
The chassis came out of the cabinet without issue. Surprisingly the two front rubber cushions are very soft and pliable. I did buy new ones assuming they would be bad but these still seem good. The rubber on the back chassis bolts are another story, definitely needs replacement.
Once I got the chassis out and could see what the switch was connected to it became obvious that its simply an aux input switch unless I’m not understanding things. It switches the grid cap for the 1st audio 77 tube between the screw connector on the switch face in one position and the normal connection to the front end of the radio at cap#65 in the other position. It was a little difficult to figure out since its actually a 3 position switch (probably something the person had in the junk drawer) but is only used in two of the 3 positions. Most of the connections and wires are actually grounded wire shielding. The switch location in the circuit is the red box.
It looks like this may be the means to add a phono jack to the radio. It treats the radio as a tuner and offers another input. At the time, a phono input would be the most probable choice. It appears to be made with period-correct parts, so it may have been a popular modification to be made by the owner or a dealer.
+1 Go ahead and remove it as it's not a very good way to connect it. When it's in the aux position it removes the grid bias from the 77 tube and it disables the volume control.
Just as an aside I've been fooling w/my late model 116B. I got it working and aligned back last winter. Haven't done much w/since so the other day I took it for a spin and was doley impressed. What a great sounding set! Plenty of rockem- sockem audio ever w/the smaller 8"spkr! Dial calibration is on the nose. Power transformer run cool unlike the 116X.
Right now I've got it apart replacing the rubber bushings on the tuning cap. Little tip if you need to replace them do it when you are recapping up by the volume and the tone control. It gives you much better access w/ the controls partially disconnected. it's kinda tight between the the controls and the bandswitch to get the ground braid unsoldered. You don't necessarily have to remove the controls unless you want to.
I think you'll really like it when you get it done.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Ad ons like that switch are usually one of the first things that gets fixed if I acquire a new old radio, nine times out of ten they are not wired in correctly, and even if they were I really have no need for them as I have plenty of sets that already have factory phonograph connection points in the back. If you want to see a really sloppy job of one of those, you should see the ones where they hack into the grid cap lead of the first audio tube, like the Stromberg Carlson model 228-H I have, I can imagine nothing but a non stop hum whist the set was on.
Regards
Arran
Started to work my way through the chassis coils. Here is the LINK TO THE SCHEMATIC.
My very first measurement was ANT to GND and I was expecting about 6 ohms...but got an erratic 1.6 Meg. I think the Transmission Line Transformer #4 has an open in it. What is a Transmission Line Transformer??
Next I was checking the output transformer, field coil and voice coils. The speaker looked to be in good shape, no tears or holes in the cone.
A to B = 1.165kohms
A to C = 168 ohms
B to C = 1.333kohms
A to D = open
B to D = open
C to D = open
E to F = 0.2 ohms
So the field coil and voice coils seem good but half of the output transformer is open unless I'm misunderstanding something.
So far that's all the bad news. The power transformer looked good as do the Audio transformer #89, and the 1st, 2nd and 3rd IF transformers. My eyes started to cross as I looked at the gang of rotary switches for bands and the various RF, oscillator and antenna coils.
Here's a pinout/resistance of the coil in hopes this will aid you to troubleshooting and repair. Resistances are measured from ground to each terminal. Look at the good side if it #38 wire it's only abt 6' long.
The output transformer seems like one side is open. The good news here is that there are a number of Philcos that use the same transformer. What you want to look for is a set that uses the p/p 42's triode connected or a set that has three #42tubes.
Dare I ask how is your shadow graph coil? That one is abt 1100' of 38 wire.
Obtw There's a 116B cabinet you know where. Price is very high but maybe after it doesn't sell for a while it might be negotiable.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 11-14-2018, 08:20 PM by Radioroslyn.)
Thank you Terry!!!!!
Good info. I think I am going to be needing your help on this one. Seems like a lot more radio than I've worked on before. I have not checked the shadow graph coil yet....
I did see that 116B cabinet on ebay. I've started stripping the white elephant that is the 116B cabinet that I have. It is sitting overnight and I'll know more tomorrow about what is under the paint.
I think its just the 6.4 ohm section that is open although I did not write down the others they were low ohms, not open.
> I think I am going to be needing your help on this one. Seems like a lot more radio than I've worked on before.
No Worries! I'd much rather work on these that one of those confounded ZTO. It's a nice compromise between working on the later 37 and 38-116 or '690. From an electronic standpoint it's a pretty straight forward circuit w/o the frills of afc or variable IF bandwidth. After you get the paper caps done and check the resistor for tolerance then test the tubes. With the issues you've already found they don't stop you from giving the set try. The output transformer will work w/one side open and it won't damage output tubes. The ant coil will probably lower the reciever's sensitivity but it's got a lot of sensitivity so don't think it's a showstopper.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
(11-15-2018, 01:31 PM)Radioroslyn Wrote: I'd much rather work on these that one of those confounded ZTO.
LOL...you've got that right!
The shadow graph coil measured 430 ohms if I traced the wires correctly. All the tubes are good. Good to know that about the half open output transformer, so at least I can test before finding one.
So Terry, I think this is where my open is on what the schematic calls the #4 "Transmission Line Transformer" and that seems to make sense with the coil pin out you provided. The antenna transformers are #5 "Antenna Transformer (Long Wave) and #8 Antenna Tranformer (Standard, Police, Short Wave). What does #4 coil do? I've not seen a "transmission line transformer" before.
Hmmmm.
Well I'm not quite sure. Section 6 of the band switch mostly is switching between the two antenna connections. On the back of the set there are two screw terminals these are for the LW ant. The two fastenstock clips are for the BCB and above. #4 isn't part of the tuned circuit for the ant so I'm thinking that is not particularly critical (that's what #8 does). 4 is connected when the bandswitch is set to the BCB but the signal from the ant can go thur 6 and feed the ant coil.
Like I said don't think it's a show stopper. If I had an inductance meter I could measure the one I have and you could add a small value choke to emulate your open section. Another possibility would be the add a small cap across the open section. This would apply the rf signal form the top of the coil to the second second section.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
What is a Transmission Line Transformer??
