I think it is 19LZX.
I bought it from Terry about a year or so ago.
I remember Terry having bought it in Kutztown abouit 5 years prior to that. It actually was working. I helped him to stuff it in his Ford Falcon (I think it was that).
It has been sitting in my workshop for a couple of years, and with me making no progress on my Thorens turntable, I decided its number has come up.
So.
Today I took the chassis out.
Here it is.
[
attachment=22846]
The look inside.
[
attachment=22847]
[
attachment=22848]
Asbestos. Never thought it would be in a 1933 Philco.
[
attachment=22849]
[
attachment=22850]
As you can see there was an attempt to fix something.
So, judging by the picture of the underchassis, methinks it is V121 V3 as there is that capacitor 0.05uF added.
Well, the work begins.
Restuffed 5 backelite blocks.
Another 4 are left.
Then there is the filter block. Should not be hard, it is the tin can 70 style, the block should be simple pullout wrapped in fishpaper.
Electrolytics are another problem.
So...finished the backelites, extracted the tone control and the electrolytics. They might've been the replacements but are original Philcos.
Extracting of the tone control proved to be somewhat onerous: the tone control is squeezed between the front panel and the closest electrolytic cap and its holder clamp. Without full removal of that holder clamp the tone control could not be tilted out of the hole for the shaft. The holder clamp is held in the middle by a thick steel wire.
This one.
[
attachment=22869]
Unbending it without any fulcum and wires around was not simple. But I prevailed.
[
attachment=22872]
Now, about that tone control.
[
attachment=22870]
The stamped number could not be located in Ray Bintliff's book. Seems to end with 940.
Also it is 3-cap thing. From the "Evolution of 89" I did not see any 3-cap ones used, only 2-cap.
Any help with the info is appreciated.
Nice to see this coming along. Looks great!
The model 19 sure is a cramped little set. The tone control and electrolytics have been a struggle on the two I serviced as well. Good sets once restored though.
Nathan
Do the cathedrals also have the asbestos-coated shield or is it an LZ feature?
No - I don't recall any asbestos shield in the 19 cathedrals. Never saw anything like what your photo shows.
Here's the photo album for one of them if you're curious -
https://flic.kr/s/aHsmKEp53D
So, guys, before I resort to going outside this Phorum asking Philco questions:
Does anyone know what 06940 tone control hides inside?
Don't go to Ray's book: it does not have it.
Riders (I went through all 4 volumes containing 19/89 info) also has none.
Measuring with meter yields 29nF/27nF/17nF.
Considering ageing and nearly doubling the value, my guess is 15nF/15nF/10nF.
Nathan,
I wrote earlier. I haven't found any 3-cap ones in there. Have you?
In a doc in Riders it shows a regular PN. It is a 2-cap one.
Ah I see now. Yes that is different from the tone controls I’ve seen on the 19B:
https://flic.kr/p/WMvrpx
I guess the chair side used a different part?
Might be.
I also checked 14LZX docs, that are common to 19LZX, no mentioning.
I should probably just check 14LZX sch, see if they are shown there.
OK, I think I figured what is inside.
The values are cut in half as per rule of thumb, that the caps roughly double in capacitance over time from the 1930-s by now.
[
attachment=22888]
This is an equivalent of simply putting 13nF i/o 10nF and 10nF i/o 4nF with no 20nF in between them.
Which is what I was about to do, but I measured between the two caps and realized the capacitance is more than the serialized value, so I concocted this.
Not sure....probably would be easier to use 3 caps i/o 4.
Translation for we Americans who do not use the nF standard:
15 nF = 0.015 uF
10 nF = 0.01 uF
20 nF = 0.02 uF
8 nF = 0.008 uF
Thanks for posting the graphic, Mike. I was not familiar with any different standard in 19LZX tone controls.
Ron,
I could not find any mentioning of it anywhere whatsoever.
I even resorted asking in the ARF. So far no answer.
I mean.....it is not even that important, any similar control used between a 42 plate and the GND/Rect negative will work.
Just....unusual.
Obviously my question has everyone scratching their heads as no one on both forums has been able to tell me anything.
I think the cap between the two contacts, at least in theory, could be useful in the following manner: it lets the sliding contact engage patially charged caps. That is, if the cap is just hanging by itself, its voltage is equal 0, and when connected, it will charge from 0 to full value, whereas when partly charged (you can see how those are lesser values than the bridging cap, thereby charging to the larger portion of the voltage) they will maybe pull less current, create less spark and make less scratchy noise.
I dont have the answer why.
But I will have to stuff it with something, I guess.