[Jbaker]

Hello.  I am working on a model 90 SN A40030. It has a single 47 output tube.  The schematic and partslist shows the tone control as part number 4037-A. However, the part that is installed is 03137.  I looked at the schematic for the dual 47 output tube model and figured out the wiring.  Can anyone tell me the value of the 3 internal caps? I couldn't find any documentation on the 03137.

Thanks -Jim

[morzh]

http://philcoradio.com/tech/images/90b.jpg

They are shown next to the caps in the sch.

[Jbaker]

Thanks for the response.  Unfortunately, that schematic is not correct for the tone control in my set.  If you look at the schematic for the model 90 with dual 47 tubes, the tone control is slightly different (p/n 03137).  I have the single 47 output tube with the tone control shown on the dual 47 schematic.  There are 5 wires coming out of the tone potting instead of 4.   The 3 caps may be the same, I just want to make sure. 

Thanks again for any help.  Jim

[Jbaker]

I just took a look at the other schematic and found my answer.  Thanks for pointing me in the right direction.

[morzh]

Single 47 registered in my mind.....but all versions are there.

Note: The first cap I use of a lower value. Otherwise from the very first turn of the knob the highs almost disappear.

[Jbaker]

Single 47 registered in my mind.....but all versions are there.

Note: The first cap I use of a lower value. Otherwise from the very first turn of the knob the highs almost disappear.

It looks like the 03137 control incorporates the change you suggested. Do you recommend an even smaller value?   I hope my math is right.

03137 tone control
Pos 1.  .006uf. (.01uf in series with .015uf)
Pos 2.  .015uf. (.01uf shorted out in series with .015uf)
Pos 3.  .025uf (.01uf in parallel with .015uf)

4037-A tone control
Pos 1.  .015uf
Pos 2.  .025uf 
Pos 3.  .035uf


There have been several errors in the schematic and parts list.

1.  Wrong tone control listed. Parts list says 4037-A but it is 03107
2.  There is an extra bakelite cap accross the choke (item 55). It is not on the chassis diagram or schematic.  I found a mention of this by another member in an earlier post.
3.  Item 38 is listed as a 3903-P cap.  The part that was installed was originally stamped 3903-R but there is another stamping on top of it making it difficult to read.  That actual configuration doesn't match any of those listed for 3903s. 
4.  The metal can caps were not correct which is mentioned in the tech notes.  


It would be pretty difficult to figure this stuff out without this forum.  THANKS!

Jim

[morzh]

The way it is in 2x47 tubes the tone control should be fine the way it is; in other versions the first cap would be 0.015uF and this to me is a bit too much.

[jjfritz5528]

I know this thread goes back a bunch of years, but I am currently restoring a Model 90 with the one 47 tube also. I wanted to confirm what was originally posted and provide some additional information, including the other differences noted.
I also have a 03137 for the Tone Control. I was planning to replace the existing caps as noted in the "Philco Condensers and More" booklet by Ray Bintliff. They are 0.015, 0.01 and 0.01. It also lists the 4037-A, shown on the schematic, as having the same values.
Should the 0.015 be smaller, as mentioned, 0.006? Then what about the other two?
All the mention of Shorted, Series, Parallel has me confused. The switch just puts each subsequent cap in Parallel, which increases the Capacitance as the switch increments. Right?
My 03137 also had 4 wires coming out of the tar to the 3 contacts. 2 were on the second contact. I tried to measure the existing ones, but I think they were too far gone to make sense. I got 0.008, 0.023 and 50pf!
I was hoping to clarify this, prior to re-assembling, but will probably experiment with the values that I feel give the best response.
I also had the extra capacitor block across the Choke. It was a #4989-J, 0.01mf.
I also had a #3903-P for Item #28, Coupling cap between 1st and 2nd Audio. I think 0.01mf is the correct value, buy Ray's booklet shows it as a 0.1mf.
I also added the resistance value to Ray's Table for the Choke #4951, 460 ohms in my set.

[Radioroslyn]

>The switch just puts each subsequent cap in Parallel, which increases the Capacitance as the switch increments. Right?

Yup sure does! 
The values of these caps are not all that critical they just determine how muffled the audio sounds. With the control all the way to the left there is no cap in the circuit. To me that position sound pretty good. I looked at the diagram and saw that the caps listed seemed large when you add them all up w/the switch to the far right. I opted to shrink them down to .005 ea (ymmv).

A lot of modern set will have a .01 mfd cap across the opt and sometimes I would augment that w/a series resistor to brighten the sound a bit. Usually a couple of hundred k will do it.

> I also had the extra capacitor block across the Choke. It was a #4989-J, 0.01mf. 

Funny you should mention it mine had it too. But I couldn't find it in any of the diagrams. It was badly over heated tar had melted all around it. It isn't a necessary part as it's used the make a tuned circuit w/the filter choke to buck the 60cy hum. If you up the value the filter caps by just a few mfds like from 6 up to 10 your good. The previous owner just thew in some filter caps and a fuse kept playing the thing till it dyed. It burn out filter choke. Fortunately I  had the model 70 pasts set and the according the lists it was the proper the for the 90 and the one in the 90 was for the 70. The bad one in the 90 looked bigger and had more inductance. Swapped the choke the p/s was back in business.

de N3GTE

[jjfritz5528]

Terry-
Thanks! Another wealth of knowledge!!!
Once I get ready to power up, I might try a couple different, lower values and see how it sounds. The Tone Control was the last thin to do. So it's easy to accomplish before I bury them inside the metal cup. This Model 90 Chassis is in a Lowboy Floor Cabinet. I also have a Cathedral waiting in the wings, same model. So I will see if these variations are the same in that one.

You wouldn't happen to have a junker Philco 60/60B chassis that has a 2nd IF transformer you would be willing to part with? The one coil is open and it's not near the outside, it's buried near the core. This isn't something I want to tackle rewinding. Or a source for one?

Thanks for the good information!

[jjfritz5528]

Terry and all -
I tried several different combinations of caps and IMHO and for this particular set, all three caps at 0.01mf seem to sound the best. My high frequency range may not be the best and others may find different values work better for them.

[radiorich]

Hello john,
Well that is what counts what sounds good to you right !

Sincerely Richard

[RodB]

Sounds good to me! Us old farts don't have the range anymore. I remember when I was a senior in high school hearing the 15,750 Hz horizontal sweep on a TV squeal. Nowadays I'm lucky to hear 6000. (Spell check changed it to facts!)

[462ron]

Rod I don’t know about that. I’m an old fart I can still hear the 15,750 cycle singing constantly, even in my sleep! I guess that’s a different problem!

Ron

[morzh]

Ron


Same exact. I've been hearing that for 2.5 years now, ever since I'd heard that sound that my work laptop started making, and it never left me since, even after the laptop had been replaced

I think they call it "tinnitus". (Nothing that has the "tinite-" as a part of pronunciation could be good, just look at Tennite grills )
This said, I hear my classical music just fine. Either the classical trange is overexhaggerated, or my hearing is still there....