The PHILCO Phorum

How do I know from a schematic which pins are which on the tube socket sitting in the chassis? The heater pins are easy to identify because of continuity testing and they seem to be larger diameter but what about the others? I can't always trust tracing the circuit because the radio came to me non functioning and the circuitry doesn't appear to be correct in some instances when looking at the schematic. Is there a clock position that's always constant or something? -thanks

You can look up the pin layout and tube data at the following database (there are others):
http://www.nj7p.info/

Click on the "Tube SQL Database", enter your tube number and click "Lookup".
It will give you a diagram of the tube with the pin numbers.

Here's an explanation of how to count pin numbers when looking at the bottom of the tube: http://www.dogstar.dantimax.dk/tubestuf/pinout.htm

When working on a set I try to have tube data handy. one of the best places is Franks electron tube data. download the PDF and print.   http://frank.pocnet.net/

Well there are two ways. One is to whip out your handy dandy 1940 tube manual and look it up. Nowdays I look  it it up online. Some schematics have the pin numbers indicated on them some not.

I think you maybe be asking how do I count pins on the bottom of a tube?

Older standard base tubes: 4, 6, and 7 pin tube are simple. Find the two fat pins looking  from the bottom. Face them towards you. The pin on the left is pin#1 count clockwise to determine the others. For instants a 4 pin tube pin 1 is the fat pin to the left. Pin 2 is the thin one above it. Pin 3 is the thin pin to the right of pin 2. And pin 4 is the other fat one.
On the 5 pin tube two of the pins are closer together. Pin 1 is the one on the left of two that are closer together, pin 5 is the one to the right of pin1.
Schematics that don't pin numbers doesn't mean that the connections are layed out in the order in which they appear on the schematic.

I see I'm late to the party! Slow typer.

Working on a 610 chassis are you??

(08-13-2016, 11:55 AM)Radioroslyn Wrote: [ -> ]Working on a 610 chassis are you??

Yup, I've got a 1936 610 "bullet" - the one with the oval dial glass. It's been a fun restore so far. I can tell by the materials used and the methods of repair that it's had multiple people working on it over the last 80 years. Some of the repairs are sloppy by my standard so I'm trying to clean up things.

(08-13-2016, 11:49 AM)Radioroslyn Wrote: [ -> ]Well there are two ways. One is to whip out your handy dandy 1940 tube manual and look it up. Nowdays I look  it it up online. Some schematics have the pin numbers indicated on them some not.

I think you maybe be asking how do I count pins on the bottom of a tube?

Older standard base tubes: 4, 6, and 7 pin tube are simple. Find the two fat pins looking  from the bottom. Face them towards you. The pin on the left is pin#1 count clockwise to determine the others. For instants a 4 pin tube pin 1 is the fat pin to the left. Pin 2 is the thin one above it. Pin 3 is the thin pin to the right of pin 2. And pin 4 is the other fat one.
On the 5 pin tube two of the pins are closer together. Pin 1 is the one on the left of two that are closer together, pin 5 is the one to the right of pin1.
Schematics that don't pin numbers doesn't mean that the connections are layed out in the order in which they appear on the schematic.

I see I'm late to the party! Slow typer.

Thank you for the education on this. Are you saying with your last sentence that if the schematic, like the one I posted, doesn't have the pins numbered that I can't necessary refer to that layout? Stated another way. If the two fat pins is for the heater and the one thin one to the left of the heater on the schematic shows it connecting to a grid that the socket sitting in my chassis might actually be something like the plate? I suppose I should refer to the materials shared above as the "gospel" truth for that tube pin layout. - This could be why I am second guessing the circuit.

Hi....

The RCA Triple Pindex is, by far, the most easiest and concise index to use for tracking down pin numbers. Take a look at it.....

https://www.amazon.com/Triple-Pindex-Rec...B002DS74PG

And here.....

https://www.google.com/search?q=RCA+Trip...BygC&dpr=1

These are some great resources, thank you for the quick responses everyone. I'll get back to the bench with these materials. - Thank you!

Here's the difference between the Philco schematic you have posted and the pin-out diagrams in the databases:



The Philco schematic is on the left and the pin connections as seen from the bottom of the tube are listed in RED numbers.  You need to look at the actual elements in the tube, i.e. the plate (pin 2), the cathode (pin 5), the grid closest to the plate (pin 4) etc.  The grid cap on the top of the tube is unnumbered.

Hope that helps.

(08-13-2016, 01:15 PM)klondike98 Wrote: [ -> ]Here's the difference between the Philco schematic you have posted and the pin-out diagrams in the databases:



The Philco schematic is on the left and the pin connections as seen from the bottom of the tube are listed in RED numbers.  You need to look at the actual elements in the tube, i.e. the plate (pin 2), the cathode (pin 5), the grid closest to the plate (pin 4) etc.  The grid cap on the top of the tube is unnumbered.

Hope that helps.

Yes that helps tremendously. I see why I was getting so confused. In this example I was looking at the pin to the left of the cathode ground (pin 1) thinking that it was either pin 2 or 6 and it wasn't lining up when I traced the circuit. I guess they laid out those schematics in the easiest way possible and not actually by order of pins. Thanks for the image. That helped clarify things for me.

(08-13-2016, 12:57 PM)IowaPhilco Wrote: [ -> ]

(08-13-2016, 11:49 AM)Radioroslyn Wrote: [ -> ]Well there are two ways. One is to whip out your handy dandy 1940 tube manual and look it up. Nowdays I look  it it up online. Some schematics have the pin numbers indicated on them some not.

I think you maybe be asking how do I count pins on the bottom of a tube?

Older standard base tubes: 4, 6, and 7 pin tube are simple. Find the two fat pins looking  from the bottom. Face them towards you. The pin on the left is pin#1 count clockwise to determine the others. For instants a 4 pin tube pin 1 is the fat pin to the left. Pin 2 is the thin one above it. Pin 3 is the thin pin to the right of pin 2. And pin 4 is the other fat one.
On the 5 pin tube two of the pins are closer together. Pin 1 is the one on the left of two that are closer together, pin 5 is the one to the right of pin1.
Schematics that don't pin numbers doesn't mean that the connections are layed out in the order in which they appear on the schematic.

I see I'm late to the party! Slow typer.

Thank you for the education on this. Are you saying with your last sentence that if the schematic, like the one I posted, doesn't have the pins numbered that I can't necessary refer to that layout? Stated another way. If the two fat pins is for the heater and the one thin one to the left of the heater on the schematic shows it connecting to a grid that the socket sitting in my chassis might actually be something like the plate? I suppose I should refer to the materials shared above as the "gospel" truth for that tube pin layout. - This could be why I am second guessing the circuit.

You got me there. General on a schematic the heater pin are in the proper place. Most of the it doesn't matter cause one side is at 6.3vac and the other is a chassis ground. But when you have a transformerless set (ac/dc) the heaters are in series then it can be important to know which pin is which.

This  was a problem child I was working on a few months ago. The tubes at each end the the volt was too high and in the middle it was too low. The 1LN5 had only .5v and was inoperative, the 1LE3 and !LB4 had too much @ 1.75v. As you'll notice 1 pin is on the left and 8 is on the right as it should be. This makes it easier to troubleshoot.

Schematic are drawn to have the least of wires crossing to avoid confusion ( unless it's a Crosley). This doesn't necessarily correspond actual arrangement of the pin placement on the tube base. Notice that your 610 doesn't show any caps on the tube that have them.

I think I answered your question.

Well, I spent this evening with tube print outs and the information you guys gave me and all the circuity is lining up now. Bakelite blocks were removed from my chassis and some resistors and capacitors were soldered directly to the tube socket making things difficult for me to follow. With everyone's help I'm able to figure out what's been changed now. Good stuff. Thank you again!

(08-13-2016, 01:50 PM)IowaPhilco Wrote: [ -> ]

(08-13-2016, 01:15 PM)klondike98 Wrote: [ -> ]Here's the difference between the Philco schematic you have posted and the pin-out diagrams in the databases:



The Philco schematic is on the left and the pin connections as seen from the bottom of the tube are listed in RED numbers.  You need to look at the actual elements in the tube, i.e. the plate (pin 2), the cathode (pin 5), the grid closest to the plate (pin 4) etc.  The grid cap on the top of the tube is unnumbered.

Hope that helps.

Yes that helps tremendously. I see why I was getting so confused. In this example I was looking at the pin to the left of the cathode ground (pin 1) thinking that it was either pin 2 or 6 and it wasn't lining up when I traced the circuit. I guess they laid out those schematics in the easiest way possible and not actually by order of pins. Thanks for the image. That helped clarify things for me.

Whopppsss it does show the caps ! Got to look before I type.
+1 Bob Unlike me very succinct. 1 pic is worth a 1000 words!