Checking a 302

[poplar1]

There should not be a loud pop when hanging up on a 302, even when you manually push down the plunger slowly with the receiver close to your ear.

If there is a pop, then it's likely to be caused by one of these:
(1) hookswitch contacts out of sequence, or
(2) open red handset wire, or
(3) improper wiring.

(1) Hookswitch: The brown-blue and green contacts need to open first; this opens the receiver so you don't hear a pop from the voltage spike when the yellow and brown-yellow open up to disconnect the phone from the line. (This sequence is something that you can always check on a WE phone--but not necessarily with other manufacturers.) So you may have to adjust the contacts so that the receiver contacts open first. But before making any adjustments, read on:

(2) Handset cord: If there is a pop, it may also be an open red handset wire, so before adjusting the hookswitch contacts, remove the green hookswitch wire from GN on the ind. coil (or white handset wire from W on the dial), and make sure that there is no pop when you remove the green (or white) wire and put it back a few times. The dial tone should go away each time, but without a pop. If there is a pop, then adjusting the hookswitch contacts won't help.

(3) Improper wiring: Make sure none of the spade tips is touching another terminal. If you are using a handset cord with colors other than White (receiver), Black (transmitter) and Red (common), be sure you substitute the same color on each end.

It's possible that the induction coil or talking capacitor is defective, but this rarely happens. One way to check the capacitor is to unscrew the transmitter cap and remove the transmitter unit. After removing the transmitter, if the capacitor is good, you should hear dial tone for another second or two, then it should go away.  If on a POTS line, you can then hear a slight hum in the background (monitor). If not, the capacitor may be defective (open).

With the transmitter out, if the line is in use, you can hear dial tone, dialing, conversation and incoming ringing, but won't be able to transmit. However, the line will not be busied out even if you leave the handset off the hook, so long as the transmitter isn't reinstalled.

If you still have a dial tone after removing the transmitter in a WE or NE 302, AE 40, SC 1243, or North -H6, then probably something is not wired right.

[Scotophor]

What would the symptoms be if the talking capacitor has excessive leakage or is completely shorted?

[poplar1]

What would the symptoms be if the talking capacitor has excessive leakage or is completely shorted?

A. J., the following symptoms appear with a shorted talking capacitor (red and black wires connected to C on induction coil and BK of the dial):

Loud pop when you hang up, when you first turn the dial, and when the dial returns to home position.
Also, when you remove the transmitter, the dial tone is still there.

Thanks for pointing out another source of the receiver pops:

(4) Shorted talking capacitor

[NorthernElectric]

(1) Hookswitch: The brown-blue and green contacts need to open first; this opens the receiver so you don't hear a pop from the voltage spike when the yellow and brown-yellow open up to disconnect the phone from the line. (This sequence is something that you can always check on a WE phone--but not necessarily with other manufacturers.) So you may have to adjust the contacts so that the receiver contacts open first. But before making any adjustments, read on:

(2) Handset cord: If there is a pop, it may also be an open red handset wire, so before adjusting the hookswitch contacts, remove the green hookswitch wire from GN on the ind. coil (or white handset wire from W on the dial), and make sure that there is no pop when you remove the green (or white) wire and put it back a few times. The dial tone should go away each time, but without a pop. If there is a pop, then adjusting the hookswitch contacts won't help.

I'm having this trouble with my NE 352 project.  I bought the 352 from eBay and the description stated that 'internal parts were removed'.  This included the coil, capacitor, and ringer.  I was OK with that because I got it cheap (except for the shipping) and I knew that I could use parts from a 302 which would be more readily available.  I could see the dial and switchook in the seller's photos, and asked if the dial was intact and unaltered.  What I didn't think to ask about was that every wire in the phone was cut!  Who would do that to a phone in which every connection can be disconnected by unscrewing a spade terminal?

Anyway, I picked up a no-dial 302 as a parts donor and in addition to the coil, capacitor, and ringer, I also swapped over the hookswitch contact bundle due to the cut wires on the original.  I have it all wired up and except for the pops, it works fine.  After verifying all of my connections (several times) and trouble-shooting off and on the last couple of days, I'm pretty sure the source of the pops is the hookswitch.  I pulled the hookswitch back out and checked to make sure that I didn't lost the plastic insulating sleeves on the screws.  After finding this topic, I tried the green wire test and I can disconnect and reconnect it without the pops.  I have have also observed the operation of the switch contacts under magnification, and as far as I can tell they open and close pretty much simultaneously.

So, before I start bending stuff, what is the best method of adjustment to get the BB-GN contacts to open first/close last?   

[NorthernElectric]

(1) Hookswitch: The brown-blue and green contacts need to open first; this opens the receiver so you don't hear a pop from the voltage spike when the yellow and brown-yellow open up to disconnect the phone from the line. (This sequence is something that you can always check on a WE phone--but not necessarily with other manufacturers.) So you may have to adjust the contacts so that the receiver contacts open first. But before making any adjustments, read on:

(2) Handset cord: If there is a pop, it may also be an open red handset wire, so before adjusting the hookswitch contacts, remove the green hookswitch wire from GN on the ind. coil (or white handset wire from W on the dial), and make sure that there is no pop when you remove the green (or white) wire and put it back a few times. The dial tone should go away each time, but without a pop. If there is a pop, then adjusting the hookswitch contacts won't help.

I'm having this trouble with my NE 352 project.  I bought the 352 from eBay and the description stated that 'internal parts were removed'.  This included the coil, capacitor, and ringer.  I was OK with that because I got it cheap (except for the shipping) and I knew that I could use parts from a 302 which would be more readily available.  I could see the dial and switchook in the seller's photos, and asked if the dial was intact and unaltered.  What I didn't think to ask about was that every wire in the phone was cut!  Who would do that to a phone in which every connection can be disconnected by unscrewing a spade terminal?

Anyway, I picked up a no-dial 302 as a parts donor and in addition to the coil, capacitor, and ringer, I also swapped over the hookswitch contact bundle due to the cut wires on the original.  I have it all wired up and except for the pops, it works fine.  After verifying all of my connections (several times) and trouble-shooting off and on the last couple of days, I'm pretty sure the source of the pops is the hookswitch.  I pulled the hookswitch back out and checked to make sure that I didn't lost the plastic insulating sleeves on the screws.  After finding this topic, I tried the green wire test and I can disconnect and reconnect it without the pops.  I have have also observed the operation of the switch contacts under magnification, and as far as I can tell they open and close pretty much simultaneously.

So, before I start bending stuff, what is the best method of adjustment to get the BB-GN contacts to open first/close last?   

bump

[unbeldi]

Make sure it's the real cause.

You can test the contacts sequence by placing paper between the contacts that should close last, and pull out the paper after the first set has closed.


BSP Section C38.549 Issue 3 March 1960 (Telephone Sets — 300 Series; Maintenance) contains maintenance information for 302s.  It's probably not detailed enough though for this case.

[NorthernElectric]

You can test the contacts sequence by placing paper between the contacts that should close last, and pull out the paper after the first set has closed.


BSP Section C38.549 Issue 3 March 1960 (Telephone Sets — 300 Series; Maintenance) contains maintenance information for 302s.  It's probably not detailed enough though for this case.

Thanks.  I tried your paper test (so simple I don't know why I didn't think of that  ) and the pops did not occur while doing it.   I checked out the BSP and you're right about the lack of detail.  But the paper test gave me the confidence that I was on the right track, so I proceeded to bend the heavy plate between the G-Y contacts slightly to the right to time the hookswitch (photo attached).  Keep in mind this is an NE 352.  Orientation of contacts would be 90 degrees rotated in a 302.

After resolving the hookswitch pops, I moved on to the dial.  As this phone was an assembly project, I had previously swapped the sticky dial from the metal 302 I bought recently into this phone to get that phone working.  I had cleaned and lubricated the dial before completing assembly of the 352.  I was also getting some dial pop out of it, though not quite as severe as the hookswitch pop.  So I took a stab at timing the dial contacts from advice I found here.  Though it took a bit of doing, I believe I have achieved success!  The phone now sounds normal going on and off hook, and also dialing.

[unbeldi]

Excellent!