If you restore antique phones, you probably at one time or another rebuilt a phone and installed a dial that wasn't properly adjusted. There's nothing more frustrating than putting hours of work into a phone, neatly positioning each wire, aligning the slots in the screw heads so they face in the same direction, only to find the dial doesn't operate properly after the phone is completed.
If you restore antique phones, you should have test equipment to measure 'Pulses Per Second' (PPS) and 'Percent Break' of the dial's pulsing contacts. Unfortunately, this usually isn't the case.
This article describes building a very simple and inexpensive device for testing a dial to see if it operates within spec - BEFORE you install it into a phone.
This isn't 'rocket science'. It's a simple test cable that connects the pulsing contacts of the unknown dial in series with one side of a phone line and any telephone, in a physically neat way. It can be built in a few minutes very inexpensively.
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What You'll Need
1- 1/4 Modular phone cord with lugged ends
2- Spade to spade jumpers
Or spade to alligator clip jumpers-see below
1- RJ-11 baseboard phone jack
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Construction
Cut off the Yellow
and Black lugged leads from the cable and RJ-11 phone jack.
Connect the RED lugged leads from the cable and
the RJ-11 phone jack together using a screw position.
Connect one of the lugged jumpers to the Green
lugged lead of the cable using a screw position.
Connect the second lugged jumper to the Green
lugged lead of the RJ-11 phone jack using a screw position.
Face the lugs of the two jumpers into the
box.
They are shown facing outward to simplify the
picture.
Strain relief the cable and the two jumpers,
then run them out of the slot in the bottom of the RJ-11 box.
Snap the cover on the box.
That's it!
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Operation
Plug any telephone into the RJ-11 phone jack.
Plug the cable into a phone line.
Connect the two lugged wires to the pulsing contacts of the dial under test.
Take the phone off-hook to bring up a dial tone.
Dial your cell phone or your mother-in-law's phone number with the dial you're testing.
If it dials properly you're in business.
If it doesn't, aren't you glad you found out BEFORE you wired it into the phone?
If most of the phones you work on have lugged dial leads (Western Electric 500 desksets, etc.), you probably would want to make the two jumpers with alligator clips on one end instead of lugs.
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Below is a Western Electric #5 dial being tested.
The jumper leads are connected to the pulsing contacts 'BK' and 'Y' of the dial.
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Below is the top of a payphone being tested.
Connect the jumper leads to transfer contacts 'Y' and 'R' of the payphone's top.
Take the phone off-hook to bring up a dial tone.
The electromagnet on the coin track should energize when the handset is lifted.
Make a call using the dial in the payphone's top.
If the call goes through, deposit a nickel and a quarter while listening in the handset of the phone.
Both you and the party you called should hear the bell and gong when the coins are deposited.
This tests the payphone's dial, electromagnet and coin microphones all in one shot.
Not bad for a gadget that takes a few minutes to build and costs practically nothing.
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Dial Adjustment
If you find a dial that isn't working and you don't have the necessary test equipment to measure 'PPS' and '% Break', it's not a good idea attempting to adjusting it.
You would be working blindly.
You might consider sending it for repair or adjustment to:
