Pulse dialing is too fast

[Timusius]

It works!


I was sure that the phones were ok, (and that Denmark probably had systems that accepted 15PPS), but your many comments on 10PPS being the standard, made me think twice.

Then combined with the help from TelePlay ...

All rotary dials have a mainspring, gears, a speed governor and leaf switches. How that all goes together depends on the manufacturer's propriety, patented design.

... I decided to open the phone again, and look a bit at the speed governor. While it was in fact extremely difficult to get to, I was quickly able to determine that the "governor arms" were not moving at all. So it was not doing any "braking" at all.

I added a tiny dap of oil on the governor in places where it seemed it could use some.... and now the phone suddenly works as it should.

It's not 100% perfect (yet), but I am able to call my short numbers (like 422, 155  etc.) and get them to work almost every time.

Mystery solved!
These phones have been standing still for many years, and they probably all dried up. And by random design they all run around 15PPS when the governor is unable to do it's job.

You guys are awesome! Thank you ALL for your help!

[TelePlay]

... I decided to open the phone again, and look a bit at the speed governor. While it was in fact extremely difficult to get to, I was quickly able to determine that the "governor arms" were not moving at all. So it was not doing any "braking" at all.

I added a tiny dap of oil on the governor in places where it seemed it could use some.... and now the phone suddenly works as it should.

It's not 100% perfect (yet), but I am able to call my short numbers (like 422, 155  etc.) and get them to work almost every time.

Good to hear.

Keep in mind that the speed of the dial changes from the first digit pulsed to the last one pulsed. If you dial "0", the dial speed will be faster for 0, 9, and 8 and it will be for 3, 2 and 1. As the dial spring unwinds, there is less "force" left in the mainspring as it approaches the last few digits, so the dial slows down.

It's not much of a speed change but it is there in every dial. Assuming the dial speed is 10 PPS and the Break/Make ratio (percentage) is 60/40 on a perfect dial. The central office equipment is not looking at, reading dial speed. It is looking at the finite amount of time the line is open, the break period, and the make period. On a perfect dial that is 0.06 seconds of break and 0.04 seconds of make.

If the dial speed is fast, say 20 PPS, the break period is reduced to 0.03 seconds and the make period is then 0.02 seconds. In this case, the central office does not recognize the 0.03/0.02 break/make sequence even through the Break/Make ratio is still 60%/40% and the central office sends back a dialing error message.

Since you discovered your governor brake wings were frozen open from lack of lubrication, the governor was not working and the dial was turning at its full speed, something greater than 11 PPS. The faster speed was reducing the Break/Make times to something less than 0.06/0.04, something your central office did not recognize.

Now, with some lubrication on the brake wing pivot points, the brakes are working but still not fully. As such, the lower numbers (1,2,3,4) are generating break/make times that the central office is reading but the higher numbers (0,9,8) are not. The faster dial speed of the higher numbers is creating break/make intervals on you dial not recognized by the central office but as the dial slows and gets into the 4,3,2,1 numbers, the break/make time periods are in spec (because the dial speed has slowed) and are now recognized by the central office. So, right now, your dialing 3 would be recognized but 9 would still not.

I expect with more small amounts of lubrication on the governor brake wing pivot points and working the dial to get the lubrication into the pivot points, the brakes may work even better and slow the dial speed to a rate that will generate an acceptable break/make time periods for the 0,9,8 numbers as well (all the numbers).

It's the combination of dial speed and hardware that creates the break/make pulses in the leaf switch that generates the break/make times needed by the central office to see which number is dialed.

The above is deep in the mechanical weeds but that's how a dial works and explains both your problem and what you have discovered as the solution.

[5415551212]

I am glad its working, another old phone connected back to the network.
Since they were giving you a support be sure to follow up with Grandstream and link them to this forum.