Bell(Canada-Northern Electric) 554 Tel Touch -cannot break dial tone

[MyNortelPhone]

Here's my story ...

I have a Bell (Northern Telecom) wall mounted touch tone phone. It looks like this:



I removed the cover plate and the phone is marked with what I believe is the model number: 554 A/B.


Back History

Phone was working before, my in-laws  replaced it - sticky button. Found a PDF on the dial with exploded diagram (ITT - Tel Touch pushbutton dials #27, 32, & 36).
I cleaned the handset and removed the "Tel Touch" pad for cleaning. Took apart the keypad  down to the cranks. I didn't touch any of the spring assemblies for DTMF.  Figuring the stickiness must be on the buttons or button/springs - so I cleaned those up and reinstalled. Unfortunately, I didn't note the mesh pattern (back of the push button assembly) of the springs assembly (part #28) with the attenuator slide (part #10).Tried my best (various combos) as they was only 2 levers (long lever and a spring lever), a plastic film (probably an insulator) and the slide had 4 open spaces.

The "PDF"  noted that "the top tooth goes above the top long flat spring" so that must mean the the first long spring fits in the second opening of the slide. Then the manual states "Each successive tooth goes above the subsequent long flat spring - I don't have an more long levers to deal with. So I'll ignore this statement. Manual then states "the fourth tooth engages the stiffener spring of the Spring Assembly - OK that's my other spring lever.



I think I got it setup correct.

So when I tried to make a test call ... I could not break dial tone.

Testing the phone
Pressing the number keys produces various DTMF. They seem to sound correct. The cranks are engaging the various springs on the assembly plate. I read that pressing 2 buttons  on the same row simultaneously should produces a single touch. OK for me. Pressing 2 buttons on the same column also produces a single touch. OK too. None of the buttons pushed individually or in combination will break the dial tone. Also I can't hook dial but later read that could be due to the setup of the provider. Read it could also be due to switched ring and tip wires but that didn't resolve the problem.

Testing the line,
When a call is incoming, this phone rings. When the line is engaged with other phone, when I pick up my receiver I can hear the conversation. I tried hooking up another phone to this jack ,,, all is good - no problems. So I believe the issue is with the 554 phone and not the line.

Now I'm think it must be with the DTMF generator. It must have gotten jostled when I removed it out for cleaning.

To test this thought, I went online to a DTMF tone generator, placed the phone receiver next to the speaker and tried dialing my cellphone. Numbers was a combination 1, 5, 7, 9, 0. It rang my cellphone. So that must be it!

Using Advance Spectrum Analyzer PRO, I place my PC mike to the receiver ear cup and noted the following frequencies.

Working phone (Northern Telecom Jazz400)    #1             freq 689 & 1.2 kHz; #2              freq 689 & 1.3 kHz
Problem phone (554)                                         #1                           same       , #2                      same



    (pressing both #1 & #2, #2 & #3 at the same time gives me just a 689 Hz signal)



Reference: BSP                                                 #1             freq 697 & 1.209kHZ, #2           freq 697 & 1.336 kHZ

So  what gives? I'm completely baffled. The tones from both phones are the same. I read something about a twist in the frequency ... could that be it?

Any suggestions would be greatly appreciated.

[andre_janew]

It could be that the polarity is wrong and that you'll have to swap the red and green wires on the line cord.

[Key2871]

Yup I would also say the same. That's a polarity sensitive dial. Another thing, some had contacts on the back to connect a hook switch lead to as well.
Useually it was the brown lead that connected that and the Green lead as well, providing the dial had two points. I just don't recall which was which.
It's been a while so don't quote me on that. But if those are not connected the polarity guard will not work. And in some cases neither will the dial.

Assuming that your receiving tones in the receiver.

[MyNortelPhone]

It could be that the polarity is wrong and that you'll have to swap the red and green wires on the line cord.

Tried that earlier (swap tip and ring) ... didn't help. In either case, the tone generation still worked.

[MyNortelPhone]

Yup I would also say the same. That's a polarity sensitive dial. Another thing, some had contacts on the back to connect a hook switch lead to as well.
Useually it was the brown lead that connected that and the Green lead as well, providing the dial had two points. I just don't recall which was which.
It's been a while so don't quote me on that. But if those are not connected the polarity guard will not work. And in some cases neither will the dial.

Assuming that your receiving tones in the receiver.

No connections were disconnected. There are 4 wires from dial to "block", red, white, orange with black stripes, and white. The orange with black is soldered to the block along with a grey with brown patches wire from the hook switch.

The only wires that I touched were the red and green (ring & tip) so that I could easily test the phone without hanging tte phone back onto the wall.

I can hear the tones being generated from the receiver. The hook switch does hang up the phone.

P.S. Although I have a tool in the coil ... I didn't adjust the screw. Just working on the tool head shape just in case.

[Key2871]

That's quite a differant dial, I've not seen one like that before.
Have you tried the internet for a diagram for that dial in that phone?
I've seen touch tone versions of the 554 but not using a dial like that.
I was thinking it was a normal ITT touch tone dial with the bezel that goes over the pad.
But that actually looks roundish type of dial.
Sorry, I haven't a clue what wires would connect to get it working.
I saw a screen shot of what I'm guessing is a tester with tones input.. Do they line up with parameters?

[TelePlay]

I saw a screen shot of what I'm guessing is a tester with tones input.. Do they line up with parameters?

Combined images for comparison.

[MyNortelPhone]

That's quite a differant dial, I've not seen one like that before.
Have you tried the internet for a diagram for that dial in that phone?
I've seen touch tone versions of the 554 but not using a dial like that.
I was thinking it was a normal ITT touch tone dial with the bezel that goes over the pad.
But that actually looks roundish type of dial.
Sorry, I haven't a clue what wires would connect to get it working.
I saw a screen shot of what I'm guessing is a tester with tones input.. Do they line up with parameters?

Actually the round bezel pops off if you undo the 2 corner screw clips. The dial is actually squarish. Very much like the one shown on the website telephonetribute for the ITT Tel-Touch pushbutton dials, #27, 32 & 36 (TIMM-2). I'm pretty sure the wiring is correct as it was working before the cleaning.

Those are not tester tones screenshots ... they are actual recordings of the DTMF generated by my trouble phone. They are fairly close to the recommended frequencies. What is funny is that my other phone generates the same peak frequencies and it dials out OK. 

[MyNortelPhone]

Combined images for comparison.

Thanks! Did you just do a C&P to line them up?

[TelePlay]

Thanks! Did you just do a C&P to line them up?

Yes, in Adobe PS.

[MyNortelPhone]

I recorded and analyzed all of the DTMF tones and compared them to a known good phone. All of the Hi tones were the same (1.2, 1.3 & 1.5). The lo tones were the same for rows 1, 2, 3 & rows
7, 8 & 9. The exception was row 4, 5 & 6; the bad phone was at 753 Hz and the good one was at 775. BSP has the value recommendation of 852 Hz.  So after much thought, I decided to try my hand at adjusting the coils.

I flipped the dial over and noted that the coil marked with the yellow stripe was a tad loose (see earlier picture). Thinking ... hey that much be the LO frequency coil. This model from Nortel does not have the triangular head bit that the WE used, instead they used a hex (allen) wrench -5/64 size. I read that some members were able to wittle a piece of wood into the proper shape ... so why not a hex shape instead. To make a long story short, I did fashion a piece of wood and rammed it into the screw head. The screw was turning a bit but only if I pressed hard down on it. Then it happened!! The screw felt like it broken the threads and bottomed down the hole. Sampling the tones ... the frequency changed ... the coil was the HI frequency. I was working on the wrong one.  Frequency dropped like 100Hz across the board.  Seeing that I messed up the HI coil ... might as well try my luck on the LO coil. Yes, I can confirm that the LO coil is the one marked with a white band.

So I have a few questions to ask ...
1. In the coil adjustment process ... is it only the screw that moves? The two pieces that make up the round coil stay in place? Originally I thought that the screw could wildly change the frequency but now I don't think that is so. Does one of those round coils rotate and the screw keeps that alignment?
2. How do I recover and repair the screw from the HI coil?
3. What would happen if I used my metal allen wrench in those coils?

As I wait for any suggestions ... I'm in the process of manufacturing a plastic tool head for that coil screw head. Since I now know its a 5/64 hex, I made a mold of the wrench head  and will try to press some molten plastic into it to make a tool.


To end on some good news ... a few of the number keys now breaks dial tone. So it must be DTMF related.

[RB]

What little I know...
The screw if that is the part inside of the coil, is a slug.
It moves up/down inside the coil. coil is stationary.
If you use a metal adjusting tool, you are adding to the coil,interfering with how it is made. don't do that.
We used what we called dittle sticks, you could buy them at radio shack.
you may still be able to find them online. they are plastic.

[MyNortelPhone]

What little I know...
The screw if that is the part inside of the coil, is a slug.
It moves up/down inside the coil. coil is stationary.
If you use a metal adjusting tool, you are adding to the coil,interfering with how it is made. don't do that.
We used what we called dittle sticks, you could buy them at radio shack.
you may still be able to find them online. they are plastic.

Thanks for the information. You got it right ... the slug (socket set screw) just goes up and down.  I don't know if I'm going to be able to find the dittle stick (learnt something new today) at RS. I'll see if my homemade tool works first.

[MyNortelPhone]

What little I know...
The screw if that is the part inside of the coil, is a slug.
It moves up/down inside the coil. coil is stationary.
If you use a metal adjusting tool, you are adding to the coil,interfering with how it is made. don't do that.
We used what we called dittle sticks, you could buy them at radio shack.
you may still be able to find them online. they are plastic.

I found this ...
https://www.tubesandmore.com/products/alignment-kit-gc-electronics-color-tvs

This link may help others who need something similar

I recall seeing this type of stuff in my youth when the Radio Shack catalogue was a big deal.

[MyNortelPhone]

...

As I wait for any suggestions ... I'm in the process of manufacturing a plastic tool head for that coil screw head. Since I now know its a 5/64 hex, I made a mold of the wrench head  and will try to press some molten plastic into it to make a tool.
...

The creation of the mold was good but the tool didn't successful.