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Fixing DTMF on a WE 2500

Started by Rurorii, March 04, 2023, 05:56:03 PM

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G-Man

#15
Even though the model number of the dial or vintage of the telephone was not provided, I suspect the dial is of the older variety with ferrite coils being used to generate the various frequencies.

As a point of reference, you should first call Testcode at (804) 222-1111, dial option 2 (DTMF test), then at the tone input 1234567890* and wait for the results.

If you find that your dial does need adjustment, reference the jpeg that I have included below. Note that an audio frequency meter instead of the referenced oscilloscope should be used instead. A number of standard DMMs are now capable of measuring audio frequencies.

"Reading should be within 1.5% of the listed frequencies."


You will need to purchase or fabricate an adjustment tool to tune the coil's ferrite slugs. Be advised that the slugs can be brittle and if stuck, may shatter when too much force is applied.

If you are out of your comfort range, then sending it to Steve Hilsz for repair at a very nominal charge is another option.

"Thinking is hard work, which is why so few people do it!" - Henry Ford


G-Man

I forgot to add that the dial's contacts may also be in need of cleaning.

First try using a piece of high quality archival paper, such as "Bell System Bond" or other quality letterhead with low sulphur content, to be drawn though them.

 A business card printed on similar quality paper may also be used, just don't allow the printed portion to be drawn through the contacts.

Using average paper invites reoccurring problems to popup from time-to-time.


paul-f

Quote from: G-Man on March 07, 2023, 02:12:18 AMIf you find that your dial does need adjustment, reference the jpeg that I have included below.


What's the source document for this page?
Visit: paul-f.com         WE  500  Design_Line

.

poplar1

Quote from: G-Man on March 07, 2023, 02:12:18 AMYou will need to purchase or fabricate an adjustment tool to tune the coil's ferrite slugs. Be advised that the slugs can be brittle and if stuck, may shatter when too much force is applied. [/size]


With a maximum deviation of 0.17%, I believe we have already ruled out the necessity of adjusting the frequencies.

G-man: Any other component that you might think is failing?
"C'est pas une restauration, c'est une rénovation."--François Martin.

G-Man

Quote from: poplar1 on March 07, 2023, 03:17:29 PMWith a maximum deviation of 0.17%, I believe we have already ruled out the necessity of adjusting the frequencies.

G-man: Any other component that you might think is failing?
That would indicate there is no problem with his dialpad and everything should be working well.

However, since it still does not play well with the interface, then other factors are at play.

We still have not verified whether it is the older or the later crystal controlled generation circuitry.

I would consider checking the caps but the data that was provided indicates the dialpad should be working ok.

This brings everything back into question such as if the results of recording methodology (such as through a laptop microphone) is accurate or if the data were properly transcribed. While I suspect that it was, in lieu of anyone else presenting an answer, it still would not hurt to take a second look at everything.

And I also doubt that there is a problem with the skew/twist rates, but who knows at this point?

It certainly would not do any harm to simply call the test number that I provided to see what those results are.

Since as of yet no one else has advanced a theory as to why it fails to work properly, then performing the above actions will not do any harm.


TelePlay

Wouldn't it be possible to place a buttset on the line after the wall jack (behind it) to listen in on the line for the handset being lifter (line going off hook and the dial tone starts) and then to hear the tones of each number being dialed?

Wouldn't no dial tones heard in the buttset point to a problem between the DTMF pad and the line cord?

Rurorii

The only time I changed the wiring so far is switching the polarity, I since switched it back.
Neither did I change any wiring on the other phone, but I don't still have it...

G-Man

#22
Quote from: TelePlay on March 07, 2023, 08:27:10 PMWouldn't it be possible to place a buttset on the line after the wall jack (behind it) to listen in on the line for the handset being lifter (line going off hook and the dial tone starts) and then to hear the tones of each number being dialed?
Wouldn't no dial tones heard in the buttset point to a problem between the DTMF pad and the line cord?
Good idea TelePlay but I doubt that he has access to a buttset and he states that the instrument functions just fine since it rings and talks up ok.

He also can hear the tones in the receiver and apparently it is sending them since he can press the buttons and a caller can hear them.

It would still be nice if he would let us know the following:

  • Model number of the dial and/or photos showing the markings on it
  • Vintage of the set and number on the network; photos if possible
  • Call the test number* that was provided earlier and let us know what the results of the DTMF test are.

*Testcode at (804) 222-1111, dial option 2 (DTMF test), then at the tone input 1234567890*# and listen to the results.

Rurorii

Sorry for missing messages yesterday, I think I forgot to refresh the page...

- I called the provided test number and it was able to detect the numbers I dial. This initially makes me fear that its possibly an issue with Xlink gateway so I'm going to find another 2500 to see if its only a problem with this phone.

The dial is labeled "35Y3D  12-79"

TelePlay

Or find someone who has a POTS landline and see if it works on it.

poplar1

Quote from: Rurorii on March 04, 2023, 05:56:03 PM(Side note: I don't actually have a telephone service. Instead I am using an Xlink Bluetooth gateway, but i'm pretty sure this is not the issue as another phone worked fine with it)


I guess some of us -- me included -- assumed that the "other phone that worked fine" was also Touch-Tone. Was it in fact a rotary phone?
"C'est pas une restauration, c'est une rénovation."--François Martin.

Rurorii

no, it was another touch tone