old telephone repair

This is where we talk about testing, measuring and repairing things. Sometimes we have to repair the equipment we use to test, measure and repair other things. It's an endless cycle of fixing the broken things we need to fix other broken things.
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JR.
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old telephone repair

Post by JR. » Wed Jan 23, 2019 12:44 pm

OK, i'll stop calling repairs "entropy" as that seems like code for random blogging (which I am guilty of).

I mentioned telephone repair in that other thread that shall not be named again here, but that drama is far from over and a little embarrassing. :lol:

The problem was my old (purchased from phone company in 1980s) standard old POTS telephone set was unreliable about tone signaling. Being old and lazy I decided to buy a used phone from EBAY for <$20. Of course karma punishes all such sloth and that used phone has a bad #4 button. :o Throwing good money after bad, I purchased a new replacement touch tone keypad...

I tried connecting the wires by using same color code of old wires but the old phone keypad had two extra wires. :roll: Of course it doesn't work at all, so actually moving backwards from just one bad button.

The vendor I bought the replacement keypad from is trying to be helpful but he keeps asking me for a high resolution photo, and my cheap POS camera refuses to deliver anything useable. At this point I don't see buying a better camera after helping my endodontist make a down payment on a new bass boat (root canal... then I have to pay for a crown, but this too is karma for not visiting my dentist in over a decade).

Finally this morning I found a schematic for the used phone set (ITT 2500?). I already found what looked like errors comparing phone to old WE 500 series schematics. This new schematic looks more promising so back to the bench.

===

In the meantime I have already repaired my original misdialing phone... the old WE/Bell design is robust and relatively easy to service. The 3x4 matrix of keypad switches are all located around the periphery of the keypad. Further the switch design looks robust, with a sharp triangle shaped contact on one side with a scrubbing action when pressed. I used some very fine grit sand paper (#400) on the one balky switch. This was probably the first time it was cleaned in over 40 years. :lol: The flaky ITT touch tone keypad appears to have a mechanical issue limiting travel of the row switch. Pushing any one of three buttons in same row should close the row switch and #4 just isn't getting it done, 5 and 6 are switching the row switch, 4 is flaky.

More later... I don't really need another working phone, but at this point it is a point of honor. Old phones are not rocket science or shouldn't be. Now that I have actual schematic (I hope) I can check it better.

JR

PS: Did I ever mention that I love the WWW, found a great resource with old phone data.. here is my specific phone set schematic https://www.telephonecollectors.info/in ... -k-2500-tl
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JR.
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Re: old telephone repair

Post by JR. » Wed Jan 23, 2019 3:24 pm

Well found one problem... one wire from the earpiece speaker, was plugged into an unused terminal. That was one of the two extra wires missing from the replacement keypad was plugged there.

Still not working, yet. :(

JR
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Re: old telephone repair

Post by mediatechnology » Wed Jan 23, 2019 4:11 pm

Does the keypad in the WE Bell instrument have the tapped ferrite inductor?
If so it is old.
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Re: old telephone repair

Post by JR. » Wed Jan 23, 2019 4:50 pm

mediatechnology wrote:
Wed Jan 23, 2019 4:11 pm
Does the keypad in the WE Bell instrument have the tapped ferrite inductor?
If so it is old.
The old WE/Bell unit is put back together now.

The squirrelly touch tone keypad from the old ITT had two big honking ferrites hanging off the back. The replacement keypad is solid state,,, no ferrite.

I notice some free travel in the non-working button that the other ones don't have. So I am almost tempted to take it apart to fix the mechanical flaw.... but not tonight. :lol:

JR
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Re: old telephone repair

Post by mediatechnology » Thu Jan 24, 2019 6:20 pm

For someone wanting to use one of those wired antique phones on the Verizon network can use the NovaTel T1114.

Image

I have one for home POTS service and backup internet.
It's analog port provides cellular dial tone for our wired and wireless DECT phones.
The Ethernet port serves as backup internet if the cable system is down.
It also has a WiFi access point.

Touch tone only. Pulse dialing phones don't work though so really old antique phones can't dial.

Verizon don't offer the NovaTel T1114 anymore but they're available on Amazon and can be ported to Verizon.
We moved our legacy analog POTS from AT&T a couple of years ago and the savings have been huge.
I think I'm paying $10/month for this line now versus about $80 before.

(I just re-read this. Pretty convincing spammy-sounding.)
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Re: old telephone repair

Post by billshurv » Thu Jan 24, 2019 6:51 pm

This has reminded me of one thing that I never got about America as a kid. In UK we kept rotary dial phones all through the 70s and into the 80s as we still had a lot of strowgers in use at the time. America seemed so advanced on the TV as everyone had push buttons and yet they had to call the operator to make a long distance call. I could dial the world with my old rotary!

When I moved to Chicago to help roll out a cellular network in 97 I then realised the true horror of American telecomms!

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Re: old telephone repair

Post by JR. » Thu Jan 24, 2019 8:11 pm

billshurv wrote:
Thu Jan 24, 2019 6:51 pm
This has reminded me of one thing that I never got about America as a kid. In UK we kept rotary dial phones all through the 70s and into the 80s as we still had a lot of strowgers in use at the time. America seemed so advanced on the TV as everyone had push buttons and yet they had to call the operator to make a long distance call. I could dial the world with my old rotary!
I continue to be amazed about what people from outside America think it is like.

I recall back in the 60s/70's hackers, perhaps the original hackers, were making "blue boxes" to mimic the telephone long distance network signaling tones to make long distance calls without paying. I somehow doubt they used operator assistance. :lol:

When I moved to Chicago to help roll out a cellular network in 97 I then realised the true horror of American telecomms!
A lot of horrors in telecom... The US government trust busters broke up Bell Telephone , because they were arguably too big, killing bell labs one of the premiere R&D facilities in the world at the time. Good job government, you showed them... :oops:
===

I am struggling with a myriad of different versions and lack of clean documentation (for an old ITT phone I purchased cheap/used). I suspect this is one of several copies of the basic WE design. I have already found two different variant ITT schematics and neither one is this exact phone. Then I have an aftermarket replacement touchtone keypad.

I bet an old phone technician could figure this out (not rocket science), but not simple for me. I am about ready to stick a fork in this repair attempt, it really isn't worth my time any more... I already repaired the phone I actually need to work. I am thinking about making this one an answer only set. I could use a dumb phone in the bathroom to answer awkwardly timed calls. :lol:

I have other projects I want/need more backing up in the queue.... 8-)

JR

PS: My POTS set connects to a phone line coming from my DSL modem so rotary might not work for me either, but I haven't needed rotary for a while.
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Re: old telephone repair

Post by billshurv » Fri Jan 25, 2019 6:43 am

I have read about phone phreaking (and the cap'n crunch whistle they used). The called party pays setup with mobiles was a little silly. to a European mindset. I remember when i got my first mobile in US I had to decide whether to get a number local to home or local to the office. And fly to Dallas and discover a call back to Chicago was $1.29 a minute!

AT&T really stirred that pot in 1998. Their banner adverts on the highways was a giant Nokia phone with a stars and stripes cover. Oddly for a while people thought Nokia ran the network!

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Re: old telephone repair

Post by JR. » Fri Jan 25, 2019 9:04 am

Woznizk, the actual engineer behind early apple computer started out selling blue boxes. I don't think it was illegal because nobody thought to make it illegal, but it was theft of services.

JR
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Re: old telephone repair

Post by billshurv » Fri Jan 25, 2019 9:24 am


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