old telephone repair
Posted: Wed Jan 23, 2019 11:44 am
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.
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. 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. 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. 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
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.
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. 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. 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. 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