Recent posts

#1

Key Systems (Electronic, 1A2 etc) / Re: "A" lead & hold control wi...

Last post by 5415551212 - Today at 07:02:12 PM

Thanks for confirming my understanding of the A-lead.
I am finally getting back to building up my key shoebox system along with one of Gregg's 'Seriss' 1A2 boards, and revisiting my idea for designing a modern line card, call it 400i (as I think H was the last revision).
I have ideas for about 5 different cards, but first want to make the most basic linecard.
However I am thinking of adding just one feature;
the card could also detect when other non- key phones 'upstream' from it go off hook, and then I was thinking it could also detect downstream by more precisely measuring loop current and changes in loop current.

#2

Technical "Stuff" / Re: The end of POTS?

Last post by poplar1 - Today at 05:35:01 PM

Mike, please post copies of these letters.

It seems AT&T has been trying  to no longer be carrier of last resort. Initially, they were asking state legislatures (not the PUC)  for the right to abandon copper landline service wherever there were alternative carriers. Now, it seems, they couldn't care less if subscribers are left with no alternative -- for example, where cell phone signals are not reliable or non-existent; where there is no decent internet; etc.

When I was installing and repairing phones for the State of GA, we had to provide 2 lines for fire alarms. One had to be dedicated and the other could be wired through an RJ31X jack so that the alarm system would have priority over voice calls. I'm not sure how the building owners (some space is leased rather than State-owned) can get a certificate of occupancy without these copper lines. Also, fax machines don't work on VOIP lines, yet faxes are required for certain medical documentation, because sending over the internet or email is not considered secure.

The discontinuation of landlines in the United Kingdom has apparently been pushed back to 2026, because of so many complaints. Many existing alarm systems, medical pendants, etc. have stopped working when switched to VOIP...

#3

Key Systems (Electronic, 1A2 etc) / Re: "A" lead & hold control wi...

Last post by poplar1 - Today at 05:00:06 PM

Question for those running key systems:
Say you have two regular key phones on the same extension off hook and one presses the hold button and hangs up a single phone what happens?

Line will not go on hold since at least one phone is still off hook = A lead is still shorted to A1 lead at the line card.

Can you place a call on hold if another key phone is off hook?

No

The "A" lead from what I understand allows a call to be placed on hold and tells the lamp for that line to wink.

Pressing the hold key removes the short between A lead for the active line and the A1 lead common to all lines on the set. This must occur *before* tip and ring are disconnected. (When hanging up on a call you don't want to place on hold, the tip and ring disconnect first. This happens with the hookswitch contacts only. If the hookswitch contacts are out of sequence -- that is, the A/A1 opens first -- then the line will go on "false hold" condition since this was not the intention of the user.)

If a phone extension goes off hook the line card senses loop current thru the card and "A" lead connects to DC 'ground' (call in progress) via the hook switch in the phone (or via an "A-lead adapter" for a non A-lead compatible phone).

Correct

The 3 states of hold as I understand it are
1) When hold is pressed for a moment on a key phone it disconnects the "A" lead from DC ground but not the tip and ring .The line card still senses normal 'loop current' but now A lead is floating. However this would only work if the all the "A" leads were a series circuit correct? If not then any other phone off hook would keep the A lead grounded.

In 1A1 or 1A2 Key, the A/A1 and Tip/Ring are separate. The A leads for each line are in parallel to whichever phones pickup that line. Yes, any phone off hook on the same line will keep A lead grounded.

2) When the hold is released, it mechanically releases which ever line button is down on the set, removing the loop current. But with another extension off hook there would still be loop current flowing thru the line card so the call would not go on hold ?

It would not go on hold, not because of central office line current going through the line card, but  because A is still shorted to A1 in at least one set.

3) With all phones hungup the "A" lead is floating or has a voltage potential to ground (via a relay coil or whatever circuit in the line card).
Thanks

With all phones hung up, the short between A of a particular line and A1 is missing. Therefore, the line/busy lamps are dark on all sets.

#4

Key Systems (Electronic, 1A2 etc) / "A" lead & hold control with 2...

Last post by 5415551212 - Today at 02:14:30 PM

Question for those running key systems:
Say you have two regular key phones on the same extension off hook and one presses the hold button and hangs up a single phone what happens?
Can you place a call on hold if another key phone is off hook?
The "A" lead from what I understand allows a call to be placed on hold and tells the lamp for that line to wink.

If a phone extension goes off hook the line card senses loop current thru the card and "A" lead connects to DC 'ground' (call in progress) via the hook switch in the phone (or via an "A-lead adapter" for a non A-lead compatible phone).

The 3 states of hold as I understand it are
1) When hold is pressed for a moment on a key phone it disconnects the "A" lead from DC ground but not the tip and ring .The line card still senses normal 'loop current' but now A lead is floating. However this would only work if the all the "A" leads were a series circuit correct? If not then any other phone off hook would keep the A lead grounded.

2) When the hold is released, it mechanically releases which ever line button is down on the set, removing the loop current. But with another extension off hook there would still be loop current flowing thru the line card so the call would not go on hold ?

3) With all phones hungup the "A" lead is floating or has a voltage potential to ground (via a relay coil or whatever circuit in the line card).
Thanks

#5

Technical "Stuff" / Re: The end of POTS?

Last post by MMikeJBenN27 - Today at 02:11:38 PM

Last month, it was in the paper here in Northern California that ATT was again petitioning the PUC to end the requirement that they provide home telephone service, and I received a letter from the phone company as well stating that very same thing.  I just received an other letter from them telling me that I can keep my home phone service with no changes, but they are going to be offering me "alternatives" that are "better", (better for their profits, not better for me), and that regulations need to change, so hopefully that means the PUC has denied their petition.  I hope I am not speaking too soon. 

Mike

#6

Telephone Troubleshooting and Repair / Re: WE 554 won’t ring

Last post by keithi70 - Today at 02:04:33 PM

If you put your finger on the clapper, do you feel any movement?

You can temporarily disconnect the blue dial wire from RR. Then, listen in the receiver while the phone is supposed to be ringing. Do you hear anything?

I'll put my finger over the clapper later and see if I feel anything. I'll try your blue wire suggestion as well.

#7

Telephone Troubleshooting and Repair / Re: WE 554 won’t ring

Last post by keithi70 - Today at 02:03:18 PM

If you connect another ringer, does it ring?  Perhaps the Telo device stopped providing ringing current.

Larry

I literally just bought another rotary phone yesterday - a desktop WE 500 - but I'm waiting for the connecting wire I ordered to get here so I can wire it up. I bought it, among other reasons, to see if it rings or not.

#8

Phonographs, Typewriters, Vacuums, Calculators, Juke Boxes, Slot Machines & Cameras / Re: Bell & Howell 708 Headline...

Last post by Westrex - Today at 01:15:20 PM

Before you install the lens, remove the bulb without getting fingermarks on it. Get the fan going first, motor bearings probably need oil. Those little slide projectors get dangerously hot.
You may be better taking Sunset 12's deal.

I got the fan running and it works well, and the bulb is easy to remove (see manual photos). The condenser is held in with some tabs that you can push out of the way to take out and install the new condenser.

#9

Telephone Troubleshooting and Repair / Re: WE 554 won’t ring

Last post by poplar1 - Today at 01:05:18 PM

If you put your finger on the clapper, do you feel any movement?

You can temporarily disconnect the blue dial wire from RR. Then, listen in the receiver while the phone is supposed to be ringing. Do you hear anything?

#10

Telephone Troubleshooting and Repair / Re: Stromberg Carlson wont dia...

Last post by bcarolla - Today at 12:49:00 PM

There is no model information stamped on any of the bases on the 5 phones I have that all act the same. I think I am giving up on these and moving on. Thanks for all the help.