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555 won't ring stations

Started by BruceP, April 08, 2013, 12:55:47 PM

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BruceP

I buzzed the lamp socket connections with power supply disconnected. Without bulb I got connectivity from supply +/- to one lead. Open across leads. With bulb in get the 46 ohms.

According to the schematic, the input AC runs through a switch on the optional crank generator(mine doesn't have one) to pins 13 & 14 of the 348A plugs, but I don't get connectivity or voltage there.

G-Man

That is incorrect.

Not all key systems ringing supplies are fused at the output, especially the small early kts supplies.

Most likely Northern suggested substitution with a fridge bulb only when their recommended ringing supply or a ringing supply over cable pairs was being used.

Their on-site supply would have had an output capable of most likely 15-20 Watts, far more than the 1 to 5 Watt outputs of most simple key system supplies.

BruceP

So far I've tried a '90s novelty phone, a 90's AT&T phone, and a '80s heavy old AT&T wall phone with real bell. What does bridged ringing mean?

G-Man

If the telephones you are using are 90's vintage then they are already setup for bridged ringing.

G-Man

Since you have ringing voltage inside the board as attested to the fact the attendant's buzzer is working, and assuming all of the straps on the ground terminals are in place, then the problem obviously lays elsewhere. If you are unable to trace it out through the schematics then it may be advisable to contact some of the telco pbx repairmen who reside on the TCI list.

G-Man

Bruce-

If your switchboard has never had the optional hand generator the ringing supply is routed through strapping option ZJ to terminals G and H of the multiple connections to which plug 348A makes connection through contacts 13 and 14.

G-Man

Try plugging into a station line using the left cord. Then press the left ringing key. This should be a direct route from the ringing supply to the plug. If ringing current does not appear, then try tracing it through the ZJ option straps for the hand-magneto. Does it look as if a magneto had ever been installed and possible that someone robbed it before you acquired the board? If so, then they may not have rewired it correctly.

BruceP


G-Man

Have you attempted to plug one of the left cords into a station jack and pressing its ringing key to see if will ring the telephone connected to that jack?
In case that doesn't work, shortly, I will attempt to upload a pdf of the ringing circuit if I can figure out how to do it.

G-Man

Here is a pdf showing the ringing supply path. This is from a drawing from Western Electric. It is interesting that the GTE drawing  that you obtained from the TCI Library is easier to understand...

G-Man

I don't know what types of test equipment you have at your disposal or if you feel comfortable troubleshooting while ringing current is applied to the circuit, but if I were attempting it I would do the following.

First, connect a meter or better yet, one wire from a test telephone to the G lead of the ringing generator.

Being very careful to not allow your hand or body to make contact with you test leads or any part of the circuit, take the second wire and briefly touch it to the supply side of the ballast/resistance lamp.

You should hear the telephone ring or your meter show ringing voltage.

Then touch it to the other side of the lamp and it should ring again.

Repeat this at each point of the circuit that you can access on up to terminal 14 or the 348A plug.

If you have ringing up to this point, reverse the process by disconnecting the test lead connected to the G terminal and reconnect it to the other (supply) lead from the ringing generator.

Then test each point of the circuit up to terminal 13 of the 348A plug.

Hopefully my instructions are not too confusing!   

marty

Hi All;
G man, Would the GTE document that is posted above, be of any help for me to locate where my wiring might be wrong or not connected, or Is there enough difference between the two boards, that it would not be of any help ?? I have also tried to locate any other GTE documents like this one and have had no luck..
THANK YOU Marty

BruceP

Quote from: G-Man on April 09, 2013, 02:05:21 PM
Have you attempted to plug one of the left cords into a station jack and pressing its ringing key to see if will ring the telephone connected to that jack?
In case that doesn't work, shortly, I will attempt to upload a pdf of the ringing circuit if I can figure out how to do it.


I just tried this and it doesn't ring.

BruceP

Quote from: G-Man on April 09, 2013, 02:39:20 PM
I don't know what types of test equipment you have at your disposal or if you feel comfortable troubleshooting while ringing current is applied to the circuit, but if I were attempting it I would do the following.

First, connect a meter or better yet, one wire from a test telephone to the G lead of the ringing generator.

Being very careful to not allow your hand or body to make contact with you test leads or any part of the circuit, take the second wire and briefly touch it to the supply side of the ballast/resistance lamp.

You should hear the telephone ring or your meter show ringing voltage.

Then touch it to the other side of the lamp and it should ring again.

Repeat this at each point of the circuit that you can access on up to terminal 14 or the 348A plug.

If you have ringing up to this point, reverse the process by disconnecting the test lead connected to the G terminal and reconnect it to the other (supply) lead from the ringing generator.

Then test each point of the circuit up to terminal 13 of the 348A plug.

Hopefully my instructions are not too confusing!   


No, they are great.
I got the test phone to ring from the other side of the ballast lamp, but not pins 13/14.
The lamp wires join a neatly tied bundle off to who knows where.
Thanks for the diagram showing the ZJ option straps, but where can I find them physically to test them?
I wish the schematic had wire colors, and/or there was a correlation to a physical picture/drawing.

This board was taken out of an office and put into a living room as furniture for 30 years. No one touched the wiring, I don't see anything cut or spliced.

It even has the 3 50-pin Amphenol(?) connectors attached. I have some of these cables (and will soon have a lot more) so I found where the stations were and wired up two phone jacks to two of the extensions. I have a LAN patch panel with the same cables I am planning to wire up my 30 stations to jacks on this panel.

I couldn't find any pins on the connectors that were through to the 24 VDC and 30 Hz AC supplies, or the trunks. I'll try again, but does anyone know exactly how the power was connected to the chassis?

poplar1

Here's an old thread on the 555. The picture in Reply #30 was provided by Davepei:

http://www.classicrotaryphones.com/forum/index.php?topic=4705.15

"C'est pas une restauration, c'est une rénovation."--François Martin.