News:

"The phone is a remarkably complex, simple device,
and very rarely ever needs repairs, once you fix them." - Dan/Panther

Main Menu

400D Relay L connection?

Started by AMCer, April 30, 2013, 12:48:37 AM

Previous topic - Next topic

AMCer

I'm trying to figure out how relay L is wired on a 400D card.  The schematic shows:



What are pins 1,3,4 & 6  and what does P-59  & S-755 mean?

rdelius

I believe 1-3 is one coil and 4-6 is another coil and the larger numbers are the resistance (impedance).And both are part of relay L

AMCer

Why are there two coils in it?

G-Man

They are for line sensing and supervision.  A detailed description can be found in the CD for this card and while I would have to look at it to verify, typically the P and S stands for primary and secondary windings.

There may be one located in the TCI Library. If not a request on the TCI list for scanning it may be in order.

G-Man

Quote from: G-Man on April 30, 2013, 05:08:33 PM
They are for line sensing and supervision.  A detailed description can be found in the CD for this card and while I would have to look at it to verify, typically the P and S stands for primary and secondary windings.

There may be one located in the TCI Library. If not a request on the TCI list for scanning it may be in order.

Also, perhaps not as detailed as a CD, the Bell System Practice containing for the 400D may also contain an easily understandable circuit description. Again, there should be a scan of it in the TCI Library or if not a request made on the TCI list often will yield a copy.

AMCer



"In the drawing, I show my line circuit with a conventional two-winding line relay L having a low resistance hold winding LH and a higher resistance ring winding LR. The relay operates on energization over either winding to close its single pair of contacts L1 within the lower half or D.C. logic portion of the circuit."