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Getting A Barely Audible Dial Tone on a 2554BMPG

Started by Rotorman, May 10, 2019, 08:23:51 PM

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Rotorman

Have not worked on touch tone phones before, and trying to sort out a very faint dial tone on a flea market find.  I found the schematics baffling, and wondered if there's a likely solution to a very weak dial tone on the 2554BMPG.  I changed handsets and have the same problem.  Touch tone sounds come through loud and clear, and the phone does ring on incoming calls.  Wondered if there's an adjustment for dial tone volume on these sets, or if there's a wiring problem.  Perhaps all spade lugs need a good cleaning?  Any help appreciated.   

Key2871

On the older sets mechanical dials were used, those had contacts on the back that shunted the receiver to turn down the tone volume in the receiver. I don't recommend trying to clean or adjust anything as you can really mess up the dial.
What I've done before is to hit the buttons hard repeatedly. Not hard just push those buttons and it's possible that it will bring back the tone sound. But your probably going to have to get a new dial for it.
I have a H2 dial, looks the same, just has the short travel buttons. Will provide the wiring connections for it as well.

I had a few with that problem before, I tried cleaning and adjusting the switches, but that was not easy to do.
Send me a pm if you want the dial, postage only cost.

As for the phone not ringing try providing tip, green wire to the yellow or ground on the network.
Or try moving the black ringer lead to L1 on the network.
A picture of the network and ringer leads and post them here will help too.
Good luck.
KEN

Rotorman

There's no problem with the keys on the key pad, and I can hear the tones through the handset loud and clear when they are pressed.  It's the dial tone (indicating service) when the handset is lifted off the hook that is very weak. 

Ktownphoneco

The first thing I would try is another "U1" receiver cartridge.     It's not uncommon for conventional receivers in any telephone handset to get weaker over time.   If the drum type magnet inside the "U1" gets weak, receiver volume will drop.    I've replaced a number of "U1" receiver cartridges over the years.

Jeff Lamb   

poplar1

Does your 2554 have a 35-type dial or a 72-type (# stamped on front of dial)?

Try temporarily moving the green receiver wire from S (where white-blue dial wire is) to GN (where white dial wire is). This will bypass the muting contacts on the dial.

The other muting contacts are the red and black hookswitch wires. You can temporarily remove the red wire from S or the black wire from R.

BSP 502-523-402, i7, May 1978 in SWBell Station Service Manual, Sept. 1979.
"C'est pas une restauration, c'est une rénovation."--François Martin.

Rotorman

I tried several other known good handsets and the dial tone is still barely audible.  I picked up several other 2554 phones and looked inside to find huge variations in parts locations, wires, wire colors, components, etc.....i suspect it will take some time digging up the wiring info on these sets that I mistakenly assumed would be pretty much identical.   

poplar1

Did you try moving the receiver wire from S to GN (see above)?
"C'est pas une restauration, c'est une rénovation."--François Martin.


Key2871

Well I know I have had several sets where you could hear the touch tones fine, but not the dial tone.
Try what poplar said to try, that will tell you for sure.
KEN

poplar1

If you have an older 2554 with a 4010D network, then that network does not have S  and T terminals. Instead, there is a terminal strip with 1, 2, 3, 10, 11. The green,  red, and yellow wires from the line plug connect to terminals 1,2, and 3. Terminals 10 and 11 are equivalent to S and T. So, you would move
the green receiver wire from 10 to GN rather then S to GN if you have the older network.
"C'est pas une restauration, c'est une rénovation."--François Martin.