Bell System 2752 panel phone problems

[dialanumber]

Anyone have any experience with a Bell Systems 2752 wall panel phone, 1752 or 752? I am working on a 2752 phone that has a bad speaker for speakerphone that has a open circuit. Anyone recall what ohm speaker was used for these speakerphones. Since the bad speaker isn't reading any resistance I can't tell what to replace the speaker with. It's next to impossible to find another 2752 to scavenge from or to check ohms of speaker. I have looked in every old manual that I can get my hands on and can't find specs for the speaker. Any help is greatly appreciated!

 

[jrgood0852]

Peruse this site, dial. May find answer here. Otherwise I bet you can find one on Ebay....................

http://www.telephonecollectors.info...s/2276-component-specifications-wirecolors-tl

 

[jrgood0852]

Check this out, too...............

http://www.beatriceco.com/bti/porticus/bell/bsp.html

 

[SYQUEST]

Which Speakerphone set are you using with the 2752, the 3A or 4A type? The 4A uses a KS-20958 speaker 45Ω voice coil, which is in the 108 loudspeaker set. The 3A used the 760A loudspeaker which has a KS-16881-L2 or L4 speaker in it. I don't have the reference document available at this time, but the impedance is most likely 45Ω also. Quam-Nichols made both speakers OEM for Western Electric at the time. Those kinds of specifications were sporadically published in the BSPs, but were usually in the SD or CD for that product. They were also in the Western Electric Repair Spec., but it seems very few of those ever saw the light of public day! Except for the copies I have in my possession. I worked at WECO in the 1970s.

Hope this helps!
....JIM....

 

[dialanumber]

Thanks Jim,

The Speakerphone is internal to the phone that mounts to the chassis of the phone. Here is a link to Practices for phone:

http://bellsystempractices.org/500-/512-/512-620-480-i03_1974-04-01.pdf

I can't find ohm's of speaker anywhere. The part number that was on the speaker itself is KS-19687L1 and it had another number stamped on it 3747704. Your note about Quam makes since to me because I found a new Quam 8 ohm speaker that fit the mounting post and plastic cover perfectly. Any thoughts on ohm's? Still think 45 ohm?

Thanks

 

[SYQUEST]

Hi dialanumber,

The KS-1987L1 speaker is part of the 762A loudspeaker unit. Some 762A units had speakers with the part number P21F246 as pictured in the BSPs 512-620-480 and 512-620-200. I believe all the speakers used with the type 3A/B Speakerphone System control unit 55A/B have 45Ω voice coils, or pretty close to it. The speaker circuit in the control unit is transformer coupled. You might check with Quam-Nichols directly and see if they have one in that size and impedance. Newark Electronics in Chicago does sell Quam-Nichols. Some of the models Quam produces may be out-of-stock, until they get enough orders to do a production run to fill the orders. That link to the BSP was helpful, but a terrible scan copy.

By the way, the difference between the 55A and 55B control units is, the B version works with Touch-Tone™ sets or rotary dials. The A version is rotary dial only.

....JIM....