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Need help identifying an electronic part.

Started by davidbholcomb, April 17, 2014, 03:46:10 PM

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davidbholcomb

I just picked up this 302 with all matching numbers from Nov. '48 and I was wondering what this small electronic part was and what purpose it might have served. Do I need to keep it on the phone. Thanks.
Dave, who still needs a Transmitter Bracket for the Automatic Electric Type 38 Handset.

poplar1

It's probably a varistor since it is in parallel with the receiver (white and red handset wires). It reduces the voltage spikes as when hanging up, going off hook, or when the dial returns. Unlike the $100 extra charged by opw and phoneco for replacing original parts with a modern network, this is actually a low-cost improvement.
"C'est pas une restauration, c'est une rénovation."--François Martin.

Phonesrfun

-Bill G

Kenton K

I would keep in in the phone if it improves the sound quality when dialing/hanging up/picking up. The 5H dial leads are easily bent, which results in the pops.  They can be bent back, but this is another solution to fix the pops.

KK

twocvbloke

GPO 700 series phones employ something similar, a Rectifier No. 205, which is just two diodes wired back-to back in parallel, it reduces the pops (which they called Acoustic Shock) from the hookswitch when you need to press it when using the phone, I tried it with and without on my recent black 706 and it is noticeable having the component in place versus not, so this varistor I'd leave in place as it's a beneficial piece, even if not 100% original to the phone... :)

davidbholcomb

Thanks all for the info and help. Very interesting.
Dave, who still needs a Transmitter Bracket for the Automatic Electric Type 38 Handset.

poplar1

Just to clarify, on most Western Electric phones (20ALs, 51ALs, 202s, 302s, 500s, etc.) there should not be a loud click when hanging up because the receiver opens before the phone is disconnected.

If you are used to a 500 or later phone which has a varistor on the back of the receiver, then on a 302 the voltage spikes are noticeable for example with certain types of call waiting and when first getting dial tone. And they are even more noticeable if, as Ben pointed out, the dial contacts or hookswitch contacts are not adjusted properly.
"C'est pas une restauration, c'est une rénovation."--François Martin.