News:

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

Main Menu

Need help restoring and wiring a WECo 151-AL / 634A Subset

Started by cloyd, June 16, 2016, 04:41:22 PM

Previous topic - Next topic

unbeldi

That is correct, the Z on the receiver indicates its 'polarity', that side should be indirectly connected to the ring side, i.e. the negative side of the line, which manifests itself as the green receiver wire.
However, these sets do use a capacitor to block direct current through the receiver, so if properly wired, not much harm is possible.  Tina also reported that the magnetic pull on the diaphragm was strong.

cloyd

Quote from: unbeldi on June 30, 2016, 07:52:02 PM
Well, I don't know how bad it is for you.

'Volume' is relative, for example:  I use a milliwatt tone generator to compare receivers. The generator produces a constant tone of 1000 Hz at a constant power of 1 mW, that's why it is called a milliwatt (mW) tone.   Comparing a 144 receiver on a No. 51 candlestick, with a 302 telephone side by side, I find that the 144 is actually louder.

Now, the candlestick is a sidetone instrument, and the 302 is an anti-sidetone set, so the comparison is not quite fair.  An anti-sidetone circuit, despite being more modern in historical perspective, is actually slightly less efficient than a sidetone circuit.

Isn't the 151-AL an anti-sidetone phone?
I have a 302 and it is significantly louder and easier to hear.

Is there a way that I can quantify the receiver volume?
What else could cause the receiver to have low volume in the receiver?

Tina
-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- 1885

unbeldi

Quote from: cloyd on July 03, 2016, 01:55:52 PM
Isn't the 151-AL an anti-sidetone phone?
I have a 302 and it is significantly louder and easier to hear.

Is there a way that I can quantify the receiver volume?
What else could cause the receiver to have low volume in the receiver?

Tina

Yes, the 151AL and a 302 should have the same performance essentially if they both use the same transmitter and receiver elements.
For testing the receiver, you could use the handset of a 302 and wire it in place of the 144 receiver of your desk stand.  The receiver wires of the handset are the white and red wires, so if you disconnect the 144 cord from its terminals in the base and replace it with those handset wires you can test your desk stand with a known good HA1 receiver element.

For quantifying volume you really need a known audio source and measure the loudness of each receiver with a sensitive microphone and recording equipment.
As I said, I use a milliwatt source.  There still are telephone numbers at central offices you can call to get the signal on the PSTN.


cloyd

I tried substituting the 302 F1 receiver for the 151-AL No.144 receiver.  The volume was definitely greater with the 302.  I tried using a sound meter app with my phone and the 302 tested at 33 dB and the 144 was 26 dB.  So, it isn't my imagination which is reassuring to me.

Do I need a different magnetic element for my old receiver?  I can't think what else it could be.

Thank you,

Tina
-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- 1885

unbeldi

Quote from: cloyd on July 04, 2016, 04:41:02 PM
I tried substituting the 302 F1 receiver for the 151-AL No.144 receiver.  The volume was definitely greater with the 302.  I tried using a sound meter app with my phone and the 302 tested at 33 dB and the 144 was 26 dB.  So, it isn't my imagination which is reassuring to me.

Do I need a different magnetic element for my old receiver?  I can't think what else it could be.

Thank you,

Tina

Ah, the sound-app idea is great!
Seems indeed to be a weaker receiver then.  I don't know what can be done successfully to improve the volume. The magnetic properties of the core may have suffered over time.
Perhaps someone hot-wired the set for a long time.
I think we have to realize that these instruments are extremely beyond their designed and expected lifespan.  If I do get to be that old, I'll know to be happy to make any sounds.


cloyd

Thanks for the compliments unbeldi!

I agree about the age of the phone.  It would be nice to be able to use it.  If there isn't any background noise, the volume is OK.  My daughter is excited about using it in her bedroom so, between young ears and a closed door, she may do just fine with it!

I thank everyone for your generous and patient help with this project!

Tina Loyd
-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- 1885

Doug Rose

Tina....One last try on your volume issue...with a flat head screwdriver scrape the two bars on the end of the receiver and get them to shine. Same with the disk that snaps on to it. It will give you a much better connection. It has helped me in the past....good luck..Doug
Kidphone