701B Princess voltage issue?

[Alex G. Bell]

So the plot thickens....

The hum is only present when the wall wort AND the phone is connected to the line (plugged in). I did consider that maybe the xlink and the princess light wall wort were on the same electrical circuit and that one or the other was putting out "noise" into the circuit causing the other to have irregular voltage, but not the case. I tried other outlets and wall jacks and the hum was the same.

But...

Turns out after some poking around with my multi meter and finding nothing in the way of stray voltage....the hum is only there when the princess 1) has its light circuit plugged in 2) the handset is hung up/light is off.   

Lastly, not sure if i mentioned this earlier; the hum can only be heard on another set, and not on the princess. For example if the princess is on the hook (hung up)   and I pick up the handset on my 554, 302, etc (or any other in my collection as I swapped them around just to test) I hear it.

Good info!  It stands to reason that if the hum is only present on the other phones when the Princess handset is hung up that you also would not hear it on the Princess.  However I'm curious about (2).

The Princess has a switch setting to have the lamp on dimly when on hook or to turn it off.  Are you saying that if you set the switch so the light is on dim with the handset hung up that there is no hum?

[Victor Laszlo]

Unless I missed it, has anyone asked if the telephone, and dial lamp transformer, are arranged with modular cords and plugs? If so, a modular adapter would probably be in the circuit somewhere, and those modular adapters, in the style of the WE 267-series, often develop high resistant crosses between the contact fingers, due to moisture and dust.

[Alex G. Bell]

Unless I missed it, has anyone asked if the telephone, and dial lamp transformer, are arranged with modular cords and plugs? If so, a modular adapter would probably be in the circuit somewhere, and those modular adapters, in the style of the WE 267-series, often develop high resistant crosses between the contact fingers, due to moisture and dust.

Good question for general info but if that were the cause I don't see how the hum would be affected by whether the handset was hung up or not. 

The handset having to be hung up suggests something like the lead for the contact on the cradle switch that closes when the handset is hung up is perhaps terminated onto a lamp circuit terminal so it ties one side of the lamp circuit into the line and the lamp transformer (connected only to one side of the line) slightly unbalances the line.

[Victor Laszlo]

I will suggest this next step in trouble-shooting:  (it should have been the first, but I'm late to the party)

Open both sides of the telephone line at the demarc.

With all phones and the dial lamp transformer plugged in, using a meter, test for A.C. and for ground on the subscriber T & R (tip and ring) wires, going from ground to each individually, and then across the pair.  Across the pair means from Tip to Ring. Do this with the Princess on-hook, and then off-hook.

Please report your measurements.

1. Ground to Tip (on-hook)

2. Ground to Ring (on-hook)

3. Across the pair (on-hook)

4. Ground to Tip (off-hook)

5. Ground to Ring (off-hook)

6. Across the pair (off-hook)



Please stop using the term "wort" to mean "wart" to mean "dial lamp transformer."

[Alex G. Bell]

I will suggest this next step in trouble-shooting:  (it should have been the first, but I'm late to the party)

There is no demarc.  Dial tone is coming from an X-Link blue tooth cellphone-to-T&R adapter.

It's not clear to me whether you're suggesting testing the IW (inside wiring) or the incoming pair from the CO (which does not exist as such).

[Victor Laszlo]

"...test for A.C. (alternating current) and for ground on the subscriber T & R (tip and ring) wires..."

"Opening the demarc" is generic advice in initiating any POTS (plain old telephone service) trouble shooting. The fact that the victim is using a source of dial tone from a little box on his desk does not alter my advice.

I see no reason to test the incoming (dial tone source) wires, looking back toward the CO (central office) or any other local source of DT (dial tone.) I would think that it was obvious that I was referring to a possible source of foreign potential on the victim's inside wiring scheme, looking towards, electrically, his subscriber equipment.

Many times, perhaps not significant in this instant case, I have found that vestigial wiring, especially that going back towards a demarcation that has been RIP (retired in place) can be the cause of trouble. If the person (subscriber or employee) decided to back-feed the dial tone into the subscriber wiring, from any point other than the NID (network demarcation device) and DID NOT go the the ILEC (incumbent local exchange carrier's) demarc to turn back the original incoming wires, foreign potential can be introduced from the still-connected OSP (outside plant.)

[AL_as_needed]

Good info!  It stands to reason that if the hum is only present on the other phones when the Princess handset is hung up that you also would not hear it on the Princess.  However I'm curious about (2).

The Princess has a switch setting to have the lamp on dimly when on hook or to turn it off.  Are you saying that if you set the switch so the light is on dim with the handset hung up that there is no hum?

The hum is present when the lamp is either dim,or off completely. When the handset is off hook and the lamp is at "full" brightness, the hum is gone. Strange stuff for sure.

Unless I missed it, has anyone asked if the telephone, and dial lamp transformer, are arranged with modular cords and plugs? If so, a modular adapter would probably be in the circuit somewhere, and those modular adapters, in the style of the WE 267-series, often develop high resistant crosses between the contact fingers, due to moisture and dust.

This phone is using its original non modular cord, with spade connections running into the ringer. From the ringer there are separate lines for the modular jack and a wall wort (also with spade connections). I went back and applied heat shrink tubing to the wall wort (where it ties into the lamp circuit posts in the ringer) and the hum is still there.

Also to clarify, the wall wort has an output of DC 6v (actually 5. something) @ 1.5 amps.  The Xlink has a similar DC output @ about 5.7-5.5 volts and an AC output @ 10-11 volts at dial tone (not at ring cycle) according to my meter.

The hum is not noticeable when the xlink is supplying dial tone, only when it is at "idle". I currently have it set so that it removes all line voltage when no longer connected via blue tooth. So the xlink is on and has power to itself, its just transmitting any down the phone line.

[Victor Laszlo]

All very interesting, but please go back and read my trouble-shooting advice in reply #18.

Then please fill in the answers to the 6 questions.

Then we can begin to find the problem.  Anything else is conjecture and head-scratching.

Telephone problems of this type are 99% of the time caused by some metallic fault. Use your meter. Record the findings. Tell me what they are. I will help you fix the problem.

[AL_as_needed]

Ok, so here goes the findings, all in ACv. This is with the phone in a sort of default mode, on the line,wall wort plugged in and the lamp switch set to lo/hi (traditional night light setting).

On Hook:

1) G-T= 0v

2)G-R= 0v

3)ATP= 102.7-102.5v (!?)

Off Hook:

4) G-T=0v

5)G-R=0v

6)ATP=6.1-6.2v

I tried these same tests with the lamp switch set to the off/hi position, and there were no change in the results.

[AL_as_needed]

Also to further cut down variables, I did the above mentioned six with the wall wort disconnected completely. I allowed it a solid minute to discharge (just to be sure) and results were still unchanged.

[Victor Laszlo]

Interesting.

1. Can you now measure the output of the transformer, where it attaches to your wiring?

2. Could you also disconnect the transformer completely and measure across the T & R of your wiring in both off- and on-hook conditions?

[Alex G. Bell]

Ok, so here goes the findings, all in ACv. This is with the phone in a sort of default mode, on the line,wall wort plugged in and the lamp switch set to lo/hi (traditional night light setting).

On Hook:
1) G-T= 0v
2) G-R= 0v
3) ATP= 102.7-102.5v (!?)

Off Hook:
4) G-T=0v
5) G-R=0v
6) ATP=6.1-6.2v

I tried these same tests with the lamp switch set to the off/hi position, and there were no change in the results.

First I'd like to explain that you (of course) do not actually have ~102.7VAC or ~6.1VAC across T&R ever.  You have a meter which reads the DC voltage present when set to read AC if DC is also present.  Some better meters ignore a DC voltage appearing in series with ("superimposed on") AC when set to read AC. 

Other inexpensive ones require adding an external capacitor in series with the meter for it to ignore irrelevant superimposed DC.  For a ringing voltage test with your meter this would be necessary because you would want to read only the AC voltage.  The high reading (102V) which surely exceeds the actual DC voltage too probably comes from how the meter performs and displays AC voltage readings and is much higher than the actual DC voltage too.  You can repeat the T-R voltage measurement with the meter set to DC volts to see what the actual DC voltage is.   Probably 48VDC.

What Victor suggested: measuring AC voltages to ground would be valid if you were not using an X-Link device.  I would suggest another measurement instead:  Disconnect both output leads of the lamp power source from the wiring and measure the AC voltage from either lead of its output leads to the lamp voltage input terminals from which they were disconnected to make the measurement with the Princess phone connected to the line and on hook (the condition where noise is experienced).

[Dominic_ContempraPhones]

An x-link is a cellular gateway, and even when it has a wireline jack -- the thing is crud.  I was asked to evaluate it.  It couldn't even handle a modern phone properly.  Use a Signature Princess Transformer with the adaptor, and your issues will be gone.  And ditch the x-link for Pete's sake and make sure your connection is 6P2C RJ connector.

[AL_as_needed]

Interesting.

1. Can you now measure the output of the transformer, where it attaches to your wiring?

2. Could you also disconnect the transformer completely and measure across the T & R of your wiring in both off- and on-hook conditions?

1) The output for the wall wort, as measured where it ties into the ringer is 5.25v DC @ 1.51 amps

2) I did try this as part of the initial six tests you'd suggested, results were the same as those listed.

Also to further cut down variables, I did the above mentioned six with the wall wort disconnected completely. I allowed it a solid minute to discharge (just to be sure) and results were still unchanged.

[AL_as_needed]

I would suggest another measurement instead:  Disconnect both output leads of the lamp power source from the wiring and measure the AC voltage from either lead of its output leads to the lamp voltage input terminals from which they were disconnected to make the measurement with the Princess phone connected to the line and on hook (the condition where noise is experienced).

Could you please reword this? Which leads would I disconnect, those coming off the wall wort directly or the leads for the lamp circuit within the line cord? Thanks.