701B Princess voltage issue?

[Alex G. Bell]

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.

By "Disconnect both output leads of the lamp power source from the wiring" I meant you should disconnect the transformer ("wall wort") leads from the terminals to which they were connected, leaving the Princess cord still connected to those terminals.  (In all future statements I will simply use the term "transformer" to refer to the AC power adapter you refer to as a "wall wort".)

By "and measure the AC voltage from either lead of its output leads to the lamp voltage input terminals from which they were disconnected" I meant measure the AC voltage from either lead of the transformer (with the other transformer lead not connected to anything) to the each of the terminals they were connected to before you disconnected them, to which the Princess phone cord leads are still connected.

By "to make the measurement with the Princess phone connected to the line and on hook (the condition where noise is experienced)" I meant that you should make the above AC voltage measurements with the Princess phone in the condition which normally produces the noise.

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

If you are measuring this "1.51amps" current by connecting the 2 test leads of the meter directly to the 2 transformer leads with the meter set to AC or DC AMPS or mA or "Current" you are applying a short circuit to the transformer which will burn it out or blow its internal fuse if left connected that way even for a few seconds.  Doing this with a larger power supply could burn out the meter instead. 

If you did not arrive at the conclusion that the the 5.25VDC is @ 1.51 amps by connecting the transformer and meter as I described above please explain how the meter was connected and it switches set to arrive at this reading or post a sketch.

The lamp circuit could not possibly draw 1.51A.  The bulb is rated 250mA, 1/6th that amount.  1.51A is an erroneous result which has no bearing on the actual noise problem but you need to understand how to make proper current measurements.

Current readings are always made by connecting the ammeter (DMM or VOM set to an AMPS or mA range) in series between the power "source" (transformer) and the "load" (the lamp in the phone), never by connecting the meter directly across the source since doing this pits a theoretically "irresistible force"  (the source or transformer) against an immovable object (the meter).  One or the other will be destroyed in most cases unless there is some protection mechanism, which you cannot assume to be present. 

Only voltage readings are made by connecting the meter (set to VAC or VDC) directly across the output of the source.  When a current reading is made with the meter in series with the load as described above the load limits the current to a safe value and the meter properly measures the load current rather than the amount of current the source is capable of delivering, which is what it measures when the meter is connected directly across the source with the meter set for measuring current.   If this is not clear I will create a sketch or find one on line.

[Dominic_ContempraPhones]

The standard power there is what, 6-8 volts DC at about 290 mA.

Make sure your connection to the xlink is a 2 pin RJ11 and not 4 pin.
Inject power into the phone directly to the appropriate terminals if you're using the old transformers.
There is a shielded type of RJ11 cord you can also use.  It's looks like Ethernet and is straight, not an x-over.

Cut off one end and crimp spade lugs on.

Try the phone without x-link on a friend's phone line.  X-Link was junk as I recall.  I actually threw it in the garbage.

Make sure none of the spade lugs kiss.

[AL_as_needed]

Thank you for clarifying, just wanted to be double sure I am testing things correctly so as to get to the bottom of this. Especially considering I am acting as your hands in a way to provide the needed data.

So.... with the transformer leads disconnected from their respective terminals in the ringer (with the phone on the hook) ACv read 0 for testing between both leads and their terminals.

The 1.51 amps was taken by setting my meter to the 10A DC setting and having the test leads in the appropriate sockets. Testing is limited to momentary contact as yes, the meter is internally protected (fused). Is the number 100% accurate, likely no given the short contact time and the time it takes the meter to settle on a value. Just figured I'd take the measurement as yet another data point to consider or disregard in the overall trouble shooting.

The standard power there is what, 6-8 volts DC at about 290 mA.  He's getting EMF through the air Alexander Einstein Bell.

Make sure your connection to the xlink is a 2 pin RJ11 and not 4 pin.
Inject power into the phone directly to the appropriate terminals if you're using the old transformers.
There is a shielded type of RJ11 cord you can also use.  It's looks like Ethernet and is straight, not an x-over.

Cut off one end and crimp spade lugs on.

Try the phone without x-link on a friend's phone line.  X-Link was junk as I recall.  I actually threw it in the garbage.

Make sure none of the spade lugs kiss.

Thanks for the imput, however the xlink is not the root cause of the issue, regardless of any quality issues that may or may not exist within the xlink itself.

It (xlink) has handled any and all combinations of any three rotary/touch tone phones from my collection at a time with no issue (three phones with mech. ringers is about the max REN the xlink can take). The main problem, the "hum" or buzz only arises when the 701B Princess is thrown into the mix. I have a WE 565HK and WE spokesman (hard wired to that particular phone) that is also illuminated/powered with a similar transformer, and there is no hum/buzz/voltage put back into the line.

[Dominic_ContempraPhones]

Thank you for clarifying, just wanted to be double sure I am testing things correctly so as to get to the bottom of this. Especially considering I am acting as your hands in a way to provide the needed data.

So.... with the transformer leads disconnected from their respective terminals in the ringer (with the phone on the hook) ACv read 0 for testing between both leads and their terminals.

The 1.51 amps was taken by setting my meter to the 10A DC setting and having the test leads in the appropriate sockets. Testing is limited to momentary contact as yes, the meter is internally protected (fused). Is the number 100% accurate, likely no given the short contact time and the time it takes the meter to settle on a value. Just figured I'd take the measurement as yet another data point to consider or disregard in the overall trouble shooting.

Thanks for the imput, however the xlink is not the root cause of the issue, regardless of any quality issues that may or may not exist within the xlink itself.

It (xlink) has handled any and all combinations of any three rotary/touch tone phones from my collection at a time with no issue (three phones with mech. ringers is about the max REN the xlink can take). The main problem, the "hum" or buzz only arises when the 701B Princess is thrown into the mix. I have a WE 565HK and WE spokesman (hard wired to that particular phone) that is also illuminated/powered with a similar transformer, and there is no hum/buzz/voltage put back into the line.

- You have a 701B.  701Bs have no internal ringer.
- Are you using an external E1A ringer with it?  Y / N
- Do you have a terminal strip numbered 1 thru 7?
- How many conductors does the cord have, and what are their colors

The yellow going to the transformer must also be grounded.  I found this 701B Northern schematic eons ago.
It depicts bridged ringing without the E1A.  Tell me what you've got, and we'll take it one step at a time.  I don't bite so don't worry.  It could be wired for tip party, ring party, tip party with 2560 ident. ground.

[Alex G. Bell]

Thank you for clarifying, just wanted to be double sure I am testing things correctly so as to get to the bottom of this. Especially considering I am acting as your hands in a way to provide the needed data.

So.... with the transformer leads disconnected from their respective terminals in the ringer (with the phone on the hook) ACv read 0 for testing between both leads and their terminals.

The 1.51 amps was taken by setting my meter to the 10A DC setting and having the test leads in the appropriate sockets. Testing is limited to momentary contact as yes, the meter is internally protected (fused). Is the number 100% accurate, likely no given the short contact time and the time it takes the meter to settle on a value. Just figured I'd take the measurement as yet another data point to consider or disregard in the overall trouble shooting.

You're welcome.  Just to verify, can I assume that the voltage reading which returned a 0 result was done on the lowest AC voltage range, probably 200mVAC?  If so I need to think about another way to get at the problem.

Where is the SL switchhook ("line switch" on BSP 502-710-400) lead connected?  What else is on that terminal?

Where is the SL-YL switchhook lead connected?  What else is on that terminal?

Even if the 1.51A reading does not damage the meter or transformer it simply has no meaning since, if I understand correctly what you are doing, I think you are measuring the short circuit current and the transformer is never used that way.  It is probably not capable of delivering 5.25V @ 1.51A. because when it is delivering 1.51A it is short circuited and the voltage cannot be 5.25V at that moment. 

A valid reading would require connecting the transformer to a load to which it could be connected constantly and first measuring the current in series with the load and then the voltage across (in parallel with) the load.

Are there output voltage and current ratings actually marked on the transformer? 

[AL_as_needed]

Well gentlemen, first and foremost thank you for your assistance!

However after all of the above troubleshooting, a personal character flaw once again revealed itself. While I can appreciate the methodical, scientific approach to a problem, part of me also indulges in the "lets just wing-it" strategy.   

Long story short, after randomly disconnecting one wire at a time while listening to the hum (on a separate phone) for any changes, it was found that the white wire in the line cord (running from terminal 3 in the ringer to a ground (?) in the phone) was the issue. Disconnecting the wire in the ringer eliminated the hum entirely and the phone still retains all aspects of its function without issue.

Scientific? Nope.... Technically correct solution? Probably not... But it worked and I'm not one to argue with results. 

[poplar1]

The yellow going to the transformer must also be grounded.  I found this 701B Northern schematic eons ago.

Note 2:  Ground may be omitted if not required for service; not needed for protection of dial light transformer.
Fig. 1, ISS 6, BSP Section 502-710-400


[The yellow conductor of the inside wire did not need to be connected to ground at the protector for individual lines.]

[poplar1]

Long story short, after randomly disconnecting one wire at a time while listening to the hum (on a separate phone) for any changes, it was found that the white wire in the line cord (running from terminal 3 in the ringer to a ground (?) in the phone) was the issue. Disconnecting the wire in the ringer eliminated the hum entirely and the phone still retains all aspects of its function without issue.

The white wire, from terminal D in the phone, was usually connected to the same screw terminal as the red wire from the phone (on the wall connecting block or 4-prong plug).

Indeed, the white wire is only "hot" when the phone is on-hook, which is when you heard the hum. Was anything else other than the white wire connected to 3 inside the E1A ringer?

The blue wire from the phone was connected to the same terminals as the black conductor both inside the phone (4) and at the connecting block or external ringer (4).

[AL_as_needed]

Indeed, the white wire is only "hot" when the phone is on-hook, which is when you heard the hum. Was anything else other than the white wire connected to 3 inside the E1A ringer?

The blue wire from the phone was connected to the same terminals as the black conductor both inside the phone (4) and at the connecting block or external ringer (4).

No, the white was on its own inside the ringer block. There is a thread somewhere on here where I was provided some BSPs and other helpful diagrams from the TCI library when I initially wired it up some time ago.

The princess has an odd wiring scheme with that double positive, maybe they figured on add-ons and further development? Either way, by eliminating and isolating the white all together the phone is now acting as it should.

[Dominic_ContempraPhones]

Well gentlemen, first and foremost thank you for your assistance!

However after all of the above troubleshooting, a personal character flaw once again revealed itself. While I can appreciate the methodical, scientific approach to a problem, part of me also indulges in the "lets just wing-it" strategy.   

Long story short, after randomly disconnecting one wire at a time while listening to the hum (on a separate phone) for any changes, it was found that the white wire in the line cord (running from terminal 3 in the ringer to a ground (?) in the phone) was the issue. Disconnecting the wire in the ringer eliminated the hum entirely and the phone still retains all aspects of its function without issue.

Scientific? Nope.... Technically correct solution? Probably not... But it worked and I'm not one to argue with results.

It isn't.  5 to 7 to 1 to 6 should be there and blue goes to K from 4.  White and Blue support Tip Party Ringing with Ground Identification -- in that config., they connect with yellow, which is grounded.  Northern used a different cord depending on the scenario.

In bridged without an E1A, white and ring (L2) kiss on both ends to whatever comes from C.

In 1A2 with A lead control, that white wire went to a totally different contact in the hookswitch with extra gizmos.

Northern did a full write up on it that might not appear in the WE documentation.

[ThePillenwerfer]

I'm late reading this and freely admit I know nothing about this particular telephone or American systems in general.  However, my bet would be that the wall wart is a switch mode one and these are notorious for introducing noise into circuits.  I found that the one that came with my ATA was inducing hum into my conventional landline.  This went away as soon as I made a linear replacement, ie one with a traditional transformer.

It's easy to tell what type you are dealing with as switch mode supplies are very light in comparison to old linear ones.  A linear one capable of delivering 1.5A would be like a brick.

By the way, I'm a fellow exponent of "Let's just wing it."  Glad to hear you got it sorted.

[Alex G. Bell]

I'm late reading this and freely admit I know nothing about this particular telephone or American systems in general.  However, my bet would be that the wall wart is a switch mode one and these are notorious for introducing noise into circuits.  I found that the one that came with my ATA was inducing hum into my conventional landline.  This went away as soon as I made a linear replacement, ie one with a traditional transformer.

It's easy to tell what type you are dealing with as switch mode supplies are very light in comparison to old linear ones.  A linear one capable of delivering 1.5A would be like a brick.

By the way, I'm a fellow exponent of "Let's just wing it."  Glad to hear you got it sorted.

It's a reasonable supposition and switched mode power converters (especially small wall mounted ones) often do cause noise problems but in this case one side of its output was connected to the speech circuit through a cradle switch contact which was closed when the handset was on-hook.  That's why the problem was only audible on other phones but not on the one which was causing the problem.  Isolating the lamp circuit from the speech circuit got rid of the noise.

[poplar1]

It's a reasonable supposition and switched mode power converters (especially small wall mounted ones) often do cause noise problems but in this case one side of its output was connectedj to the speech circuit through a cradle switch contact which was closed when the handset was on-hook.  That's why the problem was only audible on other phones but not on the one which was causing the problem.  Isolating the lamp circuit from the speech circuit got rid of the noise.

It is true that when the phone is on-hook, the ring side of the line is connected through the line switch slate lead to D, through the white conductor of the mounting cord, to terminal 3 of the E1-type ringer.

However, 3 is a blind terminal, and as he stated, nothing is connected to 3 other than the white conductor. So, how does connecting the white wire to terminal 3 in the E1 cause a hum, and how does removing it eliminate the noise, if terminal 3 is indeed a blind terminal, i. e., electrically isolated?

[Alex G. Bell]

It is true that when the phone is on-hook, the ring side of the line is connected through the line switch slate lead to D, through the white conductor of the mounting cord, to terminal 3 of the E1-type ringer.

However, 3 is a blind terminal, and as he stated, nothing is connected to 3 other than the white conductor. So, how does connecting the white wire to terminal 3 in the E1 cause a hum, and how does removing it eliminate the noise, if terminal 3 is indeed a blind terminal, i. e., electrically isolated?

I don't know.  Once he decided to "wing it" I stopped trying to figure out how by following the discussion on a wiring diagram or schematic.  Perhaps there are connections he is not aware of.  The fact is that opening that path removed the problem, so the empirical evidence is that somehow there is a path through the SH contact. 

I've gone down the road before of trying to help someone troubleshoot over the internet and reached the end only to discover that the problem was something which would have been obvious visually if I had been looking at the actual item but never came to mind as a possibility to mention as something to check.

If we/I had known earlier that the problem only occurred with the Princess on hook I would have gone directly to that SH contact without attempting to detect leakage with meter measurements.  But as the saying goes, "hindsight is 20/20".

[poplar1]

No, the white was on its own inside the ringer block. There is a thread somewhere on here where I was provided some BSPs and other helpful diagrams from the TCI library when I initially wired it up some time ago.

The princess has an odd wiring scheme with that double positive, maybe they figured on add-ons and further development? Either way, by eliminating and isolating the white all together the phone is now acting as it should.

Where is the white line cord wire connected inside the phone -- to terminal D? Is the slate [solid gray] wire from the line switch also on D? If yes to both, then I don't see any cross between the lamp circuit and the talk path

One possible source of confusion is the inconsistency of the mounting cord colors used for the lamp circuit:

701B.    Black and yellow of D6x cord
702B.    Black and white of D5AK cord
702BM (modular) Black and yellow of 623P4 jack