This WAS the message "Phone makes terrible sound w/ ans machine"
I am now checking the phone line, but dont have one of those little
LED testers. The green and red wires are connected to the correct
screws on both ends, but there could be a splice in the crawl space
under the house, and I am not crawling under there in this cold
I have a digital, and an analog Multimeter. How can I test to be sure
the polarity is correct using either of these meters?
Except I only got solid wires. One red, one green. I did find that
with the meter set to DC, if the red wire from the meter is put on the
red phone wire, I get a negative voltage reading of about 52 volts.
Reverse the meter leads and I get a positive reading. This is the
same on all phone jacks, and on the main phone company box outside.
That tells me that all phone jacks are the same polarity, but I wonder
if the phone company wires are not reversed. Both are black, so how
do I know? This is possible too, because I had a porch built, and
that phone jack was moved. The wires were disconnected because they
were too long after the move. So, I do not doubt they could be
reversed. After all, both are the same color.
Is there a standard where the red should be POS. or NEG ???
Which is which, and how does that compare with ring and tip (I never
Green= tip, Red= ring.
Yellow= tip, Black= ring.
Remember the tip is the positive (ground) terminal and the ring is
negative. Historically phones were all negative with respect to ground.
Black (neg) meter lead to the tip and red (pos) meter lead to the tip
should indicate a negative voltage.
You mean the Black (neg) meter lead to the tip and red (pos) meter
lead to the RING, right? (you said TIP for both).
If that's the case, that is what I have.
Red meter lead on red wire = negative voltage.
By the way, I have now checked polarity on every wire, and from what
you just said, it appears the polarity is correct. I eliminated the
modem entirely, changed all the phone wires, and swapped answering
machines. After all of this, I still had the problem.
However, when changing phones, the problem is gone.
The guilty phone is almost brand new. I bought it a few months ago.
It's a Lenoxx PH-319. The phone itself is great, sounds good, looks
good, even has a headset, and it was cheap to boot. But the cheap may
be the problem. When I plug in an ancient "princess phone", the
problem is gone. I just emailed the Lenoxx company. Lets see what
Sorry about my error. Your interpretation is correct.
I looked at the on-line manual for this phone and may have found the
problem on the last page where it reads "Made in China."
I found that over time we had added about a dozen phones. This past
year we've had varying problems with most of them. I threw out the
phones from China (8 of them) and replaced them with good quality phones
and am much happier with the performance. The ones that I like best are
made by Plantronics. Sony comes in a very close second. From a
life-cycle cost perspective I've come to believe that Chinese products
aren't worth the "savings."
Most modern phones have polarity protection and can care less about
The only phones that won't work are $2 drug store phones and old
Western Electric built-like-a-truck sets. Come to think of it, even
some of the $2 phones have polarity protection. <G>
The Red ("ring") should be negative with respect to the Green ("tip") wire,
Also Yellow is "ring" therefore negative and Black is "tip" therefore
positive if there is also a second line on the "POTS" (Plain Old Telephone
Service) cable. Alternately the Yellow and Black were used for 24V (28V?) AC
power from a small transformer in the house to light phones w/ lighted
dials, e.g. the Princess phones. Really old cable may lack the Black wire.
Ring and Tip refer to the side contact and the end contact of a phone plug,
as used on old switchboards, and quite similar to 1/4" stereo headphone
plugs used on Stereo receivers, tape decks etc. 48V DC nominal is present
if the phone is on hook, off hook is will be more like 6-10V, and if it
rings, 20Hz AC ring voltage of about 90V(?) will also be applied.
For modern Cat 3 or Cat 5 twisted pair phone wiring (same stuff used for
networking) the colors become: Ring - Blue w/ White, Tip - White w/ blue for
the first pair, then the same but Orange/White & White/Orange, Green/White &
White/Green, Brown/White & White/Brown. POTS is obsolete and shouldn't be
used for new wiring.
Actually the phone system uses a -48V supply. Tip is neutral/ground (green)
and ring (red) is at -48V DC. But it really doesn't matter if red and green
or black and yellow, if used for a second phone line, are reversed, the
phone will work regardless. The phone uses a transformer or bridge circuit
that allows it to work either way. The DC voltage is only used through a
switch to determine the off-hook condition and for pulse (rotary) dialing.
Well... it's kinda hard unless you can get the leads for your meter on
both ends of the cable.
Another option might be one of the network cable testers. You connect
one part at the box that sends a tone on the line, and the other part
picks up the tone on the jack end.
The "tip" lead is usually green and with the line open, it will
not read a voltage, however, it will show a resistance to a
earth ground, such as a water pipe, the safety 3rd pin on an AC
outlet (be carefull) or the plate screw on an outlet or switch
(assuming metal boxes in a grounded system). The tip side can
also be white/'color' (more white than 'color') of a multipair
cable where 'color' is blue, orange, green, etc. Lost yet? It
can get worse. Some multipair cables have a pair color with 1
white and 2 white bands, i.e. blue/1white and blue/2white, where
blue/1white is the tip. Onto the 'ring' side. It is usally red
.... get it, ring ... red, r....r. It, with the line open is
at -48 volts to ground, however, as most central office -48
volts is actually at about -52, it will usually read -52 or
thereabouts. With the multipair cables the 'ring' side will be
the blue/white (more blue than white), or orange/white, etc. Or
it will be the 2white side of the pair when it is marked with
the 1white and 2white markings. I hope I didn't confuse the
issue too much.
> This WAS the message "Phone makes terrible sound w/ ans machine"
> I am now checking the phone line, but dont have one of those little
> LED testers. The green and red wires are connected to the correct
> screws on both ends, but there could be a splice in the crawl space
> under the house, and I am not crawling under there in this cold
> I have a digital, and an analog Multimeter. How can I test to be sure
> the polarity is correct using either of these meters?
The ring is red or ridged, readable to ground, and it terminates on the
right. That little limerick is to help new folks remember that it is
the ring side of the line that is red and will measure ~48 volts to
ground using a high impedance meter such as your digital multimeter.
Run a three wire extension cord from a known grounded receptacle outlet
to the vicinity of the telephone jack in question. Using the extension
cords equipment grounding conductor as a reference measure the DC
voltage on both conductors of each pair. The one that shows 48 volts DC
relative to ground is the ring which in four conductor jk wire is the
red or the yellow wire. The green or black wires should read a
relatively low voltage to ground because if the standard pattern was
followed they are the tip conductors of each pair but the exact value
will not be consistent unless your home has an unusually good grounding
electrode system with an impedance to ground of under five ohms. The
names tip and ring come from the parts of a standard 1/4" phone plug
such as the ones found on good quality stereo head sets. The tip is
battery positive which is grounded at the exchange in telephone
practice. The ring is battery negative which is forty eight volts
relative to the ring and to earth ground. The polarity can also be
checked with either meter by measuring between the red and green or the
yellow and black and observing the polarity indicator of the digital
meter or the needle deflection of the analog meter. With the meters
common (black) lead on the ring conductor and its positive (red) lead on
the tip conductor the meter should indicate a positive voltage. If you
put each lead on the color that does not match in each pair you should
get a positive voltage indication.
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