Telephone troubles; their location and remedy

Front matter

Class_ T ^fe345 '

Book_ .V\ fS4 _

Copyright N°_

Contents

CHAPTER. PAGE.

I. Direct Line. 1

II. Two Party Line. 14

CHAPTER I. Bell Doesn’t Ring at all

May be caused by any of following:

1st. Condenser open.

2d. Ringer open.

3d. Hook contacts crossed.

4th. Desk stand cords or induction coil crossed.

5th. Extention bell open.

6th. Ringer short-circuited.

7th. Trouble at central office.

1st. When condenser is open you will get weak hook clicks and side tones and hearing very weak. Prove by short-circuiting the condenser at the lugs with a test cord, which should make the ring of the bell and hearing O. K.

(While the condenser ' is short-circuited you will get only one hook click.)

*Where reference is made to “hook clicks” in these in¬ structions, the instrument is understood to be a desk stand, wall sets are so connected as to give only one hook click on raising or lowering the hook.

When reference is made to the red, white or green strand of the desk stand cord, it is understood that the red goes to

TELEPHONE TROUBLES.

2d. Only one hook click, the side tones normal, and the failure of the ringer armature to move when you. raise or lower the hook, indicates that the ringer is open.

Prove by replacing the receiver on the hook and then bridge across the condenser lugs with your head receiver; if you do not get a good click every time you make contact, the ringer is open.

Or you can make the following test; open the strap at the top of the bell, then short-circuit the condenser lugs with a test cord; then connect one side of your head receiver to one of the line binding posts, and feel with the other side on the terminals of the ringer; if you get battery on one terminal and not on the other the ringer is certainly open.

3d. Only one hook click, side tones normal, failure of the ringer armature to move when you raise and lower the hook, and the receiver in circuit while the hook is down, indicates that the hook contacts are crossed together. When this is the case, the bell will ring poorly or not at all, and the ring can be heard in the receiver when the hook is down. Open the receiver circuit at one of the receiver binding posts, this should allow the bell to ring all right.

4th. Red and white strands of desk stand cord

the hook, the white to the receiver and the green to the transmitter; using the standard Western Electric cord.

When reference is made to L 1 L 2 orG 1 you will find them on diagram No. 1 or No. 2. When reference is made to “A” or “B” you will find them on diagram No. 3.

DIRECT LINE.

or primary and secondary of induction coil crossed together will generally cut down hearing; it may or may not cause only one hook click, and may or may not put battery through the receiver, and may wholly or only partly prevent the bell from ringing. Disconnect the strap on top of the bell and test with your head receiver from the G post to the L 2 post; if you get battery there is a cross; disconnect the red and white strands of the desk stand cord, this will show whether the trouble is in the desk stand cord or in the bell. If it is in the bell, dis¬ connect No. 2 and No. 4 terminals of the induction coil, and test again, to prove certainly that the trouble is in the coil itself and not in the wiring.

5th. If there is an auxiliary bell, and it is open, the set will test as though it had an open ringer. Test by short-circuiting the L 2 and G posts, which cuts out the auxiliary bell and makes it a straight set for the time being.

6th. If the ringer is short-circuited you will get battery through the receiver, which .can be detected by listening while you short-circuit the receiver binding posts with your screw driver blade. To prove, disconnect the bridge from the top of the bell, and connect the two line wires to the L 2 and G posts instead of the L 2 and posts; short-circuit the condenser lugs with a test cord, and then bridge your head receiver across the ringer terminals; if the ringer is all right you will get a heavy click, if it is completely short-circuited you will get no click at all, if it is partially short-circuited you will get a partial click.

TELEPHONE TROUBLES.

Bell Rings Weakly.

May be caused by:

Poor adjustment of armature or gongs.

Pivot screws too loose or too tight.

Clapper rubbing on guard.

Wiring interfering with the clapper stem.

“ Whiskers ” on the magnet heads.

Magnet heads sticky or gummy.

Desk stand cord, induction coil, or hook contacts crossed.

One or both coils of the ringer partially short-circuited.

Polarizing magnet weak.

Carbons in protector dirty and generator current jumping across them.

Trouble at the central office.

Bridge on the Line, Steady Light at Central Office.

Prove whether the trouble is in the instrument or not by disconnecting both sides of the line at the top of the bell and going in with your head receiver. If you get central the trouble is in the instrument and the same will be found either in the wiring, desk stand cords, or the hook. If opening the strap (see diagram No. 1) does clear the trouble, the leak is across through the ringer, and must be due to:

1. Receiver contact of hook not breaking. If this is the case, opening the receiver circuit at one of the receiver binding posts will clear the trouble temporarily.

DIRECT LINE.

2. White and green strands of the desk stand cord crossed together. If this is the trouble, dis¬ connecting the cords from the bell will clear it.

3. The condenser must be short-circuited if the trouble is not in the hook or cords; if the condenser is completely short-circuited, there will be but one

TELEPHONE TROUBLES.

hook click, but often there is enough resistance in a condenser short-circuit to give both hook clicks. To make sure that the trouble is in the condensfer itself, and not in the wiring, disconnect one terminal of the condenser and go in series with your head receiver.

Instrument Entirely Dead, Nothing can be Heard in the Receiver.

See first that you have battery at the top of the bell.

The trouble may be due to:

1. Receiver circuit open.

2. Receiver short-circuited.

1. If there is an open in the receiver circuit, it may be in either the receiver itself, the receiver cord, the white strand of the desk stand cord, the receiver contact of the hook, or the secondary; bridge your head receiver successively around these parts, when you bridge around the open you will get the side tones in the head receiver. To prove whether a receiver is short-circuited or not, connect your head receiver in series with it; if the head receiver responds while another receiver in series with it does not, the other one cannot be open, and therefore, must be short-circuited.

Transmitter out of Circuit, but Hearing not Entirely Cut Out.

May be caused by:

1. Open in green strand of desk stand cord, transmitter or transmitter wiring.

DIRECT LINE.

2. Transmitter short-circuited.

3. Red and white strands of desk stand cord crossed together.

1. No hook clicks, transmitter entirely dead, but can hear induction on the line, and can hear the effect of short-circuiting the line at the top of the bell, indicates an open. Locate by connecting one terminal of your head receiver to the L t post, and feeling with the other terminal successively on the several points of the transmitter circuit from the L a post to the hook; as soon as you pass the open you will cease to get battery through the head receiver.

2. Strong hook clicks, transmitter entirely or nearly dead, but can hear induction on the line and the effect of short-circaiting the line at the top of the bell, indicates transmitter short-circuited. Open at the transmitter and put your head receiver in series to see whether the trouble is a short-circuit inside of the transmitter head, or a cross of the trans¬ mitter cord or the green strand of the desk stand cord with the frame of the desk stand.

3. Two hook clicks, but the transmitter dead and cannot hear induction on the line, and cannot hear the effect of short-circuiting the line at the top of the bell, andbell rings poorly ornot at all, indicates red and white strands of the desk stand cord crossed together which short circuits the receiver while the hook is up. Disconnect the strap at the top of the bell, and test as previously directed from the G post to the L 2 post; if you get battery the cord is crossed.

TELEPHONE TROUBLES.

Transmission Poor.

May be due to:

1. Transmitter packed or otherwise bad.

2. Red strand of desk stand cord, primary, or hook contact open (in which case the hearing will also be poor).

3. Primary or secondary reversed.

4. Primary and secondary crossed together( this will also affect the hearing).

5. High resistance in the line or instrument.

1. When a transmitter is believed to be packed, call the wire chief, being very careful not to shake it up or jar it, and get him to note the way it transmits; then shake it up thoroughly, and see what the effect is on transmission. When a transmitter is suspected of packing but you fail to catch it in the act, you can sometimes pack it by blowing gently into the mouth piece for a minute or so; but in making this test be careful not to condemn a good instrument, as almost any transmitter is liable to a certain amount of packing, and will come up stronger immediately after having been shaken up.

When a transmitter is suspected of being otherwise defective a sure test can be made by temporarily swapping faces with some other instrument that is all right.

2. Only one hook click and weak side tones indicate primary or red cord open. Connect one terminal of your head receiver to the L 2 post and test with the other successively on the L t post, No. 1 and No. 2 terminals of the induction coil, red cord

DIRECT LINE.

post in desk stand, hook spring, and hook; as soon as you pass the open you will not get battery.

3. Examine 1 and 2, and 3 and 4 of the coil to see that they are not reversed, that is, see that the numbers of the coil terminals correspond with the numbers of the lugs that they connect to. If the coil is reversed internally, so that the numbers correspond but nevertheless one of the windings is wrong, it can only be detected by the man at the other end. Call up the wire chief or go to another instrument yourself and listen to the transmission from the suspected instrument; if the coihis reversed the transmission will be muffled. Prove by reversing either the primary or the secondary, which should clear the trouble.

4. Test as previously directed for primary and secondary crossed together.

5. Get the wire chief to test the resistance of the line, or test it yourself as follows: Bridge your lamp on at the top of the instrument, the lamp will bum rather dimly on an ordinary line, very dimly if it is a long line, or an extension line from a private branch exchange with a high resistance drops and retardation coils. (In the latter case the test can be made better after the operator has plugged up the line.) Next connect your line in series with the instrument, take the receiver off the hook, and compare the brightness of the lamp while the instru¬ ment is in circuit, and while it is cut out by short-circuiting the L x and L 2 posts. If there is much difference noticed there is a high resistance in the instrument. Forty ohms is a fair average for the resistance of a central battery instrument, but it may be higher or may be lower, it may run below

30 ohms. About 16 ohms of this is in the primary and the rest is in the transmitter. To prove that there is no resistance in the soldered connections

DIRECT LINE.

or hook contact, short-circuit both the primary and the transmitter; this should cut out all of the resistance and completely short-circuit the instru¬ ment, so that you will get no battery from L t to L 2 posts when the hook is up.

The resistance of a 24 volt test lamp is somewhere about 400 ohms cold and 240 ohms hot.

Hearing Poor.

May be due to:

1. Receiver bad.

2. Receiver cord or white strand of desk stand cord bad.

3. Condenser open.

4. Primary and secondary crossed together.

5. Primary short-circuited.

6. Secondary short-circuited.

7. High resistance in secondary circuit.

There will be two hook clicks with any of the above troubles, but one of the clicks may be cut down more or less.

1. Examine the receiver for dented diaphragms, “ whiskers ” on the magnets, magnets too close to diaphragm, or magnets weak; test by putting your head receiver in series with it and comparing the hearing.

2. To test the receiver cord and the white strand of the desk stand cord, put battery through them and listen in the receiver for a cut out or scratchy sound while you shake them. Short-circuiting the condenser with a test cord puts battery through the receiver and its cords when the hook is up.

TELEPHONE TROUBLES.

3. If the condenser is open the ringer usually will not ring, but sometimes you can ring through a condenser that you cannot hear through at all. Test by short-circuiting it with a test cord.

4. Primary and secondary crossed together will usually short-circuit the ringer and prevent your getting a ring. Test as previously directed.

5. If the primary is short-circuited bridge your head receiver around it; you will get no click when the hook comes up, and no side tones. If the primary is all right you will get both clicks and side tones in your head receiver.

6. A short-circuited secondary can be tested by exactly the same method as is given above for testing the primary.

The above tests work very well if the primary or secondary is completely or nearly short-circuited, but if the short circuit is only partial it is very hard to detect. If you are .in doubt, change the bell temporarily for another bell that is all right or change the induction coil, and compare results.

7. To test for a high resistance in the secondary circuit, put battery through it by short-circuiting the condenser with a test cord while the hook up, then listen in the receiver while you short-circuit successively the receiver hook contact, the two sides of the receiver cord, the white strand of the desk stand cord, the wiring from receiver cord to secondary, from secondary to condenser, and from condenser to L 2 , and the secondary itself; when you short circuit out any part of the circuit that

DIRECT LINE.

contains resistance, such as the secondary itself, more battery will flow through the receiver, giving you a click.

An instrument in which the ringer is not connected, will, of course, give but one hook click.

Reversals in the connecting up of desk stand cords may cause only one hook click or poor hook clicks, poor transmission, poor hearing, transmitter nearly dead, etc., according to the combination in which the three strands of the cord are connected.

If the ground side of the line is open outside the set may be put in temporary service by working to a local ground.

If the induction coil is bad, temporary service can be given, i'f necessary, by putting the transmitter and receiver in series, and properly poling the receiver.

Chapter II. Two Party Line

No. 1 Set.

(The battery side of the line goes to the L 2 post.)

Gives two hook clicks, and can be tested in very much the same way as a straight set, but the following points should be remembered: on sets that ring to ground an open ground will, like ringer open, cause the bell not to ring and only one hook click.

Resistance in the ground may cause poor ring.

Reversal of the three wires on top of the bell may cause only one hook click, bell not to ring, and transmitter nearly dead.

Transmitter very poor may be caused by the ground side of the line being open outside. (You can still call the operator and talk, with difficulty through the ringer and ground.)

No. 2 Set.

Gives but one hook click, but otherwise can be tested in very much the same way as a straight set. Remember the following points:

On sets that ring to ground:

Ground open will prevent bell from ringing.

Resistance in the ground may cause poor ringing.

A ground on the ground side of the line may 14

TWO PARTY LINE.

cause the bell to ring poorly or not at all by takirg the generator current oh to ground before it reaches the instrument.

Condenser short-circuited will not only put a ground on the ground side of the line through the ringer, but on exchanges which use pulsating cur¬ rent for ringing will also cause bell to ring poorly or not at all.

Reversals of the three wires on top of the bell may cause two hook clicks, bell not to rmg, and transmitter nearly dead.

On two-party sets, to find reversals of the wires at the top of the bell, trace out the wire to the pro¬ tector, or else find out with your head receiver which one of the three wires is alive to both of the others, or to an independent ground. This one is the battery side of the line.

To test for reversal of the ground wire with the ground side of the line, bridge your head receiver from an independent ground to the two doubtful wires successively. You will get induction on the line wire, and none on the ground wire. Or, bridge your receiver from the battery side of the line to the other two wires successively; the one that gives the most induction in this case is the ground wire. Or again, test by bridging your lamp from the battery side of the line to the other two wires successively. If the ground is good, bridging to it will give a brighter lamp than bridging to the ground side of the line; only a little brighter if the line is short, much brighter if the line is long.

TELEPHONE TROUBLES .

The above is also the way to test for a poor ground. The resistance of the ground return back to the cen¬ tral office should be less than the return through the cable, therefore the lamp should bum brighter on the ground wire than on the ground side of the line; very little brighter if the line is short, much brighter if the line is long.

An extension bell open will prevent the main bell from ringing, just as in a straight set. Test by running a temporary ground, or by short-circuiting out the extension bell.

If you are in doubt when testing a two party set, disconnect the ground wire and strap the bell, making it a straight set temporarily, and then test the ringing, transmission, and hearing. A straight set will respond to all rings, direct, two-party, and four-party.

If on a two-party set the ground side of the line is open outside, temporary service may be given, if necessary, by working to the local ground.

If the ground is open, temporary service can be given, if necessary, by converting to a straight set; but in this case the bells will respond to both calls.

If second instrument is properly poled and bell rings when first station is being called, the trouble is probably due to party at first station taking his receiver off the hook before the operator has stopped ringing, and vice versa.

Chapter III. Four Party Set

(Diagram No. 3.)

Tests of the transmitting and hearing circuits can be made in very much the same manner as in a straight set. On account of the relay coil being bridged between No. 2 and No. 3 terminals of the induction coil, a four-party desk set, if in perfect order, will give two hook clicks, no matter how it is poled.

To make a perfectly sure test for primary and secondary crossed together, it is necessary to discon¬ nect one terminal of the relay winding; then with the receiver on the hook, test from the L 2 post to the secondary with your head receiver; if you get current there is a cross.

Reversals of the three wires at the top of the instru¬ ment may cause a variety of troubles, just as in the two-party sets.

Ringing Circuit.

Relay: Failure of the relay to come up when the operator rings may be caused by:

Condenser open.

Relay short-circuited or open.

Hook contacts, or red and white strands of defck 17

TELEPHONE TROUBLES.

stand cord, or primary and secondary of induction coil crossed together.

Primary open.

Trouble at central office.

Test just as though it was a straight set except when testing for relay short circuited, or for a cross between primary and secondary, (in which case you must open one terminal of the relay winding, as previously directed); and except when testing for relay open, which you can do by bridging your head receiver from L 2 post to No. 2 and No. 3 terminals of the induction coil successively; you should get strong battery on No. 2 terminal, if the relay is all right and a strong condenser discharge when you make contact, but a weak battery click when you break contact, on No. 3 terminal.

A ground on the ground side of the line may also prevent the relay from operating, by carrying the generator current off to ground before it reaches the instrument.

If the relay is held up, usually the lamp is kept burning at the central office also, and this means that current is flowing from the central office over the battery side of the line, passing through the relay winding, and returning to the central office over the ground side of the line, or through the ground wire and ground. This condition may be due to: 1st. Winding of relay crossed with frame. Test by disconnecting the “ A ” or “ B ” terminals of the ringer from “ L 2 ” which should release the relay. 2d. As in the case of current through the ringer of a

FOUR PARTY SET.

straight set, the trouble may be caused by receiver contact of hook not breaking, white and green

Line strands of desk stand cord crossed together, condenser short-circuited. Test as though it was a straight set.

TELEPHONE TROUBLES.

If the relay vibrates continuosly the winding is probably crossed with the frame. To find out whether this is the case, disconnect the ground wire, which should stop the vibrating.

If the relay “ jumps ” while the operator is ringing, instead of pulling up and staying up as long as the ringing current continues, the relay may be weak, due to a part of the winding being short-circuited out, or to some other cause; or there may be too many bells and relays on the line, so that, owing to the resistance of the line, not enough generator current will flow over it to divide up and give each bell and relay a proper amount of current; or there may be a slight ground on the line, which carries off a part of the ringing current.

To prove that a relay is all right:

1. Short-circuit the condenser; this should hold up the relay, by putting battery current through it.

2. Prove that the spring contact is not crossed with the frame as follows: Disconnect “ A ” and “ B ”, then connect the frame of the relay to battery with a test cord, and bridge from the spring contact to ground with your head receiver; if you get no current, there is no cross.

3. Prove that the winding is not crossed with the frame as follows: Disconnect “ A ” and “ B ” and then test with your head receiver from the frame to the L 2 posts; if you get no battery there is no cross.

Ringer: If the relay comes up, but the bell does not ring, the trouble may be due to:

Ringer poled wrong.

FOUR PARTY SET.

Bias spring too tight or too loose.

Ringer open.

Ground open.

Ringer short-circuited.

Bridging your head receiver across the ringer while the operator is ringing will show whether or not you are getting generator current on the term¬ inals of the ringer winding; going in series at the “ A ” and “ B ” terminal will show whether or not you are getting current through the ringer.

To prove whether a ringer is open or not, connect “ A ” to battery, hold the relay closed, and then test from “ B ” to ground'with your head receiver; if you get no current the circuit is open; prove that the open is in the ringer itself by testing direct from the two terminals of the winding successively.

The ground can be tested in the same manner as on a two-party set.

To prove that the ringer is short-circuited, connect “ A ” and “ B ” across the line, close the relay contact, and bridge across the terminals of the ringer winding with your head receiver; if you get no click the ringer must be short circuited; check this test by putting your head receiver in series with the* ringer, while it is connected across the line, and closing the relay contact; this should give you a strong click if the ringer is short-circuited.

Bell ringing weak may be due to:

Poor adjustment of armature.

Poor adjustment of bias spring.

Pivot screw too loose or too tight.

Clapper rubbing on guard.

Wiring interfering with clapper stem.

“ Whiskers ” on magnet head.

Magnet head sticky* or gummy.

Polarizing magnet weak.

One or both coils of ringer partially short-circuited.

Too many bells and relays on the line.

Ground on one side of line which takes part, of the generator current off to ground before it reaches the instrument.

Trouble at central office.

Earth currents.

To test for earth currents bridge your head re¬ ceiver from the ground side of the line to the ground; you should get no current; if you do get current you will probably find that it varies continually, being due to trolley cars; report the matter to the chief inspector. In making this test be sure that the line is not in use; if the receiver is off the hook at any station on the line you will get a false test.

Earth currents very often cause bell troubles on suburban stations, particularly those that lie near to trolley lines; but in the city, earth currents are seldom noticeable.

False rings may be caused by:

Very strong earth currents.

One coil of ringer short-circuited.

If a biased ringer has one coil short-circuited, then when it is poled for either 1st or 2nd stations it will respond to both rings; and likewise when poled for 3d or 4th stations it will ring with either current.

FOUR PARTY SET.

In the bell diagram No. 3 you will see that “ B connects to the spring contact of the relay, the frame of the relay connects to the biased side of the ringer, and the unbiased side of the ringer connects to A.

In the older bells, “ B ” connects direct to the biased side of the ringer; the unbiased side of the ringer connects to the spring contact of the relay, and the frame of the relay connects to “A.”

Therefore, in connecting an extension bell to a set that has no extension bell binding posts, connect one side of the wire to the frame screw of the relay, under the bottom of the set, and the other side to the post at the top of the bell that “ A ” connects with. Or solder one of the extension bell wires to the spring contact of the relay, and connect the other to the post at the top of the bell that B con¬ nects with. In every case the auxiliary bell must be connected across the terminals of the ringer without being bridged around the break of the relay. Pole the extension bell by reversing the wires either at the be’ll or at the set.

Ringer Adjustments: In adjusting a biased ringer find out the two points where the bell ceases to ring on account of ther bias spring being too tight and too loose, and adjust the spring half way between these points. To locate them, slack off the bias spring until it has no tension at all, and then get the oper¬ ator to ring while you tighten up the spring, and note the point at which the bell commences to ring; continue to tighten the spring until the bell ceases to ring; by making the adjustment half-way between

TELEPHONE TROUBLES.

these two limits, you will have a margin both ways, so that if the generator rises a little above or falls a little below its proper voltage, the bell will still ring.