atcomsystems.ca/forum Forums General General Telephone & Systems Information WEAK BELL IN OLD PHONE

My 2cents, I've read thru everyones comments, As soon as I read the first one, I was thinking that maybe the phone was modified for Diode ringing? It's been too long ago for me to remember the correct name for it?

also, the fact that the OP said something about the phone just going ding-ding, instead of RING-RING .

nonameyet,

im sorry. i meant that the ringer didnt ring loud, like most old bell type phones do. it rang normal, just weak, not loud as i remember them ringing. im still pluging away at it:)...bob

Nonameyet -

Matrix ringing was, what I think you're talking about. It involved removing the capacitor from the bell circuit and was really only used on common bell (Key system) circuits. On a single line appearance without the capacitor the bell would hold up the line.

Sam

just what exactly does the cap do? does it filter noise that may occur on the callers receiver from the ac voltage ringing the bells?

bob

The bell's coil resistance is around 1000 ohms. Placing the bell coil across the phone line, the central office would probably think you had the telephone off-hook because of direct current flow. The capacitor prevents the flow of direct current. Because of the capacitor's ability to pass alternating current (90-130 VAC, 20-30 Htz), the bell rings without the central office thinking you have the phone off-hook. However, capacitors have AC resistance, called impedance. Capacitors can fail or degrade 3 different ways 1. Short and electrically appear to be a wire. 2. Open and electrically look like nothing. 3. Slowly degrade, becoming a lower and lower value making their impedance rise. Ringer capacitors, as an example, start at .47uf-.5uf. As they degrade to, as an example, .22uf, their impedance, or AC resistance, increases. All other things being equal, a rise in Impedance, or AC resistance, will result in a lower current flow. In the case of ringers, not as much 'power' is available to ring the bell. Hence, the bell is not as loud as it used to be. I know, TMI! John C.

By the way, putting another .47uf-.5uf capacitor in parallel with the exhisting .47uf-.5uf capacitor will lower the impedance, or AC resistance. If the original capacitor is in good condition, this may lower the impedance enough to cause the central office to think you answered the telephone during the 'ring', commonly referred to as 'ring-trip' among other names that we won't discuss. So, the phone rings once, generally not a full ring, and doesn't ring again. Depending on the SLIC (Subsciber Line Interface Circuit) in the Central Office, Slic Hut, PBX, or S/L port in a hybrid phone system, the SLIC may reset for another call, or lock-up, causing a continious busy signal to all callers. Again, TMI. John C.

Lots of good information here. However the most common cause of this problem is as follows:

If it is a bell telephone such as a 500 and the bell has two gongs. If you look at the clapper which, of course is located between the two gongs, you will see a thin wire tension spring. In the metal bracket where this spring rests there are two notches. Move the spring to the other notch and try this.

Jack we've already been down that road. Based on the age of the phone, it's probably got a tired bias spring, that needs a little TLC. Go back and check page 1, we've pretty much tried everything. John C.

jack, light,

i just purchased a new ringer for the phone. it rings alittle louder, not much tho, but seems to respond better, and i even tried the bias spring in both postions, no diff. im starting to think it may be the cap failing, makes sense how light discribed it. i might as well put an external cap across "a" and 'k", correct?, dont think it can hurt to try it for a test...bob

When I was in tech school the Instructor told us as far as the telephone was concerned capacitors were for blocking dc voltage.
Which the capacitor does in fact keep the ringer from being directly connected to Tip & Ring since ring voltage is AC.

But I think connecting the ringer directly to Tip & Ring (Bridged ringing) was only a problem in the dial pulse days. In those days if you did connect the ringer directly to Tip & Ring you often got bell "claps" when you dialed a number.
But if you reversed the bell leads the problem went away in most cases.

I learned all of these tricks when I was in the Air Force over seas and we just had to make do with what we had on hand to "get 'er done".