There is a sound in the handle of the old landline phone, but the horn doesn't ring.

There are four solutions to the problem that the telephone handle of the old landline has a sound horn but does not ring.

1. First, visually check whether the external parts of the telephone, such as external cord, handle helix and plug-in, are firm, whether the telephone screws and other fasteners are loose, whether there is noise when shaking, whether the fork spring switch is pressed flexibly, whether the ringing volume switch, P/T dial-up changeover switch, anti-theft switch and receiving volume adjustment switch are in normal positions, and whether the keys are stuck.

2. Use multimeter 100V DC voltage to measure the voltage at both ends of the telephone external junction box. For digital program-controlled switches, the normal feed voltage is about 48V when hanging up. If it is lower than 44V, it may be that the fork spring switch or ringing circuit is abnormal. When off-hook, the normal feed voltage is 6 ~ 10V. Too high or too low indicates that the dialing circuit and the call circuit are partially open or short-circuited.

3. The AC voltage of the ringing signal input to the telephone should not be less than 50V. If it is lower than 40V, the ringing circuit is faulty. You can also test the ringing function with the ring back tone provided by the SPC exchange. The method is to dial "190" after the phone goes off-hook and then hang up. If the ringing circuit is normal, self-dialing ringing should be issued.

When the pulse is dialed, the bell rings. This is caused by the collision between the primary and secondary windings of the ringing output transformer. This fault is because after the phone goes off-hook, there is a DC feed current passing through the ringing integrated circuit. When the external terminal voltage is low after off-hook, the receiver will not ring, but when the pulse dialing is yes, the pulse voltage amplitude is large enough to make the receiver ring. Detect the suppression circuit board and solder joint at the output end of ringing integrated circuit. If there is no collision, replace the transformer.