After the telephone outlet articulated telephone, no dial tone, but other normal function. qk7service manual download site
 qk7service manual download site
The reason mainly has: qk7service manual download site
 qk7service manual download site
1) telephone interface damage; qk7service manual download site
 qk7service manual download site
2) by fax/phone conversion control circuit has a problem. In the case of without electrical commissioning, found the phone function and listen to calls, telephone interface normal, focusing on fax/phone conversion control circuit. Its working principle is: when I finished with each other after the fax number, the other off-hook signal response, and began to receive and send the manuscripts, the IC1 (93) of the output high level feet, make the Q311 conduction, relay RL301 suction, telephone silent; When don't accept fax machine, send the manuscripts, the system circuit IC1 (93) of the foot as the low level, Q311 cut-off, relay RL301 doesn't work, telephone directly on the perimeter. qk7service manual download site
 qk7service manual download site
 qk7service manual download site
According to the principle of analysis, judgement relay RL301 misoperation. Carefully check the part of the circuit, found Q311 (DTC143E) has breakdown, resulting in the failure. Processing method: after replacing DTC143E commissioning, troubleshooting.qk7service manual download site