Make a 302 sound as good as a 500?

[rdelius]

If the set is not wired with a network or is miswired   there will DC flowing through the lb1 or u1 and the sound will be weak. The varistor across the capsule shunts the excess voltage  .Cut one of the varistor wires ans see if the sound gets louder. Make sure you can resolder  it .I dont recomend removing the varistor or risk loud pops in your ear.

[Lewes2]

Thanks ,Ken and Rdelius - I've check continuity from the element to  the phone  - no problem there.

I don't have lo volume, I the phone is dead, no sound whatsoever. 

Doing more test later this afternoon. 

Chuck-

[Dan/Panther]

Did anyone suggest, he remove the receiver element, and lightly tap it on a hard surface, to loosen up the carbon ?
D/P

[dsk]

Absolutely dead, looks like we have to test parts, or modules one by one.

Handset, test: remove transmitter and receiver and test as this diagram.
(If you take the hand set and cord as one module, you will test  cord and handset with components.


  |---------------------------------------------------------------------------|
  |                                                                                                 |
  |------------ battery -----transmitter------receiver---------------------|

polarities does not matter 3-4.5V battery will be OK!

If OK  connect W and BK to the dial, connect the phone to the line (or battery) and listen for dial tone (or hearing yourselves). Dialing will probably not work. IF OK connect the common wire R to the induction coil's R (Not to dial R)

This diagram should work:
dsk

[poplar1]

Ken nailed it. Chuck said that it is an intermittent problem with the short jumpers going to the receiver element.