Quote:
Originally Posted by bigus01
'This has the result of reversing the polarity in the handset...'
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Don't worry about polarities in handsets. This is unimportant. The line polarity will change under certain circumstances anyway, and the T21A contains a bridge rectifier so it will work either way.
Can you confirm the following re: your handset wiring?
*That the common connection to both microphone and receiver is connected to terminal 5 on the telephone terminal block.
*That the connection unique to the receiver is connected to terminal 6 on the telephone terminal block.
*That the connection unique to the microphone is connected to terminal 4 on the telephone terminal block.
*That when the telephone is off-hook, there is no d.c. voltage (measure and say what it reads) across terminals 5 and 6 of the telephone terminal block.