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Old 15th Nov 2017, 5:35 pm   #56
russell_w_b
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Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
Default Re: GPO 332 transmitter issue

Quote:
Originally Posted by bigus01 View Post
Open circuits all round
It seems you need dial surgery! Your 'dial-off-normal' contacts should ONLY be closed when the dial is being rotated. Yours are closed and are shorting out the mic. Details on how to maintain dials are here.

As a final check, configure your telephone as a 'central battery' model (without a dial) by disconnecting the dial entirely and shorting together terminals T4 and T5 on the dial terminal strip.

Refit the carbon mic, plug the tele in and see if you can hear dial tone, and side-tone from blowing into the mic. If so, try your T21A mic again and see if that works similarly.
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