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Old 26th Oct 2014, 12:40 pm   #1
Ryan_1993
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Default 332 Bakelite Telephone Microphone issue

Hello all,

I have just purchased a new electronic microphone for a family friends GPO 328 telephone. I purchased it from AntiqueTelephones.com and currently have one in my 232 telephone working perfectly fine. I wired as per instructions, which didn't work, I then followed this guide (http://antiquephones.blogspot.co.uk/...-bakelite.html)which again didn't work, the Microphone simply is not being detected.

I also swapped handsets with my 232 and vice versa, both handsets worked with the microphone on the 232, but as soon as I connect them to the 328 the Microphones no longer work, all I can do is hear a dial tone.

I have no idea what else to try the wiring in the phone seems correct and nothing seems incorrect or out of place. Is there anything else to try?

Thanks, Ryan
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Old 26th Oct 2014, 3:12 pm   #2
russell_w_b
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Default Re: 332 Bakelite Telephone Microphone issue

Does your handset work with the traditional carbon inset mic?
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Old 27th Oct 2014, 9:57 pm   #3
dagskarlsen
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Default Re: 332 Bakelite Telephone Microphone issue

I blieve removing of the transmitter should break dial tone on the 328 (Wiring diagram N 428 here) http://www.samhallas.co.uk/repositor.../0000/N428.pdf

Some electronic replacement transmitters are polarity sensitive (Try to switch red and white wire) some demands a voltage of at least5 V across the transmitter.

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Old 28th Oct 2014, 4:34 pm   #4
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Default Re: 332 Bakelite Telephone Microphone issue

I have tried that and it doesn't work on the 328. I have the same type of mic fitted inside of my Bakelite 232 and it works perfectly fine, and I have swapped both miss over they both work inside the 232 handset.
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Old 28th Oct 2014, 4:34 pm   #5
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Default Re: 332 Bakelite Telephone Microphone issue

Quote:
Originally Posted by russell_w_b View Post
Does your handset work with the traditional carbon inset mic?
the Carbon mic was totally dead and it never worked, the one in my 232 was the same though so that never worried me.
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Old 28th Oct 2014, 5:37 pm   #6
Dave Moll
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Default Re: 332 Bakelite Telephone Microphone issue

If the 328 has never worked, it sounds as though the problem lies elsewhere than the transmitter. As you are getting dial tone, it would appear that you have a loop. My first to check would be whether the dial-off-normal contacts across the transmitter are opening when the dial returns to normal (rest) position. If not, the transmitter will be shorted out.
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Old 28th Oct 2014, 6:57 pm   #7
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Default Re: 332 Bakelite Telephone Microphone issue

Try to connect the handset direct to the line, just leave the common wire unused.

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