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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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28th Dec 2017, 10:15 am | #21 |
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Re: GEC 1000 phone not working properly?
This is at my house
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28th Dec 2017, 10:29 am | #22 |
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Re: GEC 1000 phone not working properly?
Interesting... You should read a nominal 50V d.c. across the line with the telephone on-hook. This is the d.c. voltage across the incoming line pair to the premises.
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28th Dec 2017, 10:31 am | #23 |
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Re: GEC 1000 phone not working properly?
This is how I've connected my Ericsson N1026A (similar to yours) and it works.
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28th Dec 2017, 10:33 am | #24 |
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Re: GEC 1000 phone not working properly?
Phew! Now check at your mum's. 4.2V is a wee bit on the low side but should still work with a carbon mic in place. I was expecting something more like 8 - 12V. If your phone has a T21A electret mic insert and the off-hook voltage is too low, the mic will not work. They need at least 4.5V to drive them.
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28th Dec 2017, 10:49 am | #25 |
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Re: GEC 1000 phone not working properly?
Note, however, that the 'off-hook' d.c. voltage will change from (typically) 8V 'fresh' off-hook (dial tone) dropping to 5V (typically) when 'number unobtainable' tone cuts in, and will sit (typically) at 8.5V when a call is initiated.
These figures are from my BT line using a 332 telephone.
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28th Dec 2017, 11:12 am | #26 |
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Re: GEC 1000 phone not working properly?
Looking at the diagram it says on note 4 to fit a 100ohm Resistor for reduced volume which mine has so my guessing by fitting a 300ohm resistor like it says on the diagram it will increase the volume,
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28th Dec 2017, 11:22 am | #27 |
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Re: GEC 1000 phone not working properly?
Ok I had a better mic fitted so it would work better was my plan, I don’t know what mic it is but here’s a photo, what would cause the voltage to be to low ? I have a 332 also that has the original mic so next time I go to my mums I’ll test the voltage and the other phone,
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28th Dec 2017, 11:24 am | #28 |
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Re: GEC 1000 phone not working properly?
Here’s the new mic
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28th Dec 2017, 11:47 am | #29 | ||
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Re: GEC 1000 phone not working properly?
Quote:
Quote:
Does your mum live a long way from the exchange?
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28th Dec 2017, 12:11 pm | #30 |
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Re: GEC 1000 phone not working properly?
My mum lives in a village miles from anywhere, so I’ve no idea where the exchange is, I’ll short the low volume thing out and see how that improves the volume
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28th Dec 2017, 12:12 pm | #31 |
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Re: GEC 1000 phone not working properly?
That certainly looks like an electret transmitter inset 21A. As Russell says, the off-hook line voltage may be marginal for it to operate.
If you have a 300Ω (or more probably 330Ω as a standard value) available, there would be no harm in tryin the substitution, but I can't see that doing so would increase the operating voltage of the transmitter.
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28th Dec 2017, 12:14 pm | #32 |
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Re: GEC 1000 phone not working properly?
If increasing the resistance is supposed to increase the volume, I don't think shorting it out is going to be productive.
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28th Dec 2017, 12:31 pm | #33 |
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Re: GEC 1000 phone not working properly?
I removed the resister and put a piece of wire in its place and no dial tone so I’ll get a 300ohm one instead,
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28th Dec 2017, 1:11 pm | #34 |
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Re: GEC 1000 phone not working properly?
Will this type of mic fit ? If not can someone help me with what will fit as I have no idea what was fitted originally, the one from the 332 won’t fit,
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28th Dec 2017, 1:19 pm | #35 |
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Re: GEC 1000 phone not working properly?
Here’s a photo I’ve found online
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28th Dec 2017, 2:00 pm | #36 |
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Re: GEC 1000 phone not working properly?
D'oh! Misread it!
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28th Dec 2017, 2:14 pm | #37 |
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Re: GEC 1000 phone not working properly?
That won't fit. You need an 'Insert No:13'. You'll also need a sprung pin to fit in the back of the mic to attach the wire to, and your mic will need to be a version with a stud attached around the periphery of the 'flying saucer' to fit the other lead to. The GEC1000 and the original 706 instruments had these mics fitted as well as the 300 series instruments.
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28th Dec 2017, 2:25 pm | #38 |
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Re: GEC 1000 phone not working properly?
So I need to speak to the chap that fitted it and hope he still has them,
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28th Dec 2017, 3:00 pm | #39 |
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Re: GEC 1000 phone not working properly?
are you sure ? From what I’ve seen online this is a type 3 handset which takes the number 16 microphone,
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28th Dec 2017, 4:48 pm | #40 |
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Re: GEC 1000 phone not working properly?
If that's the handset you have, I think you are correct about the inset no. 16. I was expecting (and I assume Russell was too) that your 'phone would be fitted with handset no. 164 into which the insets shown by Russell would fit.
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