|
Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
|
Thread Tools |
21st Jun 2015, 5:04 pm | #41 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
Mic aka TRANSMITTER swop. Not RECEIVER.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
21st Jun 2015, 5:13 pm | #42 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
Ok, I did the receiver swap. I don't think it made any difference actually. However, while I was tinkering I tried dialling a number, but instead of taking my finger out of the dial for it to return, I left my finger in and gently pushed as the dial went back. Hey presto, a perfectly dialled 123 to the speaking clock. Followed, with a bit of practice, with a perfectly dialled 11 digit number to my mobile (twice)!
I think I said somewhere before that when I tried my pulse dialling push-button phone it seemed to dial the pulses faster than I remember from years ago. Well it seems my exchange isn't too fussy as long as they come quite fast. So now I've got the problem tracked down (at least on the ivory phone) to a mechanical fault on the dial, how do I speed the dial up a bit? It's mostly plastic parts and all looks very clean. No sign of oil or grease anywhere. I'm thinking a light lubrication might make it just that little bit faster so it works, but wanted to check with you guys first. If that doesn't work / shouldn't be done, what should I do to speed up the dial a little? Andy. |
21st Jun 2015, 5:14 pm | #43 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
On thought that's crossed my mind is that the "faulty" mic may be a replacement Electret type which may well present infinite resistance when unpowered.
Electret mics are marked 21A.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
21st Jun 2015, 5:14 pm | #44 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
|
21st Jun 2015, 5:16 pm | #45 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
The "dirty" method of speeding up a dial was to squeeze together the legs of the governor using pliers. It really ought to be cleaned and relubricated though.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
21st Jun 2015, 5:17 pm | #46 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
It certainly looks different through the holes in the mouthpiece. The other one is metal, but this one appears to be black plastic, so I'm guessing it could be Electret. I'll have a more determined go at unscrewing the cover. In the meantime I've discovered both receivers work perfectly.
|
21st Jun 2015, 5:21 pm | #47 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
I've seen the squeezing of the governor mentioned in some official looking sheets, which i assume were issued to engineers. It seems a bit heath robinson though. I also don't think it needs that much adjustment. I'll go down the cleaning / lubricating route. I've got a little syringe thingy full of clock and watch oil somewhere, which I think should do the job. It's plastic safe at least.
|
21st Jun 2015, 5:22 pm | #48 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
If all else fails get a jam jar lid remover from a mobility shop.
http://www.amazon.co.uk/EasyJar-Jam-.../dp/B007Z20ZPQ Or clamp a "Jubilee" clip round it with a bit of old inner tube used to protect the plastic. The screw of the clip means you can get a more positive grip.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
21st Jun 2015, 8:14 pm | #49 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
I got the cover off with a jam jar lid remover. It looks like an Electret mic to me. It's certainly not the normal mic in a receiver. It's blue and black plastic and stamped with a small 21A as you said.
Andy. |
21st Jun 2015, 8:26 pm | #50 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
Definitely an electret then. Something I hadn't considered, as all my old phones still have carbon mics.
That would explain your infinite resistance reading. I assume the mic works? You seem to have sussed the problem. A slow dial.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
21st Jun 2015, 8:50 pm | #51 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
Yep, everything is working well now, thanks to the pointers from you and the others on here.
I just need to find the clock oil and I'm pretty sure that will bring the dials back up to speed. Andy. |
22nd Jun 2015, 7:09 pm | #52 |
Retired Dormant Member
Join Date: Jun 2015
Location: Chesterfield, Derbyshire, UK.
Posts: 110
|
Re: Need help tracking down 746 dial out problem
Just updating this thread to bring the story to a close. Both phones are now working perfectly. I gave the dial mechanisms a light oil, but I did also have to adjust the governor arms a little in the end.
It's also amazing how much quieter and smoother the dials are with a bit of oil on. Andy |
22nd Jun 2015, 7:18 pm | #53 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
|
Re: Need help tracking down 746 dial out problem
A happy ending then.
Is it GPOese to refer to the handset as the receiver? I found it a bit confusing since it comprises both transmitter (microphone) and receiver (earpiece) in my thoughts.
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
22nd Jun 2015, 7:21 pm | #54 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
|
Re: Need help tracking down 746 dial out problem
The mic was generally referred to as a transmitter. Together with the receiver it was mounted in a handset.
Replacing the receiver, ie hanging u,p probably originated in the days of separate receivers as in candlestick phones.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
22nd Jun 2015, 11:19 pm | #55 |
Heptode
Join Date: Apr 2011
Location: Edinburgh, UK.
Posts: 805
|
Re: Need help tracking down 746 dial out problem
|