GPO 746 rotary dial sticks with the case on - UK Vintage Radio Repair and Restoration Discussion Forum

ThomasAdam · 15th Mar 2023, 12:50 am

Hey all,

I hope everyone's well.

I've been reading through the archives here hoping I'd find an answer to my question, but I do not think I found anything, so I'm hoping some kind soul(s) can help me.

I have a few GPO 746 phones, where the rotary dial moves freely and returns to its normal position just fine with the case off, yet as soon as I put the case back on the phone, the dial sticks and no longer rotates freely, and sticks.

By "sticks", I mean that no matter which number I select, be it "1" or "0", the dial refues to return to its original position -- if I nudge the dial, it kind if returns, but not quite.

Would anyone have any ideas as to what the problem could be? In each case, I have cleaned the govenor, and that appears to have helped, but has not solved the problem.

Pleasse feel free to point me to other posts, rather than rehash any information here if that's more appropriate!

Many thanks in advance.

Thomas

Roger Ramjet · 15th Mar 2023, 10:01 am

Hi Thomas,

746 cases can be tricky to refit & often need a bit of juggling plus ensuring the inner dial surround is aligned to the dial. The other thing to look out for is the dial locating tabs at the bottom plus the top screw bracket.... any misalignment here may stress the dial when cover refitted causing the problem you have.

Rog

Nickthedentist · 15th Mar 2023, 11:10 am

Hi Thomas and welcome.

I've got loads of 746s and never had that problem, but I agree with Roger that the cases often require quite a bit of force and jiggling to re-fit. I think the earlier 706 is much better in this respect.

Presumably, with the cover fitted, the dial's finger plate is not rubbing against the case or the dial surround. The dial surround should be a "floppy" fit in the case, and be able to be moved from side-to-side and up-and-down a bit. If someone's glued it on because the tabs have broken, it will be hard to get things to work reliably.

Is the "tongue" at the bottom front of the case properly engaged in the cutout in the base?

And when you've cleaned the governor, have you removed/refitted the governor cup? Its screw holes are oversized, allowing you to adjust its postion, and its precise position is critical for smooth and reliable running.

Could you post a picture of the underside of the phone with the cover fitted, and another side view showing how the finger plate pokes through the dial surround?

ThomasAdam · 16th Mar 2023, 12:18 pm

Quote:

Originally Posted by Nickthedentist

Could you post a picture of the underside of the phone with the cover fitted, and another side view showing how the finger plate pokes through the dial surround?

Hey Nick! Many thanks for your reply.

Attached are the photos you requested.

I also have a short video showing how the dial is getting stuck, which you can access here:

https://youtube.com/shorts/SQwdAtTwDkE

You'll note from the video how the dial sticks around number 5, and that once resistance is met, I just have to gently touch the case, and it rotates back to its starting position.

I can definitely feel the resistance though, so I suppose it is catching still, but this is the best I've managed to get it so far.

Thanks once again!

Thomas

Station X · 21st Mar 2023, 8:39 am

Standard cure for this was to loosen the screw at the top of the dial assembly which holds it to the "chassis". Then press gently on the dial to make sure the screw has bottomed in the 'U' shaped slot before retightening the screw. Also check that the clamping ring is correctly fitted over the flexible plastic case covering the dial mechanism.

If this doesn't work, as Nick says, check that the external rotating part of the dial is not jamming on the case or dial plate. If it isn't the dial mechanism is being distorted in some way.

EDIT. It may just be the picture, but it looks like that dial is in the wrong position and needs rotating relative to the case? '0' and '3' should be located roughly North to South. The vertical and horizontal lines on the dial label appear to be located correctly relative to the figures, but they should run NS/EW.

Nickthedentist · 21st Mar 2023, 8:46 am

Ah, looking at your underside pictures, I think the problem is that the protruding tab of the plastic case needs to be hooked under the metal base, not allowed to sit above it.

This is the correct position: https://www.modip.ac.uk/sites/defaul...?itok=0Y4REOip

Station X · 21st Mar 2023, 8:54 am

Well spotted Nick.

Nickthedentist · 21st Mar 2023, 1:44 pm

Thanks

The way I normally fit the covers on these is to hook the tab over the front of the metal base, then hinge the back of the case downwards.

It will foul against the top of the dial's finger plate, but jiggle the case around until it can be eased into the correct position. Sometimes, you need to use your fingers to support the dial surround so that it doesn't pop out of the case, and your other hand's fingers to flex the top of the finger plate fractionally.

If you find this daunting and tricky to achieve, remove the finger plate, fit the case, then re-fit the finger plate. If you choose to do this, do NOT lever off the dial centre, but use a suction cup or even a bit of very sticky tape to pull it off. Then remove the single slotted screw under the label.

Finally, after ensuring that none of the wires from the line cord/handset cord are trapped, tighten the screw at the back.

Graham will probably have a more elegant, "official" method...

Oldcodger · 7th Apr 2023, 5:17 pm

I found in my days on subs app fitting ( giving folks a phone to non GPO BLOKES) that it helped to use a small screwdriver ( No 1 to GPO blokes or small terminal to others) under the top part of dial ( 12 o'clock, looking at dial from front) to prise the cover over the dial. It helps if the screw at rear of base is held back before trying this. It can be daunting to those with only one phone, but is sometimes pays to be force full with 746. The dial ring on the phone is the cause of problems.

15th Mar 2023, 12:50 am	#1
ThomasAdam Diode Join Date: Mar 2023 Location: Devizes, Wiltshire, UK. Posts: 4	GPO 746 rotary dial sticks with the case on Hey all, I hope everyone's well. I've been reading through the archives here hoping I'd find an answer to my question, but I do not think I found anything, so I'm hoping some kind soul(s) can help me. I have a few GPO 746 phones, where the rotary dial moves freely and returns to its normal position just fine with the case off, yet as soon as I put the case back on the phone, the dial sticks and no longer rotates freely, and sticks. By "sticks", I mean that no matter which number I select, be it "1" or "0", the dial refues to return to its original position -- if I nudge the dial, it kind if returns, but not quite. Would anyone have any ideas as to what the problem could be? In each case, I have cleaned the govenor, and that appears to have helped, but has not solved the problem. Pleasse feel free to point me to other posts, rather than rehash any information here if that's more appropriate! Many thanks in advance. Thomas

15th Mar 2023, 10:01 am	#2
Roger Ramjet Heptode Join Date: Feb 2022 Location: Leicestershire, UK. Posts: 690	Re: GPO 746 rotary dial sticks with the case on Hi Thomas, 746 cases can be tricky to refit & often need a bit of juggling plus ensuring the inner dial surround is aligned to the dial. The other thing to look out for is the dial locating tabs at the bottom plus the top screw bracket.... any misalignment here may stress the dial when cover refitted causing the problem you have. Rog Last edited by Roger Ramjet; 15th Mar 2023 at 10:01 am. Reason: repeated word

15th Mar 2023, 11:10 am	#3
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,410	Re: GPO 746 rotary dial sticks with the case on Hi Thomas and welcome. I've got loads of 746s and never had that problem, but I agree with Roger that the cases often require quite a bit of force and jiggling to re-fit. I think the earlier 706 is much better in this respect. Presumably, with the cover fitted, the dial's finger plate is not rubbing against the case or the dial surround. The dial surround should be a "floppy" fit in the case, and be able to be moved from side-to-side and up-and-down a bit. If someone's glued it on because the tabs have broken, it will be hard to get things to work reliably. Is the "tongue" at the bottom front of the case properly engaged in the cutout in the base? And when you've cleaned the governor, have you removed/refitted the governor cup? Its screw holes are oversized, allowing you to adjust its postion, and its precise position is critical for smooth and reliable running. Could you post a picture of the underside of the phone with the cover fitted, and another side view showing how the finger plate pokes through the dial surround?

21st Mar 2023, 8:39 am	#5
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 20,464	Re: GPO 746 rotary dial sticks with the case on Standard cure for this was to loosen the screw at the top of the dial assembly which holds it to the "chassis". Then press gently on the dial to make sure the screw has bottomed in the 'U' shaped slot before retightening the screw. Also check that the clamping ring is correctly fitted over the flexible plastic case covering the dial mechanism. If this doesn't work, as Nick says, check that the external rotating part of the dial is not jamming on the case or dial plate. If it isn't the dial mechanism is being distorted in some way. EDIT. It may just be the picture, but it looks like that dial is in the wrong position and needs rotating relative to the case? '0' and '3' should be located roughly North to South. The vertical and horizontal lines on the dial label appear to be located correctly relative to the figures, but they should run NS/EW. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

21st Mar 2023, 8:46 am	#6
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,410	Re: GPO 746 rotary dial sticks with the case on Ah, looking at your underside pictures, I think the problem is that the protruding tab of the plastic case needs to be hooked under the metal base, not allowed to sit above it. This is the correct position: https://www.modip.ac.uk/sites/defaul...?itok=0Y4REOip Attached Thumbnails

21st Mar 2023, 8:54 am	#7
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 20,464	Re: GPO 746 rotary dial sticks with the case on Well spotted Nick. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

21st Mar 2023, 1:44 pm	#8
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,410	Re: GPO 746 rotary dial sticks with the case on Thanks The way I normally fit the covers on these is to hook the tab over the front of the metal base, then hinge the back of the case downwards. It will foul against the top of the dial's finger plate, but jiggle the case around until it can be eased into the correct position. Sometimes, you need to use your fingers to support the dial surround so that it doesn't pop out of the case, and your other hand's fingers to flex the top of the finger plate fractionally. If you find this daunting and tricky to achieve, remove the finger plate, fit the case, then re-fit the finger plate. If you choose to do this, do NOT lever off the dial centre, but use a suction cup or even a bit of very sticky tape to pull it off. Then remove the single slotted screw under the label. Finally, after ensuring that none of the wires from the line cord/handset cord are trapped, tighten the screw at the back. Graham will probably have a more elegant, "official" method...

7th Apr 2023, 5:17 pm	#9
Oldcodger Nonode Join Date: Oct 2014 Location: West Midlands, UK. Posts: 2,152	Re: GPO 746 rotary dial sticks with the case on I found in my days on subs app fitting ( giving folks a phone to non GPO BLOKES) that it helped to use a small screwdriver ( No 1 to GPO blokes or small terminal to others) under the top part of dial ( 12 o'clock, looking at dial from front) to prise the cover over the dial. It helps if the screw at rear of base is held back before trying this. It can be daunting to those with only one phone, but is sometimes pays to be force full with 746. The dial ring on the phone is the cause of problems.