Reading on speaker IS & OS output transformer solder tags - UK Vintage Radio Repair and Restoration Discussion Forum

Luxman1050 · 5th Mar 2020, 7:06 pm

Hi all
can someone explain what this diagram means pic attached. Reading taken off the IS & OS speaker terminals on speaker output transformer.
Basic info most welcome.
Cheers

duncanlowe · 5th Mar 2020, 7:09 pm

The component analyser thinks its a mosfet.

Luxman1050 · 5th Mar 2020, 7:29 pm

Ah okay thanks.

Station X · 6th Mar 2020, 8:09 am

Test it using a meter on resistance range with the speaker disconnected.

IS = Inside Secondary? OS = Outside Secondary?

elanman99 · 6th Mar 2020, 10:00 am

What about

Input Start (of winding)

Output Start

Ian

Station X · 6th Mar 2020, 10:11 am

Your guess is as good as mine. The OP speaks of a speaker winding which to me implies secondary. A bit of ohmic testing will soon show what's what.

Model or part number would help.

Luxman1050 · 6th Mar 2020, 10:59 am

Its PYE Cambridge Output Transformer.
The ohms readings are 36 on speaker coil.
The ohms OS & IS is 3 and OP & IP is 136.
Not sure what numbers are for? Maybe number of turns in relation to impedance not sure. Excuse the wax not great job but needed to be done as old was falling off.
Pic attached of transformer.

Station X · 6th Mar 2020, 11:19 am

16.5:1 is probably the turns ratio. Impedance ratio will be the square of that. Lower than usual, but the speaker is 36R which is also higher than usual.

What's the actual fault?

Luxman1050 · 6th Mar 2020, 12:32 pm

There's no fault I was just curious as too the lettering and numbers and what exactly they meant. What I don't understand is why additional solder points which are not directly used to run the speaker are there. As both windings at either ends are not connected in any way or form through solder points, wiring or through the laminations. So I thought shed some light on numbers lettering and maybe that would give an indication of what they are all used for and if they do how they interact.

Luxman1050 · 6th Mar 2020, 12:39 pm

Forgot to say was also why my tester was giving me a mosfet inductance and capacitor readings of the transformer.

Luxman1050 · 6th Mar 2020, 12:48 pm

The penny dropped outer secondary & Inner secondary are 2.7ohms outer primary and inner primary 182ohms new coil reading 16.6 ohms.

Luxman1050 · 6th Mar 2020, 1:12 pm

So this is confusing the outer and inner go to speaker terminals as you would expect. But no capacitor across those terminals I would have thought possibly a 0.001uf there maybe. But the inner primary is connected to the metal speaker cone but the outer primary has no connection to any part of the speaker? Why?
I think there was another transformer on the speaker cone which those terminals connected to and that was also somehow connected to the magnet maybe to send 100v line to the magnet to charge it. Maybe it burnt out and was removed.

ms660 · 6th Mar 2020, 1:25 pm

It might have been capacitor fed.

Lawrence.

Luxman1050 · 6th Mar 2020, 2:11 pm

Yeah I think I'll run a cap across the secondary once it's all restored just waiting on some bolts. See what happens not sure why the inner primary was earthed on speaker when you have one on the transformer casing. Much shorter run which seems more appropriate.
The outer not sure on that one as it was connected somewhere as tab had reminants of wire soldered to it.
Plus the lower bobin has a single piece of copper wire soldered around it not connected to anything and the winding is tapped over so not sure what purpose that serves.

Luxman1050 · 6th Mar 2020, 2:14 pm

Theres pic of cooper wire on bottom bobbin.

elanman99 · 6th Mar 2020, 2:47 pm

Be good if you could clarify how many windings and connections this device has?

You mention 'inner primary' and that the 'outer and inner' go to speaker terminals.

I think we've established its not a mosfet, I thought it was a straight transformer with two windings but now I'm not sure.

Ian

ms660 · 6th Mar 2020, 3:15 pm

A bit of clarification:

https://www.vintage-radio.net/forum/...5&d=1573165801

https://www.vintage-radio.net/forum/...5&d=1557413223

https://www.vintage-radio.net/forum/...6&d=1557413223

The above from this thread:

https://www.vintage-radio.net/forum/....php?t=156415:

---------------------------------------------------------------------------------------

IP = Inner of Primary winding.
OP = Outer of Primary winding.

IS = Inner of Secondary winding.
OS = Outer of Secondary winding.

Lawrence.

Luxman1050 · 6th Mar 2020, 4:23 pm

I think the windings are the numbers either end of the solder tabs.
16:5:1 ratio
6:30 ratio
I'm assuming that's what they mean.
Like say I was getting 60pf readings, inductance reading and that mosfet reading plus general ohms readings.
Plus the windings seem to be in between the laminations on the primary side not the secondary as I was getting no continuity on secondary side.

Luxman1050 · 6th Mar 2020, 5:26 pm

If you look at pic attached you can see four threaded posts the other two are for the speaker terminals which could suggest an additional transformer was attached.
I think it's one of those not really sure what the numbers mean or how or if the magnet is or was charged from a 100v line. Not really discussed and if anyone can find an exact example be very helpful there is some resemblance to other speakers Majestic comes to mind but that's pure speculation.

Luxman1050 · 6th Mar 2020, 8:28 pm

That was interesting going over that thread as the general consensus seems to point towards a permanent magnet type. But there seems to be uncertainty aswell.
If the transformer has one winding it's a permanent magnet type? But this has two windings since removing the transformer which was not done before.
Now field coil laminations is another interesting point as again since stripping this down if this is correct on the front end of the magnet housing are 4 brass bolts and these are holding via 4 stainless steel pins copper laminations which sit on the front end and this is where the speaker surround connects too. I did not remove the large brass bolt on the rear as I was worried I'd do some damage. Now one of those brass bolts holding the copper laminations showed signs of overheating the other 3 being fine. Using one of the four studs as a ground point and connecting the other probe to the copper laminations I'm getting ohms readings. Should that be the case?
If I was to remove the main bolt I'm sure heat damage would be apparent. Do permanent magnet speakers get hot? and do they have copper laminations on the front end.
Field coil is that housed internally or externally? Or can it be either?
Can the humbucking coil be housed internally or does it need to be housed externally?
So going back to the transformer why is the inner primary earthed to chasis but there seems to be no idea where the outer primary should be wired too.
So at present there seems to be no definite idea as to what type it is.
Now if it was capacitor fed would that have been an electrolytic which would need to be rectified or some sort of power source otherwise it would not work is that right? Or would it have been non polarized capacitor. Either way would it need an external power source and what type of circuit would be used? I only ask as it was mentioned as a possibility.

5th Mar 2020, 7:06 pm	#1
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Reading on speaker IS & OS output transformer solder tags Hi all can someone explain what this diagram means pic attached. Reading taken off the IS & OS speaker terminals on speaker output transformer. Basic info most welcome. Cheers Attached Thumbnails

5th Mar 2020, 7:09 pm	#2
duncanlowe Nonode Join Date: Jan 2016 Location: Stafford, Staffs. UK. Posts: 2,532	Re: Reading on speaker IS & OS output transformer solder tags The component analyser thinks its a mosfet.

5th Mar 2020, 7:29 pm	#3
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags Ah okay thanks.

6th Mar 2020, 8:09 am	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Reading on speaker IS & OS output transformer solder tags Test it using a meter on resistance range with the speaker disconnected. IS = Inside Secondary? OS = Outside Secondary? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

6th Mar 2020, 10:00 am	#5
elanman99 Hexode Join Date: Oct 2010 Location: Sandiway, Cheshire, UK. Posts: 327	Re: Reading on speaker IS & OS output transformer solder tags What about Input Start (of winding) Output Start Ian

6th Mar 2020, 10:11 am	#6
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Reading on speaker IS & OS output transformer solder tags Your guess is as good as mine. The OP speaks of a speaker winding which to me implies secondary. A bit of ohmic testing will soon show what's what. Model or part number would help. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

6th Mar 2020, 10:59 am	#7
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags Its PYE Cambridge Output Transformer. The ohms readings are 36 on speaker coil. The ohms OS & IS is 3 and OP & IP is 136. Not sure what numbers are for? Maybe number of turns in relation to impedance not sure. Excuse the wax not great job but needed to be done as old was falling off. Pic attached of transformer. Attached Thumbnails

6th Mar 2020, 11:19 am	#8
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Reading on speaker IS & OS output transformer solder tags 16.5:1 is probably the turns ratio. Impedance ratio will be the square of that. Lower than usual, but the speaker is 36R which is also higher than usual. What's the actual fault? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

6th Mar 2020, 12:32 pm	#9
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags There's no fault I was just curious as too the lettering and numbers and what exactly they meant. What I don't understand is why additional solder points which are not directly used to run the speaker are there. As both windings at either ends are not connected in any way or form through solder points, wiring or through the laminations. So I thought shed some light on numbers lettering and maybe that would give an indication of what they are all used for and if they do how they interact.

6th Mar 2020, 12:39 pm	#10
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags Forgot to say was also why my tester was giving me a mosfet inductance and capacitor readings of the transformer.

6th Mar 2020, 12:48 pm	#11
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags The penny dropped outer secondary & Inner secondary are 2.7ohms outer primary and inner primary 182ohms new coil reading 16.6 ohms.

6th Mar 2020, 1:12 pm	#12
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags So this is confusing the outer and inner go to speaker terminals as you would expect. But no capacitor across those terminals I would have thought possibly a 0.001uf there maybe. But the inner primary is connected to the metal speaker cone but the outer primary has no connection to any part of the speaker? Why? I think there was another transformer on the speaker cone which those terminals connected to and that was also somehow connected to the magnet maybe to send 100v line to the magnet to charge it. Maybe it burnt out and was removed.

6th Mar 2020, 1:25 pm	#13
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Reading on speaker IS & OS output transformer solder tags It might have been capacitor fed. Lawrence.

6th Mar 2020, 2:11 pm	#14
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags Yeah I think I'll run a cap across the secondary once it's all restored just waiting on some bolts. See what happens not sure why the inner primary was earthed on speaker when you have one on the transformer casing. Much shorter run which seems more appropriate. The outer not sure on that one as it was connected somewhere as tab had reminants of wire soldered to it. Plus the lower bobin has a single piece of copper wire soldered around it not connected to anything and the winding is tapped over so not sure what purpose that serves.

6th Mar 2020, 2:14 pm	#15
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags Theres pic of cooper wire on bottom bobbin. Attached Thumbnails

6th Mar 2020, 2:47 pm	#16
elanman99 Hexode Join Date: Oct 2010 Location: Sandiway, Cheshire, UK. Posts: 327	Re: Reading on speaker IS & OS output transformer solder tags Be good if you could clarify how many windings and connections this device has? You mention 'inner primary' and that the 'outer and inner' go to speaker terminals. I think we've established its not a mosfet, I thought it was a straight transformer with two windings but now I'm not sure. Ian

6th Mar 2020, 3:15 pm	#17
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Reading on speaker IS & OS output transformer solder tags A bit of clarification: https://www.vintage-radio.net/forum/...5&d=1573165801 https://www.vintage-radio.net/forum/...5&d=1557413223 https://www.vintage-radio.net/forum/...6&d=1557413223 The above from this thread: https://www.vintage-radio.net/forum/....php?t=156415: --------------------------------------------------------------------------------------- IP = Inner of Primary winding. OP = Outer of Primary winding. IS = Inner of Secondary winding. OS = Outer of Secondary winding. Lawrence.

6th Mar 2020, 4:23 pm	#18
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags I think the windings are the numbers either end of the solder tabs. 16:5:1 ratio 6:30 ratio I'm assuming that's what they mean. Like say I was getting 60pf readings, inductance reading and that mosfet reading plus general ohms readings. Plus the windings seem to be in between the laminations on the primary side not the secondary as I was getting no continuity on secondary side.

6th Mar 2020, 5:26 pm	#19
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags If you look at pic attached you can see four threaded posts the other two are for the speaker terminals which could suggest an additional transformer was attached. I think it's one of those not really sure what the numbers mean or how or if the magnet is or was charged from a 100v line. Not really discussed and if anyone can find an exact example be very helpful there is some resemblance to other speakers Majestic comes to mind but that's pure speculation. Attached Thumbnails

6th Mar 2020, 8:28 pm	#20
Luxman1050 Octode Join Date: Apr 2019 Location: Margate, Kent, UK. Posts: 1,728	Re: Reading on speaker IS & OS output transformer solder tags That was interesting going over that thread as the general consensus seems to point towards a permanent magnet type. But there seems to be uncertainty aswell. If the transformer has one winding it's a permanent magnet type? But this has two windings since removing the transformer which was not done before. Now field coil laminations is another interesting point as again since stripping this down if this is correct on the front end of the magnet housing are 4 brass bolts and these are holding via 4 stainless steel pins copper laminations which sit on the front end and this is where the speaker surround connects too. I did not remove the large brass bolt on the rear as I was worried I'd do some damage. Now one of those brass bolts holding the copper laminations showed signs of overheating the other 3 being fine. Using one of the four studs as a ground point and connecting the other probe to the copper laminations I'm getting ohms readings. Should that be the case? If I was to remove the main bolt I'm sure heat damage would be apparent. Do permanent magnet speakers get hot? and do they have copper laminations on the front end. Field coil is that housed internally or externally? Or can it be either? Can the humbucking coil be housed internally or does it need to be housed externally? So going back to the transformer why is the inner primary earthed to chasis but there seems to be no idea where the outer primary should be wired too. So at present there seems to be no definite idea as to what type it is. Now if it was capacitor fed would that have been an electrolytic which would need to be rectified or some sort of power source otherwise it would not work is that right? Or would it have been non polarized capacitor. Either way would it need an external power source and what type of circuit would be used? I only ask as it was mentioned as a possibility.