R1155 transformer core stuck - UK Vintage Radio Repair and Restoration Discussion Forum

Ferguson 2000 · 8th May 2023, 10:25 pm

Hi,

Can anyone suggest a way to soften the locking compound used on this core adjuster which is Bakelite in a Bakelite surround.

I have tried switch cleaner, very thin oil, acetone and soaking in boiling water but it has not moved 0.01mm.

All suggestions gratefully received.

FrankB · 9th May 2023, 1:25 am

I had a problem decades ago with 2 variable transformers not adjusting. Turned out the lube they used on the Bakelite insulating rod swelled it up. I finally used a punch and light hammer to free it. Sanded it down to correct diameter and cleaned all the old lube off and used silicone grease for the lube.
I suspect this may be the case on your core, or the core was sealed in by an epoxy. If it's a "do or die" you might try a small pencil torch to heat it up. or the hammer & punch method. Risk is it could cause damage to the unit.
Loctite corp may make a solvent to remove thread lock and that might be worth a try also.

HamishBoxer · 9th May 2023, 8:03 am

Does it really need adjusting ?

Ferguson 2000 · 10th May 2023, 11:24 am

Hi to FrankB and HamishBoxer,

Thank you for your replies, I was hoping that someone had had this problem before and had found a suitable solvent, it would seem not.

I do need to adjust the core in order to balance the DF loop.

Best wishes, Geoffrey.

HamishBoxer · 10th May 2023, 11:51 am

Understood Geoffrey.

bill knox · 11th May 2023, 10:42 am

Hi

I have several R1155s, where is this capacitor located, I do not recognise it at all, but knowing how the AM wanted everything on these receivers locked tight they may have used Shellack (not sure if I have spelt that right) if so Methylated Spirits may work.

Let me know its location and I will look and see if I have one.

Regards

Bill

Station X · 11th May 2023, 1:11 pm

I don't think capacitors have been mentioned.

ms660 · 11th May 2023, 4:52 pm

Just for info for anyone that's interested, the DF Loop coils in the info I'm looking at in AP1186 Vol. 1 (Revised) are L4, L5 & L6, their top side chassis layout locations are Db, Da & Ca respectively.

Their trimmer capacitors are C57, C58 & C59 respectively, their bottom side chassis layout locations are Ah (C57 & C58) and Ag (C59)

Lawrence.

Ferguson 2000 · 22nd May 2023, 2:55 pm

Dear Bill, Graham and Lawrence,

Thank you for your replies.

It is one of the DF coil adjusters that is stuck solid - L4 but L5 is similar.

If I come up with a solution I will post it.

Best wishes, Geoffrey.

bill knox · 22nd May 2023, 11:33 pm

Hi My mistake where I got "capacitor" from I don't know.

Where in the r1155 is this part fitted, I have several r1155s and if possible I can remove it

Regards

Bill

8th May 2023, 10:25 pm	#1
Ferguson 2000 Tetrode Join Date: Jun 2008 Location: Stratford upon Avon, Warwickshire, UK. Posts: 80	R1155 transformer core stuck Hi, Can anyone suggest a way to soften the locking compound used on this core adjuster which is Bakelite in a Bakelite surround. I have tried switch cleaner, very thin oil, acetone and soaking in boiling water but it has not moved 0.01mm. All suggestions gratefully received. Attached Thumbnails __________________ Best wishes, Geoffrey.

9th May 2023, 1:25 am	#2
FrankB Heptode Join Date: Oct 2005 Location: Olympia, Washington, USA. Posts: 664	Re: R1155 transformer core stuck I had a problem decades ago with 2 variable transformers not adjusting. Turned out the lube they used on the Bakelite insulating rod swelled it up. I finally used a punch and light hammer to free it. Sanded it down to correct diameter and cleaned all the old lube off and used silicone grease for the lube. I suspect this may be the case on your core, or the core was sealed in by an epoxy. If it's a "do or die" you might try a small pencil torch to heat it up. or the hammer & punch method. Risk is it could cause damage to the unit. Loctite corp may make a solvent to remove thread lock and that might be worth a try also.

9th May 2023, 8:03 am	#3
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: R1155 transformer core stuck Does it really need adjusting ? __________________ G8JET BVWS Archivist and Member V.M.A.R.S

10th May 2023, 11:24 am	#4
Ferguson 2000 Tetrode Join Date: Jun 2008 Location: Stratford upon Avon, Warwickshire, UK. Posts: 80	Re: R1155 transformer core stuck Hi to FrankB and HamishBoxer, Thank you for your replies, I was hoping that someone had had this problem before and had found a suitable solvent, it would seem not. I do need to adjust the core in order to balance the DF loop. Best wishes, Geoffrey.

10th May 2023, 11:51 am	#5
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: R1155 transformer core stuck Understood Geoffrey. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

11th May 2023, 10:42 am	#6
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Re: R1155 transformer core stuck Hi I have several R1155s, where is this capacitor located, I do not recognise it at all, but knowing how the AM wanted everything on these receivers locked tight they may have used Shellack (not sure if I have spelt that right) if so Methylated Spirits may work. Let me know its location and I will look and see if I have one. Regards Bill

11th May 2023, 1:11 pm	#7
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: R1155 transformer core stuck I don't think capacitors have been mentioned. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th May 2023, 4:52 pm	#8
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: R1155 transformer core stuck Just for info for anyone that's interested, the DF Loop coils in the info I'm looking at in AP1186 Vol. 1 (Revised) are L4, L5 & L6, their top side chassis layout locations are Db, Da & Ca respectively. Their trimmer capacitors are C57, C58 & C59 respectively, their bottom side chassis layout locations are Ah (C57 & C58) and Ag (C59) Lawrence.

22nd May 2023, 2:55 pm	#9
Ferguson 2000 Tetrode Join Date: Jun 2008 Location: Stratford upon Avon, Warwickshire, UK. Posts: 80	Re: R1155 transformer core stuck Dear Bill, Graham and Lawrence, Thank you for your replies. It is one of the DF coil adjusters that is stuck solid - L4 but L5 is similar. If I come up with a solution I will post it. Best wishes, Geoffrey.

22nd May 2023, 11:33 pm	#10
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Re: R1155 transformer core stuck Hi My mistake where I got "capacitor" from I don't know. Where in the r1155 is this part fitted, I have several r1155s and if possible I can remove it Regards Bill