Sony ICF 880L transformer replacement - UK Vintage Radio Repair and Restoration Discussion Forum

ManxDave · 25th Sep 2018, 11:05 pm

This may not be vintage ( early 1990s ? ) but I could do with some help choosing a replacement mains transformer, original primary is open circuit.
Original is marked 1-450-325-11 TAM M9403 but extensive searching finds no data.
It is a mains/battery transistor radio, battery supply is 6V and the mains input is labelled as 4W. Is it just as simple as a 6-0-6V output?
I can upload a snip of the PSU section of a schematic obtained elsewhere if this is allowed?

Herald1360 · 25th Sep 2018, 11:26 pm

A snip is fine even if it's "up top", if it isn't, the whole lot is OK.

Is the dc supply in the set regulated or unregulated? 6-0-6 will give a slightly higher than 7v dc unregulated supply, but a suitable series diode or two on the dc output could fix that. For a regulated supply slightly more, maybe 8-0-8 would be needed for suitable headroom for the regulator.

ManxDave · 26th Sep 2018, 9:33 am

Hopefully a readable snip of the power section attached

GRID LEAK · 26th Sep 2018, 11:08 am

As Herald1360 says, a 6-0-6v tx will give a rectified voltage around 7v, but a fresh set of batteries would be around that voltage too. So I would be happy to use a 6-0-6v tx. If you're worried go for a 5-0-5v tx instead.
Regards
John.

ManxDave · 26th Sep 2018, 2:23 pm

Thanks to you both. A 6-0-6 will be fitted, Dave

MotorBikeLes · 26th Sep 2018, 9:53 pm

There is every chance that the transformer will have a built in thermal fuse, sometimes easy to see, sometimes less so. A clue often is an "extra" tag on the trannie if it is a tagged one. You can then identify an O/C fuse AND a good primary. These often fail for no good reason. Back in the day, the likes of Philips and Grundig used replaceable ones, so easy to deal with. You MAY consider bypassing the existing fuse with a suitable replacement and thermally tying it to the transormer's surface.
Les.

ManxDave · 26th Sep 2018, 10:18 pm

Thanks Les
One to remember for the future but I have discovered this transformer has physical damage. I suspect the radio has been dropped at some stage. On desoldering the transformer one of the primary pins and the plastic it was mounted in fell off due to a pre-existing crack. There was also a large chunk out of one of the 1N4002 diodes but surprisingly it is still working. No obvious other damage and the radio works with batteries so hopefully a replacement transformer will sort it. Thanks Dave

25th Sep 2018, 11:05 pm	#1
ManxDave Tetrode Join Date: Nov 2014 Location: Isle of Man Posts: 86	Sony ICF 880L transformer replacement This may not be vintage ( early 1990s ? ) but I could do with some help choosing a replacement mains transformer, original primary is open circuit. Original is marked 1-450-325-11 TAM M9403 but extensive searching finds no data. It is a mains/battery transistor radio, battery supply is 6V and the mains input is labelled as 4W. Is it just as simple as a 6-0-6V output? I can upload a snip of the PSU section of a schematic obtained elsewhere if this is allowed?

25th Sep 2018, 11:26 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Sony ICF 880L transformer replacement A snip is fine even if it's "up top", if it isn't, the whole lot is OK. Is the dc supply in the set regulated or unregulated? 6-0-6 will give a slightly higher than 7v dc unregulated supply, but a suitable series diode or two on the dc output could fix that. For a regulated supply slightly more, maybe 8-0-8 would be needed for suitable headroom for the regulator. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

26th Sep 2018, 9:33 am	#3
ManxDave Tetrode Join Date: Nov 2014 Location: Isle of Man Posts: 86	Re: Sony ICF 880L transformer replacement Hopefully a readable snip of the power section attached Attached Thumbnails

26th Sep 2018, 11:08 am	#4
GRID LEAK Triode Join Date: Jun 2009 Location: Lancashire, UK. Posts: 46	Re: Sony ICF 880L transformer replacement As Herald1360 says, a 6-0-6v tx will give a rectified voltage around 7v, but a fresh set of batteries would be around that voltage too. So I would be happy to use a 6-0-6v tx. If you're worried go for a 5-0-5v tx instead. Regards John.

26th Sep 2018, 2:23 pm	#5
ManxDave Tetrode Join Date: Nov 2014 Location: Isle of Man Posts: 86	Re: Sony ICF 880L transformer replacement Thanks to you both. A 6-0-6 will be fitted, Dave

26th Sep 2018, 9:53 pm	#6
MotorBikeLes Nonode Join Date: Dec 2012 Location: Kirk Michael, Isle of Man Posts: 2,350	Re: Sony ICF 880L transformer replacement There is every chance that the transformer will have a built in thermal fuse, sometimes easy to see, sometimes less so. A clue often is an "extra" tag on the trannie if it is a tagged one. You can then identify an O/C fuse AND a good primary. These often fail for no good reason. Back in the day, the likes of Philips and Grundig used replaceable ones, so easy to deal with. You MAY consider bypassing the existing fuse with a suitable replacement and thermally tying it to the transormer's surface. Les.

26th Sep 2018, 10:18 pm	#7
ManxDave Tetrode Join Date: Nov 2014 Location: Isle of Man Posts: 86	Re: Sony ICF 880L transformer replacement Thanks Les One to remember for the future but I have discovered this transformer has physical damage. I suspect the radio has been dropped at some stage. On desoldering the transformer one of the primary pins and the plastic it was mounted in fell off due to a pre-existing crack. There was also a large chunk out of one of the 1N4002 diodes but surprisingly it is still working. No obvious other damage and the radio works with batteries so hopefully a replacement transformer will sort it. Thanks Dave