Sony ICF-SW55 works on mains but not batteries - UK Vintage Radio Repair and Restoration Discussion Forum

Dougelec · 2nd Oct 2017, 10:59 am

My beloved Sony SW55 fails to power up on batteries but will run on mains if the batteries are removed. Can anyone suggest what could be causing this and perhaps a suitable repair. I've searched online for the symptoms but cannot find any mention of this particular fault. It's my receiver of choice when going into the wilds for some interference free DXing and I'm pretty knackered without it. Thanks in anticipation, Dougie.

Station X · 2nd Oct 2017, 12:10 pm

Circuit diagram here:-

http://www.radiomanual.info/schemi/R...F-SW55_sch.pdf

As far as I can see, the problem can only be with the power input jack or the diode between the battery and the regulators.

Quote:

but will run on mains if the batteries are removed.

So it won't run on mains if the batteries are present?

EDIT.

I don't know what your skill levels are or what test equipment you have available, but checking for 6 Volts from TP31 to TP29 and from TP31 to TP30 will soon tell you whether battery power is reaching the radio.

kevinaston1 · 2nd Oct 2017, 12:29 pm

Electrotanya has a full service manual for this.

D45 supplies B+ when an adaptor is in circuit. With no adaptor, B+ is supplied by D46. Either an OC diode, or cracked print.

Kevin

Dougelec · 2nd Oct 2017, 1:34 pm

Thanks very much for the suggestions and information, I really appreciate it. I'm an instrument technician/electrician by trade and know my way around a Fluke so I should be able to carry out the checks. I did open up the case this morning to check for anything obvious and only managed to remove the case, getting right inside looked a little daunting but I'll have a go. Cheers.

paulsherwin · 2nd Oct 2017, 1:41 pm

I know it's stating the obvious, but have you checked the battery compartment contacts carefully? If you have ever had a leaky battery in there, it may have caused damage that will cause a bad connection but is difficult to see. Also try a different set of batteries, as some cells develop a fault whereby they test OK on a meter but don't deliver any current.

If that's not it, then I agree with Kevin, though try a squirt of Servisol in the external power switch contacts.

2nd Oct 2017, 10:59 am	#1
Dougelec Retired Dormant Member Join Date: Jul 2016 Location: Washington, Tyne and Wear, UK. Posts: 2	Sony ICF-SW55 works on mains but not batteries My beloved Sony SW55 fails to power up on batteries but will run on mains if the batteries are removed. Can anyone suggest what could be causing this and perhaps a suitable repair. I've searched online for the symptoms but cannot find any mention of this particular fault. It's my receiver of choice when going into the wilds for some interference free DXing and I'm pretty knackered without it. Thanks in anticipation, Dougie.

2nd Oct 2017, 12:29 pm	#3
kevinaston1 Hexode Join Date: Aug 2014 Location: Featherstone, West Yorkshire, UK. Posts: 386	Re: Sony ICF-SW55 works on mains but not batteries Electrotanya has a full service manual for this. D45 supplies B+ when an adaptor is in circuit. With no adaptor, B+ is supplied by D46. Either an OC diode, or cracked print. Kevin

2nd Oct 2017, 1:34 pm	#4
Dougelec Retired Dormant Member Join Date: Jul 2016 Location: Washington, Tyne and Wear, UK. Posts: 2	Re: Sony ICF-SW55 works on mains but not batteries Thanks very much for the suggestions and information, I really appreciate it. I'm an instrument technician/electrician by trade and know my way around a Fluke so I should be able to carry out the checks. I did open up the case this morning to check for anything obvious and only managed to remove the case, getting right inside looked a little daunting but I'll have a go. Cheers.

2nd Oct 2017, 1:41 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,966	Re: Sony ICF-SW55 works on mains but not batteries I know it's stating the obvious, but have you checked the battery compartment contacts carefully? If you have ever had a leaky battery in there, it may have caused damage that will cause a bad connection but is difficult to see. Also try a different set of batteries, as some cells develop a fault whereby they test OK on a meter but don't deliver any current. If that's not it, then I agree with Kevin, though try a squirt of Servisol in the external power switch contacts.