Sony ICF-SW77 issues - UK Vintage Radio Repair and Restoration Discussion Forum

cerestan · 3rd Feb 2018, 2:02 pm

I made a recent purchase of a Sony ICF-2001D and ICF-SW77 from a charity shop. The 2001D works fine but the SW77 isn't so well.

On mains it sometimes initially appears working but soon locks up, or is just locked up to begin with. On battery it seems to be working fine.

In both cases the volume is super loud, even on minimum, raising the slider only makes it louder.

I know there are capacitor repair kits available, but I'm not sure the symptoms indicate this will fill fix the issues.

I did take a couple of pictures of the circuit board, although they probably aren't that helpful.

Any thoughts on what the cause might be and would it be worth getting repaired?

Many thanks.

Biggles · 4th Feb 2018, 12:23 am

Check that the supply voltage is correct to the pcb when operating on mains. Also that there are no short circuit rectifier diodes in the supply. It sounds like there is either too much ripple on the mains power supply (smoothing capacitor issues), or it is giving out the incorrect voltage to the set, as everything seems ok on a battery supply, which by it's nature is stable and ripple free. The volume problem could be caused by a bad connection to the earthy end of the volume pot, or maybe the pot is faulty, although on looking at the photos, the pot does seem to have more than the usual three connections, so may be a digital encoder. I am not familiar with this particular set but I think there may have been discussions on the forum about them before. May be worth a quick search.
Alan.

cerestan · 4th Feb 2018, 11:33 am

Thanks Alan,

Testing with an avo meter the psu is outputting 7v instead of 6v. That's about as much as my knowledge allows me to check.

I've a few universal power supplies but none of the connections will fit.

I think it's best I take to an electrician to take a look at it.

camtechman · 4th Feb 2018, 6:19 pm

Quote:

best I take to an electrician

Better an Electronics Engineer, not that Electricians aren't skilled in their field but their ability & knowledge to cope with the complexity of that used in your radio may not be sufficient.

cerestan · 4th Feb 2018, 6:54 pm

Good point. The guy I had in mind refers to himself as an Electronics Technician. Only used him once before but he seems to know his stuff.

Shall see how I get on.

camtechman · 5th Feb 2018, 2:09 pm

Good Luck.

felangga · 12th Jul 2018, 6:01 am

Do you have a plan to sell your SW77 or just the RF boards?

I have a broken SW77 with some missing parts I would like to salvage from other boards.

3rd Feb 2018, 2:02 pm	#1
cerestan Retired Dormant Member Join Date: Feb 2018 Location: Dover, Kent, UK. Posts: 3	Sony ICF-SW77 issues I made a recent purchase of a Sony ICF-2001D and ICF-SW77 from a charity shop. The 2001D works fine but the SW77 isn't so well. On mains it sometimes initially appears working but soon locks up, or is just locked up to begin with. On battery it seems to be working fine. In both cases the volume is super loud, even on minimum, raising the slider only makes it louder. I know there are capacitor repair kits available, but I'm not sure the symptoms indicate this will fill fix the issues. I did take a couple of pictures of the circuit board, although they probably aren't that helpful. Any thoughts on what the cause might be and would it be worth getting repaired? Many thanks. Attached Thumbnails

4th Feb 2018, 12:23 am	#2
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Sony ICF-SW77 issues Check that the supply voltage is correct to the pcb when operating on mains. Also that there are no short circuit rectifier diodes in the supply. It sounds like there is either too much ripple on the mains power supply (smoothing capacitor issues), or it is giving out the incorrect voltage to the set, as everything seems ok on a battery supply, which by it's nature is stable and ripple free. The volume problem could be caused by a bad connection to the earthy end of the volume pot, or maybe the pot is faulty, although on looking at the photos, the pot does seem to have more than the usual three connections, so may be a digital encoder. I am not familiar with this particular set but I think there may have been discussions on the forum about them before. May be worth a quick search. Alan. Last edited by Biggles; 4th Feb 2018 at 12:29 am.

4th Feb 2018, 11:33 am	#3
cerestan Retired Dormant Member Join Date: Feb 2018 Location: Dover, Kent, UK. Posts: 3	Re: Sony ICF-SW77 issues Thanks Alan, Testing with an avo meter the psu is outputting 7v instead of 6v. That's about as much as my knowledge allows me to check. I've a few universal power supplies but none of the connections will fit. I think it's best I take to an electrician to take a look at it.

4th Feb 2018, 6:54 pm	#5
cerestan Retired Dormant Member Join Date: Feb 2018 Location: Dover, Kent, UK. Posts: 3	Re: Sony ICF-SW77 issues Good point. The guy I had in mind refers to himself as an Electronics Technician. Only used him once before but he seems to know his stuff. Shall see how I get on.

5th Feb 2018, 2:09 pm	#6
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Sony ICF-SW77 issues Good Luck. __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

12th Jul 2018, 6:01 am	#7
felangga Retired Dormant Member Join Date: Jul 2018 Location: Yogyakarta, Indonesia. Posts: 1	Do you have a plan to sell your SW77 or just the RF boards? I have a broken SW77 with some missing parts I would like to salvage from other boards.