Sony ICF-SW1 - not usual fault? - UK Vintage Radio Repair and Restoration Discussion Forum

stormcat · 24th Oct 2008, 1:49 pm

It worked for a week, then the all the AM bands went very quiet and distorted (I was listening to it and heard it go). FM works fine.

I replaced all the SM electrolytics, removed someone's previous bodge atthe "motorboating" caps,but the very quiet and distorted AM problem remains.

Does anyone have an idea of what to look at next, please?

sabaman · 24th Oct 2008, 4:38 pm

Hi Stormcat,

If you havn't done so already you may want to check the 'through-board' connections that connect track on one side of the board to the other - a multimeter on continuity (producing a beep) is a reasonably quick way to determine if they are ok, but the probes may need to be sharp to cut through any protective varnish (or probably more likely the electrolyte that leaks from the caps). Sometimes (quite a lot of the time) the through connectors will go high resistance. Obviously check around where the leaky caps originally were. These connectors can also be under surface mount components too don't forget! Check for corroded track too - sometimes the leakage eats through. Good luck - this type of leakage causes all sorts of problems which can be a real pain to find - I speak from experience.

Regards,
Seth.

stormcat · 24th Oct 2008, 8:53 pm

Thank you, Seth.

Sounds good advice.

I looked at one through-hole, near to where I soldered, and it seemed OK.
But I will certainly go back in and check them out properly (there was only a small leak there).

How would I repair one? Tiny strand of tinned copper wire inside and soldered each end?

sabaman · 25th Oct 2008, 9:57 am

Hi,

Yes, my normal method of repair is as follows : (You have to be very careful though; a steady hand is needed - if you're not confident I wouldn't risk doing this as you may create more problems than when you started!).

Make sure you have clear access to the suspect through board connector (no components in the way or over the top of the hole). Drill a tiny hole through the centre of the connector; just large enough for a tiny strand of wire to fit through. One of those 'Dremmel' or hobby drills should be suitable for the purpose. Gently remove any protective varnish from the track/connector area so you can solder the cable each side of the connector. Thread wire through hole. Solder wire. Cut the wire as close to the pcb as possible. I find folding the bit of wire over the through hole once threaded keeps it in place while soldering. Can be tricky, but it does the job. Good luck!

Regards,
Seth.

stormcat · 27th Oct 2008, 7:26 pm

There seems to be an environmental effect on the fault... This SW1 failed in the kitchen (damp) and has mostly recovered after a day in the workshop (dry). I tried this out again and the same result... so it's drying in the airing-cupboard at the moment.

No idea what could be being affected, but I'll have a good look and clean round. Maybe some capacitor-juice is still there and absorbing moisture from the atmosphere.

-

Have got a SW7600 open at the moment - absolutely soaked with electrolyte!

Thanks again for your input, Seth.

Nigel

stormcat · 14th Nov 2008, 7:05 pm

Weirdly... the now 24-capacitor-replaced 7600 is showing the same symptoms: slowly failing in the damp kitchen, coming back after being in the airing cupboard - both over a few days.

I've obviously left something hygroscopic on the boards.

My other SW1 is fine in the kitchen - it has had two caps replaced, but did not suffer from any electrolyte leakage.

24th Oct 2008, 1:49 pm	#1
stormcat Retired Dormant Member Join Date: Oct 2008 Location: Calstock, Cornwall Posts: 8	Sony ICF-SW1 - not usual fault? It worked for a week, then the all the AM bands went very quiet and distorted (I was listening to it and heard it go). FM works fine. I replaced all the SM electrolytics, removed someone's previous bodge atthe "motorboating" caps,but the very quiet and distorted AM problem remains. Does anyone have an idea of what to look at next, please? Last edited by Station X; 24th Oct 2008 at 3:03 pm. Reason: TO COMPLY WITH FORUM RULES.

24th Oct 2008, 4:38 pm	#2
sabaman Pentode Join Date: Mar 2005 Location: Portsmouth, Hampshire, UK. Posts: 116	Re: Sony ICF-SW1 - not usual fault? Hi Stormcat, If you havn't done so already you may want to check the 'through-board' connections that connect track on one side of the board to the other - a multimeter on continuity (producing a beep) is a reasonably quick way to determine if they are ok, but the probes may need to be sharp to cut through any protective varnish (or probably more likely the electrolyte that leaks from the caps). Sometimes (quite a lot of the time) the through connectors will go high resistance. Obviously check around where the leaky caps originally were. These connectors can also be under surface mount components too don't forget! Check for corroded track too - sometimes the leakage eats through. Good luck - this type of leakage causes all sorts of problems which can be a real pain to find - I speak from experience. Regards, Seth. Last edited by sabaman; 24th Oct 2008 at 4:40 pm. Reason: Forgot something!

24th Oct 2008, 8:53 pm	#3
stormcat Retired Dormant Member Join Date: Oct 2008 Location: Calstock, Cornwall Posts: 8	Re: Sony ICF-SW1 - not usual fault? Thank you, Seth. Sounds good advice. I looked at one through-hole, near to where I soldered, and it seemed OK. But I will certainly go back in and check them out properly (there was only a small leak there). How would I repair one? Tiny strand of tinned copper wire inside and soldered each end?

25th Oct 2008, 9:57 am	#4
sabaman Pentode Join Date: Mar 2005 Location: Portsmouth, Hampshire, UK. Posts: 116	Re: Sony ICF-SW1 - not usual fault? Hi, Yes, my normal method of repair is as follows : (You have to be very careful though; a steady hand is needed - if you're not confident I wouldn't risk doing this as you may create more problems than when you started!). Make sure you have clear access to the suspect through board connector (no components in the way or over the top of the hole). Drill a tiny hole through the centre of the connector; just large enough for a tiny strand of wire to fit through. One of those 'Dremmel' or hobby drills should be suitable for the purpose. Gently remove any protective varnish from the track/connector area so you can solder the cable each side of the connector. Thread wire through hole. Solder wire. Cut the wire as close to the pcb as possible. I find folding the bit of wire over the through hole once threaded keeps it in place while soldering. Can be tricky, but it does the job. Good luck! Regards, Seth.

27th Oct 2008, 7:26 pm	#5
stormcat Retired Dormant Member Join Date: Oct 2008 Location: Calstock, Cornwall Posts: 8	Re: Sony ICF-SW1 - not usual fault? There seems to be an environmental effect on the fault... This SW1 failed in the kitchen (damp) and has mostly recovered after a day in the workshop (dry). I tried this out again and the same result... so it's drying in the airing-cupboard at the moment. No idea what could be being affected, but I'll have a good look and clean round. Maybe some capacitor-juice is still there and absorbing moisture from the atmosphere. - Have got a SW7600 open at the moment - absolutely soaked with electrolyte! Thanks again for your input, Seth. Nigel

14th Nov 2008, 7:05 pm	#6
stormcat Retired Dormant Member Join Date: Oct 2008 Location: Calstock, Cornwall Posts: 8	Re: Sony ICF-SW1 - not usual fault? Weirdly... the now 24-capacitor-replaced 7600 is showing the same symptoms: slowly failing in the damp kitchen, coming back after being in the airing cupboard - both over a few days. I've obviously left something hygroscopic on the boards. My other SW1 is fine in the kitchen - it has had two caps replaced, but did not suffer from any electrolyte leakage.