Whiskery AF117 - on the outside! - UK Vintage Radio Repair and Restoration Discussion Forum

sexton_mallard · 26th Jan 2016, 6:39 pm

I looked inside my Bush TR82B just now to check nothing unpleasant was going on with the rather old PP9 battery. Something caught my eye...sparkling. There on the case of a slightly corroded looking AF117 are...whiskers.

The other AF117s seem to have a smear of a greasy substance or no 'fuzziness'. Attached is a picture - a prominent whisker is on the right hand side. The picture does not do the metallic twinkling justice. I'd love to see inside if the same effect is happening...

mark pirate · 26th Jan 2016, 7:43 pm

Never seen that on the outside before, I bet the inside is fine

I have seen this happen on pot housings though, classic tin migration.
Oh yes, it does cause problems with pots. I opened up an intermittent pot that would not respond to Servisol, I was amazed at the amount of tin whiskers growing from the metal casing.

I cleaned it out thoroughly and painted the inside of the casing with some enamel paint. No problems with it since.

Mark

ionburn · 26th Jan 2016, 8:39 pm

I've not seen that for a while. It does remind me of a time when I picked up an old guitar I have and found that the knobs on the machine heads just fell apart. Maybe a similar problem although these were obviously very cheap.

Refugee · 26th Jan 2016, 9:15 pm

I found a huge amount of whiskers on the tuning dial frame in my low distortion sine wave generator.

ms660 · 26th Jan 2016, 9:24 pm

I've found them in some WW2 era comms receivers on soldered joints and cadmium? plated chassis.

Lawrence.

Refugee · 27th Jan 2016, 1:10 am

I have no idea what Marconi plated the chassis with but all the same it is clearly covered with whiskers on the tuner metalwork.

G4_Pete · 27th Jan 2016, 11:59 am

Zinc is another metal prone to this phenomena.
Pete

kalee20 · 27th Jan 2016, 1:39 pm

Are the whiskers on the Refugee's tuning dial, actual metal whiskers or just crystalline corrosion salts though?

Zinc does give rise to light fluffy corrosion - probably zinc hydroxide - but this is a different phenomenon to the tin whisker problem, where it is actual metal migration which is the problem.

26th Jan 2016, 6:39 pm	#1
sexton_mallard Heptode Join Date: Sep 2013 Location: Ellesmere, Shropshire, UK & Co. Cork, Ireland. Posts: 502	Whiskery AF117 - on the outside! I looked inside my Bush TR82B just now to check nothing unpleasant was going on with the rather old PP9 battery. Something caught my eye...sparkling. There on the case of a slightly corroded looking AF117 are...whiskers. The other AF117s seem to have a smear of a greasy substance or no 'fuzziness'. Attached is a picture - a prominent whisker is on the right hand side. The picture does not do the metallic twinkling justice. I'd love to see inside if the same effect is happening... Attached Thumbnails

26th Jan 2016, 7:43 pm	#2
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Re: Whiskery AF117 - on the outside! Never seen that on the outside before, I bet the inside is fine I have seen this happen on pot housings though, classic tin migration. Oh yes, it does cause problems with pots. I opened up an intermittent pot that would not respond to Servisol, I was amazed at the amount of tin whiskers growing from the metal casing. I cleaned it out thoroughly and painted the inside of the casing with some enamel paint. No problems with it since. Mark

26th Jan 2016, 8:39 pm	#3
ionburn Heptode Join Date: Dec 2014 Location: Lincoln, Lincolnshire, UK. Posts: 583	Re: Whiskery AF117 - on the outside! I've not seen that for a while. It does remind me of a time when I picked up an old guitar I have and found that the knobs on the machine heads just fell apart. Maybe a similar problem although these were obviously very cheap.

26th Jan 2016, 9:15 pm	#4
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Whiskery AF117 - on the outside! I found a huge amount of whiskers on the tuning dial frame in my low distortion sine wave generator. Attached Thumbnails

26th Jan 2016, 9:24 pm	#5
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Whiskery AF117 - on the outside! I've found them in some WW2 era comms receivers on soldered joints and cadmium? plated chassis. Lawrence.

27th Jan 2016, 1:10 am	#6
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: Whiskery AF117 - on the outside! I have no idea what Marconi plated the chassis with but all the same it is clearly covered with whiskers on the tuner metalwork.

27th Jan 2016, 11:59 am	#7
G4_Pete Hexode Join Date: Feb 2014 Location: Southampton, Hampshire, UK. Posts: 419	Re: Whiskery AF117 - on the outside! Zinc is another metal prone to this phenomena. Pete

27th Jan 2016, 1:39 pm	#8
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: Whiskery AF117 - on the outside! Are the whiskers on the Refugee's tuning dial, actual metal whiskers or just crystalline corrosion salts though? Zinc does give rise to light fluffy corrosion - probably zinc hydroxide - but this is a different phenomenon to the tin whisker problem, where it is actual metal migration which is the problem.