Capacitor polarity ID. - UK Vintage Radio Repair and Restoration Discussion Forum

vinrads · 31st May 2016, 9:31 am

Which is the pos the thin one or the thick one?

Cheers, Mick.

Nuvistor · 31st May 2016, 10:43 am

Without more info I would go for the thin one being positive.

Hopefully there are some markings on the body or the pins.

Frank

Station X · 31st May 2016, 10:54 am

I have a lot of these green capacitors and hadn't realised that they had no polarity markings.

Give me a couple of hours and I'll test one (hopefully not to destruction!) and let you know the result.

Lucien Nunes · 31st May 2016, 11:04 am

Is that a commercially-applied re-forming date label? What does it say and how does it compare to the manufacture date?

Perhaps there's continuity from neg tag to case?

Station X · 31st May 2016, 11:22 am

I have several of the caps which are made by Plessey. There are no polarity markings at all. The can isn't accessible for continuity testing as it's entirely covered in plastic.

turretslug · 31st May 2016, 11:28 am

Quote:

Originally Posted by Lucien Nunes

Is that a commercially-applied re-forming date label?

It has all the air of a military label, from the era of large, regular intake- possibly even National Service- and the need to occupy idle hands, the "whitewashing coal" syndrome! Would a commercial organisation really bother with re-forming, or would they just sling them out and buy new?

Station X · 31st May 2016, 11:52 am

Wide tag negative.
Narrow tag positive.

Final answer.

vinrads · 2nd Jun 2016, 11:11 am

Thank's for the info Graham, the reform date is June 1972. Mick.

turretslug · 2nd Jun 2016, 12:07 pm

It's a diversion from OP, but I'm still intrigued that it has undergone formal reformation as late as 1972 when electrolytics were no longer remotely exotic/expensive components. It seems difficult to believe that a commercial organisation would be able to justify any cost/benefit over discarding/replacement and it also seems difficult to believe that the military would countenance putting superannuated stock of such a relatively trivially priced component into, well, just about anything.

Reforming electrolytics is something I occasionally do when working on old stuff, but I'd classify it as recreational/curiosity more than anything else and only if it is a fairly key mechanical/appearance/presentation sort of thing. I'm not a profligate sort of person but if there's the slightest doubt about a capacitor or the chance of it ruining an expensive rectifier/transformer/whatever, it'll be swapped for a good quality modern component.

Just a tad intrigued!

G8HQP Dave · 2nd Jun 2016, 4:40 pm

Perhaps reforming avoided the paperwork required for replacing an old component with a slightly different modern component?

31st May 2016, 9:31 am	#1
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,762	Capacitor polarity ID. Which is the pos the thin one or the thick one? Cheers, Mick. Attached Thumbnails

31st May 2016, 10:43 am	#2
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Capacitor polarity ID. Without more info I would go for the thin one being positive. Hopefully there are some markings on the body or the pins. Frank

31st May 2016, 10:54 am	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Capacitor polarity ID. I have a lot of these green capacitors and hadn't realised that they had no polarity markings. Give me a couple of hours and I'll test one (hopefully not to destruction!) and let you know the result. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

31st May 2016, 11:04 am	#4
Lucien Nunes Rest in Peace Join Date: Apr 2008 Location: London, UK. Posts: 2,508	Re: Capacitor polarity ID. Is that a commercially-applied re-forming date label? What does it say and how does it compare to the manufacture date? Perhaps there's continuity from neg tag to case?

31st May 2016, 11:22 am	#5
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Capacitor polarity ID. I have several of the caps which are made by Plessey. There are no polarity markings at all. The can isn't accessible for continuity testing as it's entirely covered in plastic. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

31st May 2016, 11:52 am	#7
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Capacitor polarity ID. Wide tag negative. Narrow tag positive. Final answer. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

2nd Jun 2016, 11:11 am	#8
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,762	Re: Capacitor polarity ID. Thank's for the info Graham, the reform date is June 1972. Mick.

2nd Jun 2016, 12:07 pm	#9
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,396	Re: Capacitor polarity ID. It's a diversion from OP, but I'm still intrigued that it has undergone formal reformation as late as 1972 when electrolytics were no longer remotely exotic/expensive components. It seems difficult to believe that a commercial organisation would be able to justify any cost/benefit over discarding/replacement and it also seems difficult to believe that the military would countenance putting superannuated stock of such a relatively trivially priced component into, well, just about anything. Reforming electrolytics is something I occasionally do when working on old stuff, but I'd classify it as recreational/curiosity more than anything else and only if it is a fairly key mechanical/appearance/presentation sort of thing. I'm not a profligate sort of person but if there's the slightest doubt about a capacitor or the chance of it ruining an expensive rectifier/transformer/whatever, it'll be swapped for a good quality modern component. Just a tad intrigued!

2nd Jun 2016, 4:40 pm	#10
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Capacitor polarity ID. Perhaps reforming avoided the paperwork required for replacing an old component with a slightly different modern component?