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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 19th Jun 2019, 4:05 pm   #21
emeritus
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Default Re: Poor solderability of old components, solutions?

If it's ring pull, then it's pretty certain to be Aluminium. I haven't seen a steel sardine tin for years.
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Old 19th Jun 2019, 5:19 pm   #22
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Default Re: Poor solderability of old components, solutions?

Quote:
Originally Posted by MotorBikeLes View Post
A plan I adopted decades ago when soldering "new old stock" was to scrape every leg ON FOUR sides with the BACK of a small size "snap a piece off" craft knife.
Not sure why I adopted that method, but it DOES work.
Old metal oxide resistors that have got hot (scope deflection outputs) always got the "four scrapes treatment" with good results.
Les.
My vote is for "Your Method"!
Some of the newer components seem to have tinned steel leads, as they are attracted by a magnet.
Dave,
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Old 19th Jun 2019, 5:20 pm   #23
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Default Re: Poor solderability of old components, solutions?

Thanks for all the input. I had tried a quick scrape but it didn't seem to help. I have a fibreglass pencil somewhere so that's definately a try. I also have alloy wheel cleaner and descaler so other options.

I'm sure the terminals are meant to be soldered using ordinary solder, in fact I've used the very same parts before, just not from this batch of parts that I bought. The last batch came from RS as they were selling off their stock since the part was discontinued.

I'll try the pencil first when I find it and report back here.
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Old 19th Jun 2019, 8:39 pm   #24
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Default Re: Poor solderability of old components, solutions?

Tin cans seem to be coated in a varnish to reduce corrosion from the contents.
I used to use the base of Ovaltine drums which would solder very easily. Unfortunately they now use plastic containers.
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Old 19th Jun 2019, 8:51 pm   #25
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Default Re: Poor solderability of old components, solutions?

So apart from the fact the old insert in my fibreglass pencil was breaking up so I got the bits in my fingers, the replacement is fine and worked nicely on one of the components. That and some flux from a pen. Still needed a couple of seconds for the flux to work and solder to take, but all legs now llok well tinned. Unfortunately I have none of the bare boards these are for, so need some more to confirm 100% that its worked but it seems great, thanks all.
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Old 19th Jun 2019, 9:27 pm   #26
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Default Re: Poor solderability of old components, solutions?

Just a word of warning re: optocouplers as per the O/P, they can be damaged by either excess and/or prolonged heat, the following extract was taken from a technical bulletin issued by Sharp wrt the PSU repair on a few of their CTV chassis.

Quote:
The opto coupler is easily damaged by excessive heat while soldering, so remember to keep your
soldering iron temperature turned down to 250oC or below, and not to solder for more than 10 seconds
on each leg. If these conditions are not met the transparent barrier between the LED and opto
transistor will be damaged. Note that sometimes the set will work for several weeks or months before
failing if the opto has been damaged during fitting
Shades of old Germanium devices
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Old 19th Jun 2019, 10:43 pm   #27
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Default Re: Poor solderability of old components, solutions?

Hi.

Like others, I've always used a small craft knife to clean tarnished component leads and found this to work generally well. I have also successfully used a fibre glass pen but don't like using it due to the annoying fibres that stick in your skin.
Many mains droppers (large ballast resistors) often show signs of rust on their tags and can be difficult to solder. After scraping clean the tags, I've found high melting point solder to work very well. It gives good adhesion to the tag probably due to silver content within the solder.

Regards,
Symon
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Old 20th Jun 2019, 1:17 am   #28
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Default Re: Poor solderability of old components, solutions?

Quote:
Originally Posted by Red to black View Post
Quote:
The opto coupler is easily damaged by excessive heat while soldering, so remember to keep your
soldering iron temperature turned down to 250oC or below, and not to solder for more than 10 seconds
on each leg. If these conditions are not met the transparent barrier between the LED and opto
transistor will be damaged. Note that sometimes the set will work for several weeks or months before
failing if the opto has been damaged during fitting
Shades of old Germanium devices
Ten seconds per pin? I'm not surprised Sharp were seeing failures with that advice.

By the way, one sure way of destroying an LED is to solder it while it is illuminated, but don't ask how I know that.
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Old 20th Jun 2019, 5:52 am   #29
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Default Re: Poor solderability of old components, solutions?

Hi Graham,
Sharp also issued a later tech. bulletin which simply stated the opto should be soldered as quickly as possible for the above reasons, the extract above was simply the first instance I came across when I looked through my archives to quote in a post.
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Old 20th Jun 2019, 7:41 am   #30
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Default Re: Poor solderability of old components, solutions?

Quote:
Originally Posted by Andrew2 View Post
Just slightly off-topic: Any idea what material is used for the flat tins that contain kippers, sardines in oil etc? A while ago I decided to cut one up to use as screening for a homebrew project and then discovered it would not take solder no matter how much I cleaned or fluxed it.
You can buy brand new 2oz tobacco tins, no labels, on ebay. They are tinplated steel and solder well.

Peter
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Old 20th Jun 2019, 9:09 am   #31
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Default Re: Poor solderability of old components, solutions?

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Originally Posted by G6Tanuki View Post
A lot of the fish-cans these days are aluminium.

Check with a magnet to see if it's plated-steel or something else. [I can confirm that 'Branston' baked-bean cans are solderable, plated steel, having today used a slice of one to make-up a grounding strap for the outer-braid of some thick coax]
Ah, they're aluminium! Odd, as they don't seem like it at all, feeling more like a thin tin plate. The peel-off lid is quite springy, not like ali at all.
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Old 20th Jun 2019, 9:30 am   #32
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Default Re: Poor solderability of old components, solutions?

I've got two tins of sardines in the food cupboard, both well in date, and have just tested them with a magnet. One is steel and the other is not.

Alan
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Old 20th Jun 2019, 7:49 pm   #33
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Default Re: Poor solderability of old components, solutions?

To get leads clean I use a green nylon scrubbing pad, just clamp it round the lead and drag it through twice. Cheap and very effective.

I use an off cut of fibreglass net rod rather than a fibreglass pen, about as effective but you don't get the sharp fibres and it will last a very long time
Mick
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Old 20th Jun 2019, 8:10 pm   #34
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Default Re: Poor solderability of old components, solutions?

I use a fibre glass pen for anything that looks too iffy, but these days I also often use liquid flux as well as standard 60 40 cored solder as I find the flux (the type used with sm components) seems to improve things no end.
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Old 20th Jun 2019, 9:06 pm   #35
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Default Re: Poor solderability of old components, solutions?

Quote:
Originally Posted by Andrew2 View Post
Ah, they're aluminium! Odd, as they don't seem like it at all, feeling more like a thin tin plate. The peel-off lid is quite springy, not like ali at all.
You rarely come across pure aluminium, it's almost always in the form of some alloy or another and some can exhibit a feeling of hardness that seems like tin plated steel. It can be difficult to assess the density as well of some shapes, so magnets are the best arbiter.

David
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