Tantalum Terrors. - UK Vintage Radio Repair and Restoration Discussion Forum

G6Tanuki · 24th Oct 2022, 4:52 pm

Today I had yet another of the little jelly bean Epoxy encapsulated Tantalum electrolytics do its firestarter act.

Lots of stinky smoke!!!!!

Not sure what voltage rating or colour it had been before the incident but afterwards it was a black stain on the PCB.

A nice new Panasonic radial lead one is now fitted.

We bewail the hopeless Waxies and the red/black Plessey electrolytics, but Tantalums are decades younger and no more reliable.

Bazz4CQJ · 24th Oct 2022, 5:03 pm

Yes quite so! Some time ago, I was given a scope, which needed attention.

It was quickly apparent that the power supply components had taken a beating. Further investigation found a tant in one of the pre-amps which had gone dead short. The scope had not been design for ease of service and it took a while to complete repairs, putting in a new tant. It lasted a few days.

It then got replaced with a good quality electrolytic and that worked perfectly well and is still in service 10 years later

.

B

paulsherwin · 24th Oct 2022, 5:40 pm

It's really a failed technology. I remember a great fuss about them when they started to appear because they were so small. They haven't stood the test of time though, and when they fail they *really* fail.

Bazz4CQJ · 24th Oct 2022, 6:07 pm

But here's a curious thing; I didn't replace all the tants in the scope (2 channels), I think I just replaced the two on the pre-amp of one channel.

The only other thing I did was to fit a small fan (ex PC) to improve ventilation, but that was more to try make things better for power supply, which had been having a tough time.

B

paulsherwin · 24th Oct 2022, 6:24 pm

Hmm.. once I'd made the effort to go inside I think I'd have whipped 'em all out. If one's gone bang there'll be another along before too long.

Bazz4CQJ · 24th Oct 2022, 6:46 pm

Quote:

Originally Posted by paulsherwin

Hmm.. once I'd made the effort to go inside I think I'd have whipped 'em all out. If one's gone bang there'll be another along before too long.

In hindsight, I tend to agree. But as said above, the following ten years have been problem-free.

Were one to go again, I'd have them all out. The risk of serious damage to the power supply components (probably unobtainium now) would clinch it.

B

G6Tanuki · 24th Oct 2022, 7:12 pm

While I would normally agree with the idea of replacing all the Tantalum jelly-beans while you are looking at the problem, in the case of my little AEL3030 l have the luxury of all the boards being easily-plug-in-and-unpluggable so if another Tantalum Terror decided to let go I can get to it in a few minutes.

Modular construction is great!!

joebog1 · 24th Oct 2022, 9:24 pm

I have a beautiful Interstate 20 Mhz log-linear sweep generator. It doesnt work. Why you might ask.
Its FULL of tag tants. I mean there must be 100 or so in there. Its also a pain to work on. I guess I have the time now, but its a daunting job.

Joe

Lloyd 1985 · 25th Oct 2022, 10:09 am

I’ve had trouble with the surface mounted ones, first was a 2009 MacBook Pro which went pop when I plugged it in to charge one night, gave me a fright as I’d heard about laptop batteries blowing up, and the sudden pop and sparks shooting out the side of the machine made me think it was that! Luckily there’s a fuse on the logic board which went open, a whole bunch of new caps and a new fuse bought the machine back to life. The other Was a HP 54600A scope, most of the 1uf SMD tants had burnt up, there was just ash left between the legs! They burnt the PCB too, which took some cleaning up. I have new caps, but I’ve yet to fit them, and surprisingly the scope works seemingly ok without them!

Regards
Lloyd

Maarten · 25th Oct 2022, 12:34 pm

Philips apparently knew early on that solid tants were not the way to go and developed solid aluminium capacitors as a feasible alternative. However a few years ago, Vishay/BC discontinued that range and I don't think they were ever available in SMD.

BTW, didn't LLJ word it wisely "beware of the blue tants"?

Jon_G4MDC · 26th Oct 2022, 9:42 pm

I am told Ericsson in Sweden banned their use quite early on.

G6Tanuki · 9th Nov 2022, 7:43 pm

And another one... ths time rather than self-immolating in a stinky cloud it chose to go short-circuit and so vaporize one of its connecting-leads.

A 25V-rated part working at 14.5V, surely it shouldn't have done this? I have yet to spring the rear screening-panels from the PCB to see if there are any copper tracks that have survived.

There are several small green 'jellybean' tants elsewhere in this equipment. I am minded to go on an all-out hit-mission and replace the lot with nice new low-ESR Pasnasonic or Rubycon electrolytics.

Cruisin Marine · 9th Nov 2022, 8:57 pm

They are the Devil's own work- they even failed early on back in the 70's/80's on Pye PMR gear.
I just change them whenever I see them, if they are not a problem right now, they will be sooner rather than later.

duncanlowe · 9th Nov 2022, 9:22 pm

I hate the things. First failure I saw was on a piece of equipment just weeks old while under test. The test was a bulk current injection test for immunity to RF, my colleague came out of the chamber followed by a nasty cloud of smoke. That was in the 80s.

Philips210 · 9th Nov 2022, 9:58 pm

I don't like working on live equipment with tantalum bead caps especially if used for supply filtering. I've seen the way they can give out their firework display and if one decides to blow while you have your head over the circuit board it could be quite nasty. They're probably OK if used in timing circuit applications with little risk of going s/c.

As suggested, a great alternative is solid aluminium capacitors if you can find them. They're very stable and reliable. I think they were marketed mainly by Philips and appear to have gone off the scene. It seems this is not due to the technology having any problems but rather the cost to produce them.
Another point was they were deemed to look too much like tantalums they were meant to replace so potential buyers may have been wary about purchasing them. The lead pitch is often wider than the tantalum bead types which doesn't help.

Regards,
Symon

Philips210 · 9th Nov 2022, 10:32 pm

OT but many years ago I saw a video where there was a problem with a certain make of monolithic ceramic capacitors. It showed them failing in a similar dramatic way as tantalum bead caps. Perhaps it was just a batch problem and a one off issue. I've found them to be reliable enough but wondered if anyone else has had any adverse experiences with them?

Regards,
Symon

24th Oct 2022, 4:52 pm	#1
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,010	Tantalum Terrors. Today I had yet another of the little jelly bean Epoxy encapsulated Tantalum electrolytics do its firestarter act. Lots of stinky smoke!!!!! Not sure what voltage rating or colour it had been before the incident but afterwards it was a black stain on the PCB. A nice new Panasonic radial lead one is now fitted. We bewail the hopeless Waxies and the red/black Plessey electrolytics, but Tantalums are decades younger and no more reliable. __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

24th Oct 2022, 5:03 pm	#2
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Tantalum Terrors. Yes quite so! Some time ago, I was given a scope, which needed attention. It was quickly apparent that the power supply components had taken a beating. Further investigation found a tant in one of the pre-amps which had gone dead short. The scope had not been design for ease of service and it took a while to complete repairs, putting in a new tant. It lasted a few days. It then got replaced with a good quality electrolytic and that worked perfectly well and is still in service 10 years later . B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

24th Oct 2022, 5:40 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,974	Re: Tantalum Terrors. It's really a failed technology. I remember a great fuss about them when they started to appear because they were so small. They haven't stood the test of time though, and when they fail they really fail.

24th Oct 2022, 6:07 pm	#4
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Tantalum Terrors. But here's a curious thing; I didn't replace all the tants in the scope (2 channels), I think I just replaced the two on the pre-amp of one channel. The only other thing I did was to fit a small fan (ex PC) to improve ventilation, but that was more to try make things better for power supply, which had been having a tough time. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

24th Oct 2022, 6:24 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,974	Re: Tantalum Terrors. Hmm.. once I'd made the effort to go inside I think I'd have whipped 'em all out. If one's gone bang there'll be another along before too long.

24th Oct 2022, 7:12 pm	#7
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,010	Re: Tantalum Terrors. While I would normally agree with the idea of replacing all the Tantalum jelly-beans while you are looking at the problem, in the case of my little AEL3030 l have the luxury of all the boards being easily-plug-in-and-unpluggable so if another Tantalum Terror decided to let go I can get to it in a few minutes. Modular construction is great!! __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

24th Oct 2022, 9:24 pm	#8
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	Re: Tantalum Terrors. I have a beautiful Interstate 20 Mhz log-linear sweep generator. It doesnt work. Why you might ask. Its FULL of tag tants. I mean there must be 100 or so in there. Its also a pain to work on. I guess I have the time now, but its a daunting job. Joe

25th Oct 2022, 10:09 am	#9
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,820	Re: Tantalum Terrors. I’ve had trouble with the surface mounted ones, first was a 2009 MacBook Pro which went pop when I plugged it in to charge one night, gave me a fright as I’d heard about laptop batteries blowing up, and the sudden pop and sparks shooting out the side of the machine made me think it was that! Luckily there’s a fuse on the logic board which went open, a whole bunch of new caps and a new fuse bought the machine back to life. The other Was a HP 54600A scope, most of the 1uf SMD tants had burnt up, there was just ash left between the legs! They burnt the PCB too, which took some cleaning up. I have new caps, but I’ve yet to fit them, and surprisingly the scope works seemingly ok without them! Regards Lloyd

25th Oct 2022, 12:34 pm	#10
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,204	Re: Tantalum Terrors. Philips apparently knew early on that solid tants were not the way to go and developed solid aluminium capacitors as a feasible alternative. However a few years ago, Vishay/BC discontinued that range and I don't think they were ever available in SMD. BTW, didn't LLJ word it wisely "beware of the blue tants"?

26th Oct 2022, 9:42 pm	#11
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Tantalum Terrors. I am told Ericsson in Sweden banned their use quite early on.

9th Nov 2022, 7:43 pm	#12
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,010	Re: Tantalum Terrors. And another one... ths time rather than self-immolating in a stinky cloud it chose to go short-circuit and so vaporize one of its connecting-leads. A 25V-rated part working at 14.5V, surely it shouldn't have done this? I have yet to spring the rear screening-panels from the PCB to see if there are any copper tracks that have survived. There are several small green 'jellybean' tants elsewhere in this equipment. I am minded to go on an all-out hit-mission and replace the lot with nice new low-ESR Pasnasonic or Rubycon electrolytics. Attached Thumbnails __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk. Last edited by G6Tanuki; 9th Nov 2022 at 8:08 pm.

9th Nov 2022, 8:57 pm	#13
Cruisin Marine Octode Join Date: Jul 2018 Location: Worthing, West Sussex, UK. Posts: 1,007	Re: Tantalum Terrors. They are the Devil's own work- they even failed early on back in the 70's/80's on Pye PMR gear. I just change them whenever I see them, if they are not a problem right now, they will be sooner rather than later. __________________ "Behind every crowd, there's a silver Moonshine"

9th Nov 2022, 9:22 pm	#14
duncanlowe Nonode Join Date: Jan 2016 Location: Stafford, Staffs. UK. Posts: 2,532	Re: Tantalum Terrors. I hate the things. First failure I saw was on a piece of equipment just weeks old while under test. The test was a bulk current injection test for immunity to RF, my colleague came out of the chamber followed by a nasty cloud of smoke. That was in the 80s.

9th Nov 2022, 9:58 pm	#15
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,580	Re: Tantalum Terrors. I don't like working on live equipment with tantalum bead caps especially if used for supply filtering. I've seen the way they can give out their firework display and if one decides to blow while you have your head over the circuit board it could be quite nasty. They're probably OK if used in timing circuit applications with little risk of going s/c. As suggested, a great alternative is solid aluminium capacitors if you can find them. They're very stable and reliable. I think they were marketed mainly by Philips and appear to have gone off the scene. It seems this is not due to the technology having any problems but rather the cost to produce them. Another point was they were deemed to look too much like tantalums they were meant to replace so potential buyers may have been wary about purchasing them. The lead pitch is often wider than the tantalum bead types which doesn't help. Regards, Symon

9th Nov 2022, 10:32 pm	#16
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,580	Re: Tantalum Terrors. OT but many years ago I saw a video where there was a problem with a certain make of monolithic ceramic capacitors. It showed them failing in a similar dramatic way as tantalum bead caps. Perhaps it was just a batch problem and a one off issue. I've found them to be reliable enough but wondered if anyone else has had any adverse experiences with them? Regards, Symon