Author Topic: Replacement tantalum: are they colour-coded?  (Read 985 times)

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Offline cprobertson1

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Replacement tantalum: are they colour-coded?
« on: February 25, 2018, 01:23:17 am »
Happy Saturday folks!

Just started repair of my wavetech signal generator - and after taking Gandalf's advice (when in doubt, follow your nose) I think I've found the culprit! A blown tantalum... at least I think it's a tantalum...? Are there any similarly shaped capacitors that aren't tantalums?

The aroma of magic smoke is magnificent! The lab will be well-perfumed for days to come!


The capacitor is turquoise in colour - and is marked +22 / +16V - so assumed 22 microfarad - but given that this is part of the RF amplifier module - I'm concerned about getting the wrong replacement - is the colour indicative of anything in particular or can I shove any 22uF / 16V tantalum in there?
 

Offline paschulke2

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Re: Replacement tantalum: are they colour-coded?
« Reply #1 on: February 25, 2018, 01:34:54 am »
[…] is the colour indicative of anything in particular or can I shove any 22uF / 16V tantalum in there?

No. Yes. (And: yes, it's a tantalum capacitor.)

If the DC voltage on this capacitor was close to 16V I would replace it with a 22µF/25V tantalum capacitor.
 

Offline SeanB

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Re: Replacement tantalum: are they colour-coded?
« Reply #2 on: February 25, 2018, 03:00:18 am »
It was light blue, went gren and black as it failed. The replacement can be almost any 22uF 16 or 25V  tantalum bead capacitor, the colour generally is irrelevant, it just shows in many cases the manufacturer very broadly, as there generally are a good number making the blue ones.
 

Offline anachrocomputer

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Re: Replacement tantalum: are they colour-coded?
« Reply #3 on: February 25, 2018, 10:39:20 am »
Some older tantalum capacitors do have coloured bands and spots on them, which mean something. But this one does not. Just about any replacement tantalum capacitor with the same capacitance and the same or higher voltage rating will be fine.
 
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Offline Inverted18650

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Re: Replacement tantalum: are they colour-coded?
« Reply #4 on: February 25, 2018, 11:19:41 am »
Keep that one for a piece of wall art.

Offline mr.fabe

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Re: Replacement tantalum: are they colour-coded?
« Reply #5 on: February 26, 2018, 02:44:28 am »
Some older tantalum capacitors do have coloured bands and spots on them, which mean something.

Something like this..


and the decoder chart..



« Last Edit: February 26, 2018, 02:56:46 am by mr.fabe »
 
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Offline cprobertson1

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Re: Replacement tantalum: are they colour-coded?
« Reply #6 on: February 26, 2018, 05:34:05 pm »
Keep that one for a piece of wall art.

You know... I reckon individual failed components encased in acrylic would make quite a nice looking desk-ornament ;) One of my older pieces of kit has a "self-destructed" 4000mF (wait... that's just 4F :O) capacitor in it - and being from the early 90's it's a HUGE capacitor - no small form-factor super-caps here! Well... half of it is gone - it's sort of spread itself across the rest of the board (causing a HUGE number of problems... there are fibres EVERYWHERE!) - but what's left would look very good in resin... I think I'd need to place it under vacuum though - as the fibres/foil will trap a lot of bubbles were I just to submerge it acrylic...

Some older tantalum capacitors do have coloured bands and spots on them, which mean something.
and the decoder chart..


Straight to my reference folder ;)
 

Offline mahi

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Re: Replacement tantalum: are they colour-coded?
« Reply #7 on: February 26, 2018, 05:41:35 pm »
I don't mean to hijack the thread but since the discussion is about tantalum capacitor markings and color codes... Does anyone know the voltage rating of the 2µ2 tantalum capacitor in the attached picture? The markings on the capacitor are:

2.2
20b


The 20b could be 206 but the font style really suggests the last character is a b.

Judging by the color coding chart posted by mr.fabe (thanks!), the gold dot on the top probably indicates a 5% tolerance, but there are no other color codes and I can't relate the "20b" to a voltage. I don't think the blue body color has any meaning other than a manufacturer preference.

Offline cprobertson1

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Re: Replacement tantalum: are they colour-coded?
« Reply #8 on: March 06, 2018, 07:08:57 pm »
@mahi: I think this thread might be more to your liking (I didn't check to see if you had already posted there I'm afraid!)

In other news - I think I've got my Wavetek 178 function gen fixed - though, I have to share a  :palm: moment!

I hooked it up to my scope and noticed the amplitude was twice what I set it as! So I took out my TRMS multimeter and poked that in the BNC connector... sure enough 2x too high!

Yup - you guessed it! I forgot to terminate the coax - 50 ohm terminator and voila spot on!

Whoooooooops!
« Last Edit: March 06, 2018, 07:13:29 pm by cprobertson1 »
 


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