Tantalum decoupling caps

[Electrobumps]

Yes it is worth it - the tantalums should be easier to remove than the power supply electrolytics.

should be…..but the PSU electro caps were relatively easy to remove. The motherboard electro’s were a challenge. Doesn’t matter how you do things some boards are just tricky and liable to track lifting when working on.

 

[Brian Roth]

should be…..but the PSU electro caps were relatively easy to remove. The motherboard electro’s were a challenge. Doesn’t matter how you do things some boards are just tricky and liable to track lifting when working on.

Another factor is the age of the board. On a blank board, the thin copper "foil" was "glued" to the plastic substrate. Then the pattern was etched into the foil resulting into many thin traces.

Time and heat often causes the copper traces to loose their original adhesion to the plastic substrate. Hence, boards in decades-old equipment have become more fragile.

Bri

 

[Brian Roth]

Somewhat related, I've also encountered small (matchhead sized or less) ceramic bypass caps fail as shorted across power rails. Here's an example of what I'm describing:

https://www.mouser.com/ProductDetai...s/K104K15X7RF53H5?qs=sYfpZ29HcUSlgH5bSUHkYw==
More than a few pro audio products have a pair of those boogers located at each opamp...one per rail. Imagine a few dozen opamps in a console module, and hence dozens of those caps across each rail!

Bri

 

[RoadrunnerOZ]

should be…..but the PSU electro caps were relatively easy to remove. The motherboard electro’s were a challenge. Doesn’t matter how you do things some boards are just tricky and liable to track lifting when working on.

Try desoldering the voice filter IC’s from a Juno 106 - the tracks running between and off the pins are 0.3 mm wide. I don’t know what Roland were thinking there. Litz wire can be your best friend for repairing lifted print. If you’re careful and know how to tackle fine print you won’t lift it even if it’s old - but some just let’s go anyway. I’ve done countless switch pot removals and repairs on Neve consoles that are 40 years and more of age and learnt to be patient and how to determine the right amount of heat without blitzing superfine PCB tracks especially the hidden ones that run underneath. I have rebuilt AMS, Eventide, Pultec, Lexicon, RND, TC Electronics, Quantec, Clark Teknik, Sony, Alesis, Yamaha, Orban and so on - the removal of components can be a bitch but you need to be cognisant of how far you can take things before they turn pear shaped. I’ve cursed designers for their lack of foresight in design for future service, but that never fixes the unit. Some design attitudes were “this was made in Germany, or USA or the UK or anywhere and should never need fixing” - wrong!

 

[Somkereki]

old tantalum capacitors have a track record of failing short circuit that can cause serious problems across PS rails.

JR

Or a very high ESR value! In the summer, I also had to replace all the tantalum capacitors in my Neutrik A2 - D "Audio Test & Service System device with foil capacitors! But a long time ago, they also occasionally caused unpleasant surprises in my Uher Report Stereo tape recorder, and in the end I replaced them all with aluminum electrolytic capacitors (selected) + parallel foil capacitors. For about 15 years, I was an audio technical service technician for Hungarian theaters, they caused a lot of problems with the professional Sennheiser microport transmitter and receiver devices. I got to know them from the nature of the noise. It was like a person walking in freshly fallen snow, it had such a character, it cannot be compared to anything else. When I plan something, I never I don't put a tantal capacitor in it. The filter capacitors on the power rails are not always suitable. Few people know, but there is a limited "slew rate" data in the catalogs. (at least it was written about 40 years ago.)

 

[Somkereki]

Why is that?

Or a very high ESR value! In the summer, I also had to replace all the tantalum capacitors in my Neutrik A2 - D "Audio Test & Service System device with foil capacitors! But a long time ago, they also occasionally caused unpleasant surprises in my Uher Report Stereo tape recorder, and in the end I replaced them all with aluminum electrolytic capacitors + parallel foil capacitors. For about 15 years, I was an audio technical service technician for Hungarian theaters, they caused a lot of problems with the professional Sennheiser microport transmitter and receiver devices. I got to know them from the nature of the noise. It was like a person walking in freshly fallen snow, it had such a character, it cannot be compared to anything else. When I plan something, I never I don't put a tantal capacitor in it. The filter capacitors on the power rails are not always suitable. Few people know, but there is a limited "slew rate" data in the catalogs. (at least it was written about 40 years ago.)

 

[Somkereki]

AND, in many devices that had a LOT of tantalum capacitors used as power supply bypass, locating the particular cap that was causing the power supply to fail (because of the tant short) was an absolute NIGHTMARE. That's why audio DIY guru Rod Elliott has described tantalum capacitors as fit only for the wastebasket.

I agree ! I spent a lot of time looking for tantalums that cause periodic noise. In theaters, they can cause very unpleasant noises in microport transmitters during performances!

 

[Newmarket]

Let's take a veer. Any thoughts on tantalum resistors ?

 

[Tubetec]

'......Amazing transparency ,highly musical and detailed , other resistors dont even come close '
The high cost obviously maximises the placebo effect too

 

[RoadrunnerOZ]

“….sound less dry than the metal films and they do not emphasise any particular frequency range. They sound more natural, more musical….”
You’d want to get your $20/resistor worth. Imagine “re-resistoring” a recording console

 

[CJ]

Tantalum mines are a pretty brutal place to work so I am doing somebody a favor if I don't use them , in my mind at least, as the cell phone market will keep people digging in the dirt for eons,

Remember that shortage that created the 2 year lead times?

 

[RoadrunnerOZ]

Tantalum mines are a pretty brutal place to work so I am doing somebody a favor if I don't use them , in my mind at least, as the cell phone market will keep people digging in the dirt for eons,

Remember that shortage that created the 2 year lead times?

My Scottish great grandfather started working in the deep coal mines at 10 years old in the northern UK. He started as a hurrier (cart puller) pulling carts of coal through tunnels on hands and knees to the pit bottom from the coal face. Children and women were employed as pullers and pushers of carts of coal, men of any strength as “getters” - they lay down in the tunnels with a lamp and a pick axe and chopped out the coal to fill the carts. There was no future other than coal mining in those areas, without that work the family starved - everyone worked the mines. I think the same could apply for these workers - may be brutal, but may be the only work available. The life expectancy was little over 60 if you were lucky. The tubs and the coal could weigh over 600kg, and would have to be moved through roadways which were often only 60-120cm high.


In contrast on my other side of the family my grandfather born 1876 lived until 1970, a farmer all his life and retired at 88 still doing 12hr days, 7 day weeks. Big contrast…..

 

[gyraf]

small (matchhead sized or less) ceramic bypass caps fail as shorted across power rails

yes, those modern MLCC capacitors are very much accident-prone in much the same way as tants - in some cases even worse

A handful of years ago I optimistically decided to replace all production 10uF electrolytics in power decoupling duties with MLCC version - just to ensure long life in the commercial Gyraf's. Yes, a 10uF/35V ceramic capacitor is commonly available today, and I always expect ceramics to last forever.

I managed to use them for a year and a half, then they started to come back to haunt me - first I thought I'd been unlucky or perhaps applied too much mechanical stress to them. But no: One after another more than a third of them short out and cause all sorts of problems.

Internally they're codenamed "those yellow peskies" - and ALL are always to be replaced on sight

It was simply a stupid move deciding to replace the electrolytics - a case of counterproductive hyperoptimisazion. Looking back, I realize - to add insult to injury - that I have not ever had to replace one of those 10uF electrolytics.. :sigh:


/Jakob E.

 

[Newmarket]

You guys with your tantalum resistors !
Old hat - the action is with Niobium now ???

"Niobium has never been used in a resistor as far as we know. We looked at its properties and felt it was worth testing, and discovered that it is finer and more even sounding than Tantalum."

 

[RoadrunnerOZ]

I managed to use them for a year and a half, then they started to come back to haunt me - first I thought I'd been unlucky or perhaps applied too much mechanical stress to them. But no: One after another more than a third of them short out and cause all sorts of problems.

MLCC failures can be attributed to cracking and moisture ingress or spot layer inconsistencies or impurities in the manufacturing process. Cracking happens easily with smd MLCC caps on boards that flex due to heat coupled with applied voltage, just add humidity and you have quick failures. Even post manufacturing stresses due to board soldering can cause cracking leading to moisture absorption. Constant vibration can cause similar stresses in the multi-layered ceramic. I guess maybe audio is not a good environment?

 

[Tubetec]

Im not sure where the 'dry sounding' adjective comes in with resistors ,
to me a dry sound means without room ambience or added effects ,
nothing remotely to do with the composition of the resistors .

Coltan mining has a terrible impact on the environment and the people who work there ,
yet we have the woke/save the planet crowd who go into withdrawl and subsequent meltdown without their social media fix . If TV was the drug of the masses in the old days this new **** is more akin to fentanyl for all .

 

[RoadrunnerOZ]

I think Niobium and Tantalum come from the same ore. It seems like a step back in time with mining like this which shares none of the wealth with the miners - they’re glad of work but they should be rewarded and the process mechanised- it’s their land

 

[Newmarket]

MLCC failures can be attributed to cracking and moisture ingress or spot layer inconsistencies or impurities in the manufacturing process. Cracking happens easily with smd MLCC caps on boards that flex due to heat coupled with applied voltage, just add humidity and you have quick failures. Even post manufacturing stresses due to board soldering can cause cracking leading to moisture absorption. Constant vibration can cause similar stresses in the multi-layered ceramic. I guess maybe audio is not a good environment?

Have a look at "Flexi term" parts where there is "give" in the termination.

 

[Newmarket]

Im not sure where the 'dry sounding' adjective comes in with resistors ,
to me a dry sound means without room ambience or added effects ,
nothing remotely to do with the composition of the resistors .

It's meaningless subjective nonsense even if the company's audio products are nice.

 

[RoadrunnerOZ]

Have a look at "Flexi term" parts where there is "give" in the termination.

Someone spotted the problem - automotive computers used to give lots of problems. Aston Martin cleverly put a computer for engine management on one particular model right in the middle of the engine on top!