Capacitor replacement in old ECU's

[YLD-16L]

Hi all

There has been plenty of occurrences noted on here of old ECU's playing up or failing due to capacitor issues and many instances of great success after replacing the capacitors.

Now I understand that it is generally the electrolytic capacitors that are being replaced as they leak and break down internally with old age.

My question of the electronic savvy is, do tantalum capacitors also breakdown or fail in any way or are they generally stable for very long periods compared to electrolytic capacitors?

Thanks in advance.

[river]

Hi,

They are more stable, and don't leak. Also get one rated above the voltage by a good percentage (ie use a 30-50V cap for 12 V).

seeyuzz
river

[The Witzl]

what river said.

However tantalum caps are generally more expensive, and are far less tolerant of voltage spikes above their rated voltage - they go boom much more easily.
They are typically only available in lower votlages too (ie. 50V max), and thus only suitable to low votlage applications.

In all other aspects, they are better.

[YLD-16L]

Cheers lads, that's what I needed to know

Rep has been dished out accordingly.

[The Witzl]

I just checked... we have a pretty decent range of tantalum caps in Jaycar.
Even the pesky 15uF that is missing from almost everyone's range of electrolytics

[petergoudie]

My understanding of tantalums is that apart from what has been said above they basically last forever as their construction is quite different. Whilst Jaycar might have some sizes, RS Electronics are better but charge several times more as they hold enormous stocks. Better still though is to search eBay international because you can buy a bag of 50 or 100 for very cheap prices from the US. The average upper voltage range is 20 or 25 volts and higher than this are hard to find.

[river]

Hi,

Not only can you get them at Jaycar (and Dickhead Smiths) but Rockby (www.rockby.com.au) often have specials with tants. And you can try Excess Electronics (www.excesselectronics.com.au) for some really cheap stuff.

When I was a trainee techo back in the dim dark days, we used to play a joke on the other techs and put in a 5v tant, reversed polarity, on another techos 12v power rail. When they turned on their machine you'd hear a mini "bang" and a puff of smoke. Some knew what was going on, but others were totally clueless.

But, getting back to the topic at hand, I suppose if you wanted to protect the tant from spikes you could always put a zener across its legs. So, for a 12v tant you could put a 12.7 or 13v or even 15v zener across its legs to dissipate any spikes. For a 5v tant you could use a 6v zener. Just a thought... and one I admit I haven't tried. I'd have to check the data sheet for the relevant zener for its spike rejection ability to see if it was worthwhile.

seeyuzz
river

[The Witzl]

We (Jaycar) stock most values in 16 and 35V rating.
However the larger capacitance values, >10uF, are only stocked in 16V.

For just replacing the caps on an old ECU - i wouldnt dream of ordering from RS. The price of the caps and shipping alone would be more than sending the ECU to a service technician to be totally rebuilt.

[river]

Hi,

I got an RS catalog and by crikey, by gee, by jingo... they ain't cheap.

seeyuzz
river

[The Witzl]

yeah i have to keep laughing at them when their state sales manager comes into the office trying to sell to us. I keep reminding him that our SELL price is lower than our high volume buy price from RS.

[TERRA Operative]

When I do cap replacements in ECU's I use 105oC rated Nichicons (Sometimes Rubycons or Panasonics, depending on avaliability), preferably from the ZL series (High ripple rejection etc).
The high temp rating ensures a long life in the environment they're installed in.

[Sciflyer]

We (Jaycar) stock most values in 16 and 35V rating.
However the larger capacitance values, >10uF, are only stocked in 16V.

For just replacing the caps on an old ECU - i wouldnt dream of ordering from RS. The price of the caps and shipping alone would be more than sending the ECU to a service technician to be totally rebuilt.

Sometimes you dont have a choice as some of the caps are in less common values/voltages/package sizes/temp ratings

Ive had to order from RS for ECUs and PC motherboards before as Jaycar/DS/Altronics etc dont have the correct caps, i know for a fact you cant get all the ones to do a Z30 ECU

[The Witzl]

Sometimes you dont have a choice as some of the caps are in less common values/voltages/package sizes/temp ratings

Ive had to order from RS for ECUs and PC motherboards before as Jaycar/DS/Altronics etc dont have the correct caps, i know for a fact you cant get all the ones to do a Z30 ECU

yeah in tantalum the range probably wont cover an entire ECU, as our range only goes up to 47uF, so the big 220uF and 100uF caps arent covered.... but in electro the range should be sufficient.

Worst case scenario is piggybacking a few caps to get the right value

[TERRA Operative]

Do Jaycar stock Nichicons or Rubycons etc. yet?

[The Witzl]

nope... and dont intend to.
We sell to a price, and those brand caps cost about 4 times what we buy for.