Hard to find aluminum electrolytic capacitor

[sweetbeats]

50V 0.22µF 10% tolerance.

Its on a logic board in my Tascam 58...can't find one anywhere.

Anybody know anyplace that might have one, or are there some other resources that might lead to one?

[dgatwood]

Originally Posted by sweetbeats

50V 0.22µF 10% tolerance.

Its on a logic board in my Tascam 58...can't find one anywhere.

Anybody know anyplace that might have one, or are there some other resources that might lead to one?

Unless it is in the audio path, I'd just replace it with any old 0.22 uF cap from the Rat Shack with at least a 50V rating and no worse than 10% tolerance. If it is in the audio path, I'd probably swap it for film or something to improve the sound while I'm going to the trouble of swapping it. Either way, all that really matters is that you get the polarity right (if you replace it with an electrolytic), get the uF rating right, and pick a cap with at least a 50V DC rating.

If you really feel like you need a more exact match for some reason, though, get a couple bags of these:

http://www.amazon.com/Rubycon-Alumin...6391066&sr=1-6

or whatever, and buy a capacitance tester, then sort them by how far out of spec they are and find one that is within 10% of .22uF.... Shouldn't be too hard.

Wait a sec... an aluminum electrolytic capacitor... aren't ALL electrolytic capacitors aluminum-based?

Wait a sec... is this a surface-mount electro can? If so, then yeah, those are a little harder to find.

http://www.mcmelectronics.com/produc...LAID=220396952

But not that hard. Again, if you are really concerned about the tolerances, buy a bunch of 'em and test them yourself.

[sweetbeats]

Hmm...

Interesting idea...It is not in the audio path...It is on the Control PCB which handles all the transport controls and motor controls and such...It is the only cap in the entire deck that Tascam spec'ed at 10%, so that tells me it ought to be so.

Huh! So buy a bunch and measure them...

[antichef]

Don't take any advice from me, but how could a tighter tolerance ever be a problem? (unless they actually wanted a 0.2 µF, and tested a whole bunch of 10%'ers until they found one that bottomed out the spread?)

(p.s. I copy/pasted your µ symbol - cool!)

[evm1024]

What part number? (So I cn look at the schematic)

I'm wondering if it is in a timing circuit fot the transport.

-E

[Minion]

0.22uF Electrolytics aren"t very common though I have seen them in some cheaper gear (Not that the Tascam is cheap) ...

You shouldn"t have any problem replaceing it with a 0.22uF Poly film or even ceramic cap , Being a 10% cap tells me that the tollerance of the Cap and absolute value of the cap is not extremely critical....

Cheers

[evm1024]

I'm sure that you can find a 10% part out there somewhere. However, You might want to try this 20% part:

http://www.mouser.com/Search/Product...HLeV4NuQ%3d%3d

I would expect that your existing 10% is out of spec....

You could buy 10 of these and then measure them to select one that is within 10%.

I'm assuming that it is part of an RC circuit that forms a delay for some transport function. Let's assume that it is a 1 sec delay. +-10% runs you 0.9 to 1.1 sec. +-20% takes that to 0.8 to 1.2 sec. Not a huge difference but could be adverse.

Out of the batch of 10 you should get at least 1 that is within a few percent (provided the more precise parts have not been culled)

-Ethan

[sweetbeats]

Thanks everybody...I appreciate all the responses.

Being a 10% cap tells me that the tollerance of the Cap and absolute value of the cap is not extremely critical....

Correct, 10% does not indicate that it is critical, but because everything else was spec'ed at 20% (or greater), I'm assuming there is some reason why the 10% has some importance.

What part number? (So I cn look at the schematic)

I'm wondering if it is in a timing circuit fot the transport.

Ethan, it is C4 on the 58-OB Control PCB. FWIW its Tascam p/n 5260225710.

I can't even begin to decipher what it's purpose is when looking at the schematic.

[evm1024]

Page 5.1 section 5-2-1

C4 along with r21 and r22 are a wave shaper that adds a time constant (delay) in reading the end of tape. It drives U13. As part of a delay it was speced for 10%.

Parts are made and sorted based on how close they are to the target value. If the part is greater than 20% from the target is has an unspecified tolerance. If is is greater than 10% away but less than 20% is is a 20% part (Thus all 20% parts are at least 10% off the target value) If it is less than 10% error it is a 10% part. And so on. Of course if you don't sort for tighter tolerances you can get very clost to the target value.

So, I suspect that Tascam speced a 10% part to be sure that they had a time constant that was within a predictable range rather than to get a specific time. Does that make sense?

A selected part to be within 10% will cover you. I would not worry too much about the part. Other factors also effect the time period. The charging and discharge currents (resistor values and transistor source sink currents - of course caps have the greatest variance)

--Ethan

[sweetbeats]

Cool. Thanks so much.

So an out-of-spec cap in position C4 is going to effect a delay timing but nothing else? In other words the deck is not going to respond quite the way it was designed but that's not going to damage anything and at most be an irritant to somebody who straightens the tassles on their rugs?

And so best/simplest bet would be to spend a buck or so and get a smattering of 20% caps, test and stuff the one that is closest to rated value?

[dgatwood]

Originally Posted by antichef

Don't take any advice from me, but how could a tighter tolerance ever be a problem? (unless they actually wanted a 0.2 µF, and tested a whole bunch of 10%'ers until they found one that bottomed out the spread?)

The parts I pointed to were +/- 20%, so you might have to test multiple to get within +/- 10%.

BTW, in practice, you'll probably find that 20% parts are really 90% * value +/- 10%, i.e. they are unlikely to be over the specified value. BTW, I doubt that most capacitors are tested at all at the factory; chances are they test one out of every thousand or something. When you're dealing with cheap commodity parts (as opposed to... say... CPUs that actually are binned based on how fast they test successfully), the cost of testing each part would be prohibitive.

[dgatwood]

If there's room, here's a poly part with 10% tolerance:

http://www.newark.com/jsp/search/pro...FC-GB100000001

Of course with the $20 handling fee per order (shipped from the UK)... I'd probably just grab a 20% tolerance electrolytic off the shelf at the Rat Shack and be done with it.

[sweetbeats]

Thanks for the info, dgatwood...I've got a couple dozen 20% caps coming with an order from Mouser. I'll set the multimeter to 'capacitance' when they get here and see what I got.

I'll check out that poly cap you linked as well...might be able to source locally.

[sweetbeats]

So I went ahead and did as suggested and bought a couple bucks worth of the 20% caps in hopes of finding one that was right around 10%...Well, they were all well under 10%, and one was even under 5%!

I'm using that one.

Nichicon PW's.