A part now out of stock...

Me again, asking for yet another substitute...
The 100uF electrolytic capacitor D55, Mouser part [http://gb.mouser.com/search/ProductDetail.aspx?R=647-UUX1H101MNL1GS] is currently out of stock with Farnell, so once again I'm looking for a replacement.

Will the following be OK?
[http://uk.farnell.com/nichicon/ucb1h101mnl1gs/capacitor-100uf-50v/dp/1580574]
It says case style radial, rather than D55. Idon't know what this means in terms of this kind of capacitor.

Any advice gratefully received as ever! I'm learning so much about the components already.
Hazel.

Both are electrolytic, 100uF, 50v (the voltage could be higher - it denotes the maximum voltage one can safely apply to the capacitor without turning it into fireworks). Both are SMT. Now, take a look at the dimensions: Mouser describes them as "10 mm Dia. x 10 mm L", while it is apparent from the photo, that the square black plastic pad under the capacitor is approximately the same size as the capacitor itself, maybe slightly bigger. So, it's 10mm on the side. Farnell, at the same time, lists "Width, External:10.3mm", and again, the pad is square. Now, for a given pad size, the actual electrical pads on the underside will be shaped, sized and placed the same way. So, this capacitor will fit.

Hazel,

If you want to stick with a surface mount part, you'll need to make sure the
contact dimensions are the same as the original part (and that the overall part size is either the same, smaller, or not enough larger to encroach on neighboring parts.
TI found the dimensions for the D55 package can be found at: [www.mouser.com]

(FYI, I searched for: SMT pad dimensions "D55"
)


The other specs to check:

Capacitance: same or larger

Working voltage: same or larger

Tolerance (on capacitance): same or *smaller* (less critical if you get a larger cap.)

ESR: Same or smaller (not that critical, a bit larger is tolerable, but no greater than +50%, at a guess.)


----

If you can't find anything available in the same/compatible package, you could also buy a leaded part and bend the wires to touch the pads, and hand solder them on. Certainly not as clean looking, but it would function. The electrical specs would still have to match/exceed.

If you pretend that a capital J is really the mirror of a capital L, then forming the leads something like this. Also pretend periods are blank spaces; hack to get code tag formatting to ~behave:


.----
|....|
|....| <-- leaded substitute cap
|....|
.----
.| |
.J L <-- Leads, bent to match pads, shorter is better

._ _ <-- pads
=============== <-- PC board



Excellent, thank you once again.
Hazel

Hi Larry,
OK, got it, I understand, thank you - except what is ESR? I've not seen that quoted for the Mouser part.
And also, how do you get your weblink actually to link?

It looks as if my suggested substitute will be fine.
Hazel.

For any one else reading this who is stuck for a particular SM capacitor resistor or LED. You can just as easily solder a standard leaded component on to the SM pads.

I bought the 1.1 Mother board very early before the kit was avalible and used axial resistors stood on end I think building like this was not as fiddly as hand soldering SM components.

The only constraint is you have is component size I have attached a link to a picture of the finished BD. Please note all of the connectors were recycled off old PC mother bds and network cards.

[picasaweb.google.com]

Tring to get a macro shot with a low cost digital camera leaves the picture slightly out of focus but you can see 1/8W 1% resistors standing on end.

---

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