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Old 25th May 2005, 12:55 AM   #1
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I tried installing some 1 ufd SMD poly film caps today in a SI amp. After 30 minutes, I give up. I installed 4 ceramics 2.2 ufd in a 806 package in 15 minutes.
These are in a 1210 package. All measured 1.02 - 0.98 on my LCR meter. Email if wanted, I can put in a letter. There are 19 of them.
The repeated attempts to solder to the small pads did not short the one tried, but its measured value dropped from 1.01 ufd to 0.99 after about 20 tries at getting it stuck at both ends.
I was going to stack two to make a hillbilly 2 ufd cap. I could not get it to ever check continuity on both sides.
The 41Hz boards may have solder pads made for a larger cap. I looks like the stock 0.33 ufd cap is a 405 package.


George
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Old 25th May 2005, 01:13 AM   #2
Stocker is offline Stocker  United States
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Would you really not rather learn how to solder the caps instead?

I find that a small tool to push down gently on the center whilst soldering one end is a great help to soldering (expletive deleted) SMD components.
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Old 25th May 2005, 12:39 PM   #3
ohenry is offline ohenry  United States
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A bit off the topic, but would stacking the caps give a parallel instead of a series configuration? To double the values (= 2uF), wouldn't you want these in series?

Just curious, I'm not sure how this works. My intuition screams do them in series, but my intuition is often flawed...

Thanks for letting me stray.
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Old 25th May 2005, 12:43 PM   #4
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Caps are opposite to resistors.
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Old 26th May 2005, 05:50 AM   #5
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SMD components are the worst. The 41hz amp isn't much easier than the SI. I still haven't finished mine. Thanks for reminding me. It's time to get back to work on it.
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Old 26th May 2005, 06:15 PM   #6
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Pinkmouse is right.

Place two caps of equal value in parallel and you double the total capacitance.
Place two caps of equal value in series and you cut the total capacitance in half. (if both caps are 2.0 uf then in series the total capacitance would be 1.0 uf)
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Old 26th May 2005, 06:28 PM   #7
ohenry is offline ohenry  United States
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Thanks for the answers to my elementary question. I've read that somewhere in the past, but totally forgot. Then it came to me...

Old age is hell.

NOW...about a new home for those SMD caps. Any takers???
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Old 26th May 2005, 06:37 PM   #8
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Quote:
Originally posted by ohenry
Thanks for the answers to my elementary question. I've read that somewhere in the past, but totally forgot. Then it came to me...

Old age is hell.

NOW...about a new home for those SMD caps. Any takers???


No one has chimed in yet. Guess the ones who might try know about soldering oversized SMD poly fim caps. They are much tougher to do than the ceramics.
The ceramics transfer heat fairly well. I
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Old 26th May 2005, 06:43 PM   #9
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Quote:
Originally posted by ohenry
Thanks for the answers to my elementary question. I've read that somewhere in the past, but totally forgot. Then it came to me...

Old age is hell.

NOW...about a new home for those SMD caps. Any takers???


No one has chimed in yet. Guess the ones who might try know about soldering oversized SMD poly fim caps. They are much tougher to do than the ceramics.
The ceramics transfer heat fairly well. I have it possible to get them hot enough to melt the solder on both ends at the same time. This way an oversized cap came be wiggled around enough to drag a solder contact without actually sitting over the mounting pads.
The film caps do not tranfer heat, it is impossible to melt both ends with one iron. Maybe this is why the manufacturer recommends a hot air gun to install.

George
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