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Old 23rd August 2013, 10:16 PM   #2951
jcx is offline jcx  United States
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There is a legend in Africa that speculates that elder elephants knowing that their death was imminent left their herds and traveled to a place known as the ...
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Old 23rd August 2013, 11:12 PM   #2952
Kindhornman is offline Kindhornman  United States
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jcx,
The Boneyard! It isn't even that some of these things are small as much as some of us are getting blind as we age! I know I will have to put on my magnifying lenses to work on a smd or else forget about it. I just haven't had to deal with any so no experience. Not really afraid to start just haven't had the opportunity or the need up to now.
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Old 24th August 2013, 12:04 AM   #2953
rsavas is offline rsavas  Canada
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My first job out of college was at Motorola, it must have been one of the first SMT production lines in N/A, ~1985, had a FR4 and a ceramic substrate hybrid line, running in parallel.
One day a green ME did a test around lunch time, put an FR4 pcb through the hybrid line, smoked to whole place out, people sick/fire dept etc, got to go home early that day. :-)
Yes magnification is the answer.
All for SMT, for many assy's, it really is a mix of SM/TH. Paste/glue/reflow/wave/back-load etc.
P.S. still got parts I picked off the floor while fixing the pick/place machine. Now have a LCR meter, so can finally sort them MLC caps out.
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Old 25th August 2013, 01:37 PM   #2954
grhughes is offline grhughes  United States
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All you young guys with perfect vision go for SMT. My eyes are not what they used to be. Personally I don't relish chasing a SMT part around a 1 inch square board with while holding a magnifying glass or wearing uncompfortable visors or peering through a microscope. I haven't built anything since about 1980 and I have a drawer full of matched 2n4401/03 in TO92 and I don't want to go through that pain of matching again. I would rather have holes to anchor the part before I solder it. Call me a dinosaur or whatever. I'll probably only build four of Scott's preamps and that will be it, so why invest in all the paraphenalia I would need for SMT. So please consider a thru hole board for us aging dinosaurs, PLEASE. Ray
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Old 25th August 2013, 03:23 PM   #2955
bcarso is offline bcarso  United States
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The advantages of SM are manifold. It's possible to get performance at high frequencies that simply isn't accessible with radial/axial components. But they are difficult to work with. You can however sometimes get subassemblies with SM on little boards that convert, say an SO-8 to an 8-pin DIP. But you lose performance advantages with the added parasitic inductances (in particular).

I designed an elaborate hybrid analog and digital board for Epson America, for a home theater system, which went into the motorized screen and was both a motor controller and IR receiver/processor. I was rather pleased with how I managed to infer the motor condition, including its internal and otherwise inaccessible limit switches, looking at phase and transmitting signals across a galvanic barrier. I brought in an early version to show them, and the thing that they were impressed with is how I'd managed to put it together, as there were a lot of surface mount parts
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Old 26th August 2013, 02:33 PM   #2956
rsavas is offline rsavas  Canada
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If you do the math, I ain't young (54) but god did bless me with being very myopic, which in the case of small, is very good. Must realize that SMT is geared for automated assembly, period.
I have done some big pcb's, where I designed, gave to fab, got an assembled pcb back, with some BGA pkg's used, so it really is the economics of scale. If everything worked, as it should, I did not even have to touch a soldering iron.
Yes as DIY, THT is the best for all concerned, but I want to use a BF862 or one of those duals in a SOT-363? and NXP don't want to bother with a THT pkg, so it is, use what ya got and most possibly limit yourself, or get with the times.
Actually those clowns, finally standardized on the pin out for a bjt/fet in a SOT-23, where as, for say a T0-92, it is scattered about and thus is a PITA.
Awful shame that this SMT issue limits many a man's horizons, so that ends the story for me.
Rick

Last edited by rsavas; 26th August 2013 at 02:39 PM.
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Old 26th August 2013, 04:52 PM   #2957
luvdunhill is offline luvdunhill  United States
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Quote:
Originally Posted by grhughes View Post
I haven't built anything since about 1980 and I have a drawer full of matched 2n4401/03 in TO92
I am curious, why this project would end that streak? If a modern monolithic opamp hasnt ended this trend already, why should this?
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Old 26th August 2013, 06:03 PM   #2958
grhughes is offline grhughes  United States
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I'm retired now. All my kids have grown and out of the house and I have time to upgrade my gear that I built in 1980; replace all the electrolytics, etc. Is that enough of an answer? Ray
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Old 26th August 2013, 06:18 PM   #2959
bcarso is offline bcarso  United States
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Quote:
Originally Posted by grhughes View Post
I'm retired now. All my kids have grown and out of the house and I have time to upgrade my gear that I built in 1980; replace all the electrolytics, etc. Is that enough of an answer? Ray
At least most electrolytics will be large enough to be seen.

I finally had to replace one in an NAD3020. Considering I'd used the amp since circa 1980 as well, I hardly was surprised. And it wasn't even one of the big bulk caps, rather one of the auxiliary higher-voltage rail ones. Of course I changed both aux rail ones together. I looked at the ripple on the main rails and it was still just fine, so I decided not to bother with those. Of course the switches and the volume pot have long ago gone south, so I simply run into the power amp input on the back.
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Old 26th August 2013, 06:32 PM   #2960
rsavas is offline rsavas  Canada
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Of course the switches and the volume pot have long ago gone south,
Past Deoxit and disassemble/clean with eraser etc?
Parts not avail either, so need to jump on the S/S, relay and CS3318 bandwagon.
Need a pre-amp, with no pots, switches, in the sig path, got one for sale :-)
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