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Old 13th January 2009, 10:27 PM   #1061
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I got this one over a year ago and it works great. Tips same size as the Hakko. The thing is great.

Still desperately seeking a couple boards

desperately
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Old 13th January 2009, 10:42 PM   #1062
pchw is offline pchw  United States
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Quote:
Originally posted by mpmarino
I got this one over a year ago and it works great. Tips same size as the Hakko. The thing is great.

Still desperately seeking a couple boards

desperately
Hi Marc,

I didn't see your previous post. I have 4 boards and can send 2 to you. Given the workload that I am having, I doubt that I will see any kind of soldering issue any time soon Let see I can dig out your email address -)
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Old 13th January 2009, 11:14 PM   #1063
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I got my Hakko on sale at Fry's and I'm the one having the trouble. Hmmmmmmmmmm I have to say the tip does last a long time and it does heat up fast. Here's a pic of one of the boards. Any opinions?? pchw- I need 2 boards too- email me!!
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Old 13th January 2009, 11:21 PM   #1064
clm811 is offline clm811  United States
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Default O.T. on soldering irons

Quote:
I used throw away irons until I bought my... temperature controlled station. Results are worth it and the tips last a >10X longer than the cheap irons.
I agree with Bob!

I may wear out the $3 tip for for my back-up Rat Shack 40W iron this week as much as I've been soldering on these PCB's; However, my $8 Weller WTC tip has lasted well over a year with regular use, plus you get constant temp control(i.e. not too hot/not too cold-just right)!
I got my Weller while in college and it lasted 20+ years (OK-I'm spoiled). Too bad they cost a fortune now(even on ebay).

-Chas

BP: We may be able to salvage your boards yet!

Please see the photo on how I start each resistor lead (solder top first, flip board and solder bottom(after trimming lead to 0.25-0.5"). Oh, and for a tightly-clustered bunch of components, I stuff and solder one at a time starting near the center of the group. Time consuming? yes. Problems? no.

Lesson learned:If buying surplus resistors, check lead material(avoid steel )! Cheaper isn't better!
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Old 14th January 2009, 12:24 AM   #1065
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Bob,
This is what I believe was the the problem. I used a resistor with extreemely thin coating over steel leads. I buffed the leads and Chas did not. He was able to get his to adhere to the solder because he had not buffed the lead. I, instead, tryed to make the lead even smaller removing all the tinned coating. I then tried to solder the the steel wire to no avail. Does this make any sense??

BP
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Old 14th January 2009, 12:52 AM   #1066
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Sounds like that could cause a problem. Can you make the leads small enough to tin before placing and still get them through the holes?

Others can help your soldering skills more than this far from expert.
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Old 14th January 2009, 12:58 AM   #1067
rob3262 is offline rob3262  United States
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Quote:
Originally posted by tryonziess
Doesn't anyone use a cheap 8.00 dollar 40 watt iron anymore. I never did enough soldering to justify spending 80.00 dollars for a decent station. When the little guy dies I just buy a new one.

Tad
Heck, I run a 260/200W Weller gun on the big stuff! These things are 'acquired' over the years.
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Old 14th January 2009, 09:45 AM   #1068
AndrewT is offline AndrewT  Scotland
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Default Re: Re: Boards....

Quote:
Originally posted by rob3262
Matching zeners was as bad as small signal transistors. I'm beginning to think that 5% is useless! My reference voltages range between 19.2 and 19.8V Maybe I'm anal but I was hoping to exact match 6 boards!
matching the near 40V required from the pair of series Zeners is easy.

Set up a DC supply with a limiting resistor (30V and 1k2 will do)
This passes ~8mA through a 20V Zener. A 400mW Zener will not run too warm @ 170mW.
Now measure all your Zeners.
find pairs that add up to a fixed voltage near 40V, eg 19.9+19.2=19.7+19.4=19.1+20 etc.
Job done.
Final check on the assembled and powered PCB. See if the total Zener voltages are within 0.1V
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Old 14th January 2009, 10:05 AM   #1069
rob3262 is offline rob3262  United States
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I actually had set the supply for a 2ma flow thru 1k resistor, DC voltage was ~ 21.5v during the test.

I really hope I didn't fudge the test as all the diodes are paired off already. And four soldered to a board. Matching the first 16 was easy, but as the pool got smaller, well....

The last set of zeners have a .1v mismatch. I was satisfied to get that result.
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Old 14th January 2009, 10:38 AM   #1070
AndrewT is offline AndrewT  Scotland
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that 1.5V across the resistor will affect the accuracy of the testing.

if you put a 19.9V Zener in it will leave 21.5-19.9=1.6V across the 1k0, passing 1.6mA through the Zener, ~32mW (<10% 0f 400mW rating).
now put in a 20.1V Zener. It will pass just 1.4mA. this is even less than the 32mW of the previous and will result in a voltage measurement that is not comparable to the first test.

You need a more consistent current source. Either a higher regulated voltage or a CCS.
I recommend that Zeners dissipate >=10% of rated power for consistent voltage regulation.

But the final test is in the powered amp, that is the one that matters.
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