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zaubertuba  
#1 Posted : Saturday, February 11, 2017 5:22:43 AM(UTC)
zaubertuba

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So, I mis-wired a project to my LCBPS, and had a "magic smoke" failure of the third degree (D1 exploded right off the board! O.O ).

I've replaced D1 (double-checked polarity) and also the LM317 regulator, but the maximum I can coax out of the positive side is only +8.7-ish volts. What else could I have killed?

Edited by moderator Wednesday, March 1, 2017 9:03:04 PM(UTC)  | Reason: Not specified

Brian Donegan  
#2 Posted : Thursday, February 16, 2017 2:10:10 AM(UTC)
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Probably replace D3 and check capacitors for shorts. What voltage to you measure across C3's pins?

Edited by user Thursday, February 16, 2017 2:10:54 AM(UTC)  | Reason: Not specified

zaubertuba  
#3 Posted : Friday, February 24, 2017 11:50:39 PM(UTC)
zaubertuba

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Originally Posted by: Brian Donegan Go to Quoted Post
Probably replace D3 and check capacitors for shorts. What voltage to you measure across C3's pins?


Replaced D3, same result. Voltage across C3 is approx. 28 Volts--so was the voltage across C4.

The confusing thing is C3, C4, C5, and C6 also appeared to test as open. I pulled C3 and verified it. I dunno, maybe my multimeter is registering too fast to check or is otherwise faulty. Think

Brian Donegan  
#4 Posted : Sunday, February 26, 2017 5:49:23 PM(UTC)
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Capacitors will generally test as open with a continuity meter (depending on the meter). You should use a capacitance meter if possible.

What is the AC input voltage? 28V would suggest something close to 20VAC.

Is it possible you damaged the through-hole plating when desoldering?

Edited by user Sunday, February 26, 2017 5:50:04 PM(UTC)  | Reason: Not specified

thanks 1 user thanked Brian Donegan for this useful post.
zaubertuba on 2/26/2017(UTC)
zaubertuba  
#5 Posted : Sunday, February 26, 2017 11:04:58 PM(UTC)
zaubertuba

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Originally Posted by: Brian Donegan Go to Quoted Post
Capacitors will generally test as open with a continuity meter (depending on the meter). You should use a capacitance meter if possible.

Yeah, my MultiMeter is pretty cheap, maybe time for an upgrade. ;)

Quote:
What is the AC input voltage? 28V would suggest something close to 20VAC.

I'm using an 18V-0-18V Transformer, it's inputting about 21.5V AC

Quote:
Is it possible you damaged the through-hole plating when desoldering?

You nailed it...I messed up the via on the LM317 pin two--the top pad was open to the pin. Soldering the top pad to the pin fixed it. Muchas Gracias! :)
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