1.6K Ohms resitor turned orange. [resolved]

clthrt01 · 5093

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Offline clthrt01

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on: September 30, 2015, 03:18:08 PM
Hello,

I finished my Tode last week.  Everything seemed to check out okay with the multi-meter (some output readings were low, but from some reading, that was to be expected).  I plugged it in, got about 2 notes out and it fizzled out.  Sounded like something fried inside.  A few seconds later I saw smoke.  The 1.6K Ohm resistor was orange-hot and, after it cooled, crumbled.  I replaced it, only to find the same problem.  Any idea what causes this?

FYSA, I'm new to this stuff.....this is my first build of this type.

Thanks
Mike
« Last Edit: October 06, 2015, 06:30:55 AM by Caucasian Blackplate »



Offline Doc B.

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Reply #1 on: September 30, 2015, 04:41:03 PM
Don't turn it back on, you have a major short somewhere. The burned resistor is a symptom, but not the problem. Best place to start is to go back over all your connections to make sure you haven't inadvertently wired something to ground that shouldn't be.

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline Paul Birkeland

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Reply #2 on: September 30, 2015, 04:45:16 PM
(some output readings were low, but from some reading, that was to be expected).

Which ones?

A backwards capacitor would cause this problem on its own.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline clthrt01

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Reply #3 on: September 30, 2015, 05:06:03 PM
At this point, I don't quite remember which ones.  I would have to go and redo them, which I can do tomorrow.

I think I might have found the short.  The shielded wire that jumps from A4 & 5 to B4 & 5 was fused together about a 1/4 inch above B4 & 5.  While soldering, apparently I let it get too hot and it melted the coating and the wires were touching.  Will this cause my problem, and now that they are separated, can I chance turning it on again?

Thanks
Mike



Offline Paul Birkeland

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Reply #4 on: October 01, 2015, 06:29:18 AM
That short would certainly keep your amplifier from operating, but I don't believe it's the source of your trouble.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline clthrt01

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Reply #5 on: October 01, 2015, 01:50:43 PM
Nope, it wasn't.  I also found that I had the poly cap attached to 18U instead of 19U......but that didn't solve it either.  I need to go through the directions step by step because I cannot find anything else that looks odd.   I must have attached something wrong.

Mike



Offline clthrt01

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Reply #6 on: October 05, 2015, 05:33:57 PM
Turned out to be a really simple issue.  Terminal 5 on the output transformer was touching the metal speaker frame.  I bent the tab in, away from the speaker and viola.

Thanks, pretty cool little amp that I now want to build a cab for so I can hear it through a 12" speaker.



Offline Paul Birkeland

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Reply #7 on: October 06, 2015, 06:30:43 AM

Thanks, pretty cool little amp that I now want to build a cab for so I can hear it through a 12" speaker.

I'm glad you got it sorted!  Don't limit yourself to one 12" speaker, go for a 4x12!

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline clthrt01

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Reply #8 on: October 06, 2015, 02:29:29 PM
Pretty sure my wife would kick me out if I did that.....