Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Ekreks on April 21, 2025, 05:02:41 AM

Title: Crack Assembly Error - Connected 21U to 16U by mistake [resolved]
Post by: Ekreks on April 21, 2025, 05:02:41 AM

My Crack unit passed Resistance checks, was moving on to voltage checks, plugged the unit in saw a little smoke by the 16U cap, powered down immediately. realized my mistake - made the correction.  My question is given I saw a little smoke, I figure I blew the capacitor at 16U. What other damage did I do ? ...and what parts need to be replaced outside of the capacitor?

Thanks for any help.  I feel I was soo close.

Ekreks

Title: Oops - connected 21U to 16U by mistake
Post by: Ekreks on April 21, 2025, 05:38:42 AM

Hello:

I mistakenly connected the 5kw resistor to 16U and 21U by mistake, it should have been 21U and 15 U. I saw smoke from the capacitor, likely blown and needs to be replaced. Any other damage or parts need replacing? I checked the rectifier diodes they ae fine blocking one way, allowing the other.  I do have an lcr meter and checked the caps, they all report 200ish microfarads, I will still replace one I saw the smoke from. I checked the transformer primary and secondary side resistances

I have corrected the wiring. 21U to 15U.

Thanks for any insight/help. Boy do I feel dumb, looked things over and not sure how I missed this. I feel I was so close…

David

Title: Re: Oops - connected 21U to 16U by mistake
Post by: Doc B. on April 21, 2025, 07:11:28 AM

Can you tell us what kit you are building? That will help us to get your post moved to the proper board and we can better assist you.

Title: Re: Oops - connected 21U to 16U by mistake
Post by: Ekreks on April 21, 2025, 07:16:34 AM

The bottlehead Crack It. I tested the value of the 270 ohm resistors, the one I mis-wired went bad as well.  I ordered some replacement parts caps and resistor.to replace (correctly).

Title: Re: Oops - connected 21U to 16U by mistake
Post by: Ekreks on April 21, 2025, 09:22:18 AM

I see topic was moved, thanks.  I'll stand by for any insights. 

Title: Re: Oops - connected 21U to 16U by mistake
Post by: Paul Birkeland on April 22, 2025, 05:58:53 AM

Probably just that resistor needs to be replaced.  The capacitors generally will only fail if you put them in backwards.  Voltage never got to the capacitor mounted to 14/15, so there would be absolutely no reason to replace it.

Title: Re: Crack Assembly Error - Connected 21U to 16U by mistake
Post by: Ekreks on April 22, 2025, 07:06:02 AM

Thanks. My LCR meter is reporting the cap is fine. When replacement comes in I'll report back and close this out - hopefully successful..Cheers.

Title: Re: Crack Assembly Error - Connected 21U to 16U by mistake
Post by: Ekreks on April 23, 2025, 02:52:53 PM

Yep. Changed the resistor and all works fine now. Thanks! Unit sounds great.  Dead quiet, needed to drive the signal a little more to the amp, but once I got that balanced, all is well. now on to the speedball.  Cheers!