Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: lups1 on January 16, 2014, 05:03:42 AM

Title: Transformer going hot, and making a noise
Post by: lups1 on January 16, 2014, 05:03:42 AM

So I finished my crack , measured all the Impedances and they look perfect ,maybe except for the RCA Jacks which show 106 KOhm not 90-100. But when I turned the crack on , the Tranformer is loud, and gets really hot in few seconds. I might add that the firs Fuse was blown and as I had only one 1/2A fuse Ive put in a 2A one which doesnt get blown. The tubes dont start glowing. I Think that the orientation of the Transformer is fine , Ill add a picture. Has anyone encountered a similiar problem?

Title: Re: Transformer going hot, and making a noise
Post by: ffivaz on January 16, 2014, 05:15:02 AM

I would check that your rectifier diodes (UF4007, p. 27 of the manual) are correctly oriented, in the correct terminals and that they are not shorted or fried. It is difficult to see from your picture.

Title: Re: Transformer going hot, and making a noise
Post by: Paul Birkeland on January 16, 2014, 08:42:04 AM

I'd start by moving that twisted pair of wires from power transformer terminals 4/5 down under everything else.

Then, go back to the manual and rework your Crack until it looks as close to the manual as possible. 

I think Ffivaz is most likely correct.  The fuse will blow and the power transformer will vibrate because there's a huge load on it.  In your case, I believe you have a short in the amplifier, or a backwards diode.

Title: Re: Transformer going hot, and making a noise
Post by: Doc B. on January 16, 2014, 08:50:02 AM

You should also trim the excess wire that is coming through a lot of the transformer terminals. Some are so long that they could short to a neighboring terminal. As PB says, try to emulate the look of the amp photographs in the manual.

Title: Re: Transformer going hot, and making a noise
Post by: lups1 on January 16, 2014, 09:35:12 PM

Oh god , I really did have the uf4007 misoriented...Im more then sure that I double checked for that;D Thank you guys , now everything looks fine , I only have to do the voltage tests now.