bad solder joints or something else ?

[captain widwiki]

Hi,

I've finished the building and the resistance check is ok, but when I turn the amp on to check the voltage, the tubes don't glow at all and fuse insn't blow. I've searched throught the forum and i found that it may be bad solder joints on transformer terminal 4 and 5 or tube pins B8/B7/A4/A5 and B9 so  I've check all solder joints but i have to admit that i am beginner in soldering so here some picture... Thank you

 

[JamieMcC]

I thought my 12au7 tubes didn't glow at first when actually did, can you darken your room and check again?

I am looking at my tubes right now in the daylight and can not see any glowing but the music is indeed flowing very nicely.

 

[Grainger49]

First, to address what you mention in your post:

What kind of solder are you using.  I  don't like the looks of most of your solder joints.  They are dull. 

For instance, in the last picture the left LED, left lead, the solder joint at the tube pin has a lot of brown on it.  The tube pin to the right of this one shows the wire black and tube pin looks rusted.  There doesn't seem to be much solder on the joint mentioned in the last sentence.

Of course there are a number of places a newbie can have problems.  The diodes must be oriented properly (white banded side is the key), including the LEDs (silver banded side is the key, and the two on the 12AU7 are right).  The capacitors must be oriented properly, the white striped side is the key here to.

Next, the place to start is any voltage that is 15% out of spec, plus or minus.  Post the terminal or tube pin number, the expected voltage and your voltage.

 

[Paul Birkeland]

I've finished the building and the resistance check is ok, but when I turn the amp on to check the voltage, the tubes don't glow at all and fuse insn't blow.

What do you get for your voltage checks?  There's a big difference between having no glowing tubes and 0V DC everywhere, and no glowing tubes and ~200V in certain spots.

Are you sure you put the fuse in the correct place?  What is the AC voltage between power transformer terminals 1 and 2 with the power on?

-PB

 

[captain widwiki]

I've used solder with 4% of silver first. The second time i've use solder with lead. The Voltage of Transformer terminal 1 and 2 are both 230, others terminals (transformer terminal 4/5/B8/B7/A5/A9) are 0

 

[Paul Birkeland]

I would hypothesize that you have accidentally cut one of the power transformer wires leaving power transformer terminals 1 and 2.

You'll have to look pretty carefully for them, they wrap around the base of the terminal a few times, then disappear under the black transformer bobbin tape. 

 

[captain widwiki]

The power transformer wires seems ok...

 

[Paul Birkeland]

The upper wire in that photo looks severed to me.

 

[Doc B]

The thing to do is measure across the two terminals to see if it reads open

 

[captain widwiki]

Problem solved ! I've check again everything and I think the fuse wasn't in the right place... I feel so stupid.
But now i've another problem... There is a background noise in the left channel after a few seconds when I turn the amp on. This noise do not vary (but when i touch the tubes it can increase or produce other noises) and I can hear it at low volume or when the music is calm.

Also when the volume is all way down and I slightly increase, the music is only on the left channel (with the noise) and than when I increase again sound becomes in stereo... It may be different problem.

I thinking about resoldering some joints but which ones in particular ?

 

[JamieMcC]

Also when the volume is all way down and I slightly increase, the music is only on the left channel (with the noise) and than when I increase again sound becomes in stereo

There is a sticky note on this in the Crack FAQ section

 

[captain widwiki]

ok thanks... any advice for the other problem ?