LED's do not light and voltages are wrong

[ghostyjack]

I've finished my build and have done the resistance and voltage checks.

It passes the resistance checks but the voltage check are not good.

1. -0.5v
2. -0.5v
3. 0.4v
4. -0.3v
5. -0.4v
6. 0v
7. 0.4v
8. 0v
9. 0.04v
10. 0v

The tubes glow, but I can't see anything happening with the LED's, they do not appear to light up.

Reading the forum, it looks like I just need to check my joints and reflow them? Should I be looking anywhere specifically?

 

[Paul Birkeland]

I would suspect the joint where the black wires meet on the heapdhone jack as the primary suspect.

What DC voltage do you get between terminals 12 and 13?

 

[ghostyjack]

The voltage between 12 and 13 fluctuates from about 0.2v to -0.4v.

 

[Paul Birkeland]

Can you post some photos of your build?

 

[ghostyjack]

Here are some pictures for you, let me know if you need any specific areas.

 

[Paul Birkeland]

You missed a step on page 38.

The terminal 12 end of the 270K resistor looks like it might touch the screw at terminal 11, which wouldn't be helpful for noise.

 

[ghostyjack]

Page 38 was when I went to make a coffee. Though I picked up where I left off, obviously I didn't. I've now put it in.

That resistor isn't touching, close, but there is a gap. Was just the camera angle.

I've rechecked my voltages and they are all good now.

I tested it with a cheap AKG K92 as I had it lying around, I know it is a low impedance headphone, but I'm not testing it with my HD6XX. Sounded lifeless, but I assume that was to be expected.

When I disconnected the AKG, the Crack was still on, there was a very loud click. So loud I thought I'd damaged them, but they worked again when I plugged them back in. Should I expect to get this when plugging in headphones?

I've tried it (with a bit of trepidation) with HD6XX by switching it off first, plugging them in and then switching them on. Wow! Massive difference between them and the AKG's, so much more life to the music. Just sat through Holst's Planets suite, sounded fantastic.

 

[Paul Birkeland]

Be sure the middle outer lug on the headphone jack is well soldered.  I'm thinking about putting a Keurig about three feet from where I solder, so I totally get it.  No harm was done by leaving that wire out and powering the amp up. A harmful noise when plugging in your headphones will come with elevated voltages at terminals 6 and 10.  With no headphones plugged in, those should be just a few mV of DC voltage, if anything at all. 

-PB