Speedball problem?

[karl.sandqvist]

Hello,

First build, first post for me. I've had the crack kit for a couple of months but just recently built it.

I did the build without the SB first with the only upgrades being a stepped attenuator and some nice RCA plugs. Took my time and loved every minute of it! There were zero problems, resistance and voltages check all close to spot on. The amp was dead quiet even at full volume before SB.

Listened a couple of days while assembling the SB boards. Installed the SB in one night, not so patient this time, eager to get on with listening. Did the voltage checks, evetything ok, phew!

Plugged in my HD600, what? A loud hum present, hum stays constant regardless of volume level. Quickly discovered that wiggling the 9 pin tube gives scratches and loud pops. After a pop the sound is amazing and hum gone. Then it pops again, hum and bad sound back.

I've reflowed all SB wire connection points but the problem remains. If I tilt the 9 pin tube it will make a loud pop and the sound is good again, hum gone. When I let go of the tube, It will pop again and the hum is back.

I've not reflowed the 9 pin socket connections because  I had no problems with it before SB. For esthetic reasons I've installed the socket from underneath. Now I'm starting to suspect the socket as the culprit. Should there be a crack (lol) in the socket? I've tried to capture it in the pictures.

Btw, all LEDs glow and voltages are all close to the manual values.

Any held would be very appreciated!

Br, Karl

[karl.sandqvist]

I cannot upload photos directly from my iPad. Will try to attach them on my work computer tomorrow.

/Karl

[Paul Birkeland]

I've reflowed all SB wire connection points but the problem remains. If I tilt the 9 pin tube it will make a loud pop and the sound is good again, hum gone. When I let go of the tube, It will pop again and the hum is back.

You very likely have a loose connection on the 9 pin socket, or on the other end of a wire that connects to the 9 pin socket.

-PB

[karl.sandqvist]

Thanks PB!

I just reflowed all 9 pins and the other ends of the wires. Mounted the PCB:s , put in the tubes and plugged in.

Noticed the LEDs on the smaller PCB next to the pot did not light up. Neither did the led between A3 and center. The voltages were 0 on the board with dark LEDs. Voltages ok on the PCB with working LEDs. B+ voltage ok on the big board but 0 voltage only 60V.

When reflowing the pins I did make a note to self that I might have fried that A3 led. Can a fried led at A3 cause these symptoms?

I do have spare LEDs so changing it is no biggie, just too tired to do it now. They are fiddly to work with, those LEDs!

Thankful for any help!

/Karl

[Paul Birkeland]

Can you post the actual voltages that you have now? Terminals 1, 2, 4, and 5 are the only voltages you really need to measure.

[karl.sandqvist]

Yes, here they are:

1: 78V
2:175V
4:174V
5:0V

Can it be just a faulty led at A3?

Br, Karl

[Paul Birkeland]

Try reheating the center leg of the MJE350 feeding terminal 5.

Generally, a bad LED should cause terminal 5 to read roughly the same as terminal 4.

[karl.sandqvist]

Done!

Nothing changed.

Terminal 5 still cold (0V).

Any ideas? Thanks so much for your help!

/Karl

[Doc B.]

Maybe a wire is broken inside the insulation. Check the continuity of the wires coming off the big board, from one end to the other.

[karl.sandqvist]

Thanks PB and Doc!

Indeed I found that the red wire between 4U and the small board was broken right at the solder joint at 4U!

Fixed it, plugged in, YES! All LEDs lit up! Voltage checks ok, on to listening!

Well, back to square one but not quite? The hum is there and sound is bad but it's now consistent and does not change when I move the input tube around.

But now I noticed another thing. While unplugging the headphone I get a jolt.

There's an old thread describing someone getting a jolt while unplugging his HD800. Shall I follow the advice given there?

/Karl

[Paul Birkeland]

Yes, you likely have a bad solder joint where the black wires meet at the headphone jack.

[karl.sandqvist]

Thanks, I will look into this on Monday, don't have time before that.

Your help is really appreciated! Will report back when I've checked my ground connections!

/Karl

[karl.sandqvist]

OK, I'm back at the soldering station .

Resoldered the black wires at the jack and at T12. Plugged in, let it warm up a bit, tried the jack for any shocks... Yes, problem gone!

Close but no cigar yet   there's still hum present but it has decreased in volume and moving around either the tubes, headphone jack or pot or just tapping on the plate does not affect the hum.

Oh, the sound quality is impressive when turning up the volume a bit. It's really frustrating to be so close to a fully working amp. Any ideas? Chopstick method next?

/Karl

[karl.sandqvist]

I'm a bit puzzled by the fact that my build prior SB was flawless from the start and dead silent and now I'm having multiple issues  .

/Karl

[Paul Birkeland]

I would suggest continuing to investigate solder joints.  You can plug a very cheap pair of headphones into the Crack, then poke at each component and connection with a wood chopstick while it's running to listen for changes.

These problems existed before your Speedball was installed, but it took flipping the plate over and moving a few things around to disturb them enough to become problems.