Loud Pop In Right Channel Followed By No Sound [resolved]

[Colonl_Charisma]

Hi Everyone,

I just finished my very first Crack build (no speedball upgrade yet). After turning the amp on with my headphones plugged in I heard a distinct pop come from the right channel of my HD600s. Instead of turning the system off and investigating I put my headphones on and played a song and heard music in both channels which was followed by another pop in the right channel and no sound from the right channel. Do you guys have any thoughts about what may be causing this to occur?

All resistance and voltage checks passed prior to powering the system on for the first time, and I can repeat them and post numbers if you guys would like me to. Both LEDs at the 9-pin are glowing. I also tried cleaning up the RCA right input (there was and maybe still is some excess solder on it). If pictures are needed of any place on the amp just let me know.

I appreciate the help!

*My HD600s are fine. I plugged them into my solid-state amp, and the sound in both channels was normal.

[Tom-s]

This could be a problem with your ground path.
Check the connections on the headphone jack (i'd reflow all). And reflow all (black wire) ground connections.
Redo resistance and voltage checks.
Start crack first time without headphones plugged in. Do the 10s start up test to see if voltages at the jack don't climb too high. Don't know if this last step is still in the newer revisions of the manual (was there in 2013 with my Crack).

[Deluk]

Had this happen once not long after my build. Turned out that one end of an led wasn't making proper contact, touching but not soldered. Easy fix.
Also check capacitor connections.

[Colonl_Charisma]

Thank you Deluk and Tom-S! I will try both solutions probably tomorrow (no time today), and I will post back here regarding the success.

The 10s start up test at the jack is not included in the updated manual. Would you mind telling me exactly how to do it? This is something that seems worth checking.

I appreciate the help!

[Paul Birkeland]

The ten second start-up test is no longer valid with the current version of the Crack because we have wired the jack to short out that voltage during power up when no headphones are plugged in.

You could definitely post some build photos, my money would be on solder joints that aren't solid making intermittent connections.

[Colonl_Charisma]

Thanks Paul! That is good to know about the 10s test. I'll post some pictures tomorrow when I can get to my Crack.

[Colonl_Charisma]

I touched up some joints, and I actually discovered that I had failed to solder a joint. However, I am now failing my voltage checks.

I passed all resistance checks. The only voltage check I failed was terminal 7. I am getting 0.00 on my meter. Resistance was 2.8 ohms at terminal 7. Any idea what could be the issue?

[Colonl_Charisma]

Voltage numbers after retouching some joints and adding solder to 5L (this is the terminal joint that I forgot to solder):

Terminal 1 = 79 V
T. 2 = 195 V
T. 3 = 0 V
T. 4 = 195 V
T. 5 = 84 V
T. 6 = 0 V
T. 7 = 0 V
T. 8 = 0 V
T. 9 = 117 V
T. 10 = 0 V

I've also posted some pictures of Terminal 7 and my headphone jack.

[Paul Birkeland]

There are other things that can cause 0V at terminal 7 than just terminal 7 itself. 

How is the DC resistance at terminal 7?  What number does it actually give you?

Can you post some less zoomed in photos of the whole build?

[Doc B.]

I'll just say that this is the first time ever here that someone was told their close up photos were too tight. 

[Colonl_Charisma]

Hi Paul and Doc B,

I appreciate all of the help! Doc, that is very funny that my pics were too zoomed haha. I do want to say this project has been very enjoyable, and I know troubleshooting is part of the process.

Paul, my DC resistance at terminal 7 measured 2.9K ohms when I performed my last resistance check last night.

I have attached a number of photos of my build including an overhead shot that encompasses the entire build. I included shots of my 9-pin, 8-pin, and various angles of the build. Let me know if you need a shot at a specific angle.

All the best!

[Paul Birkeland]

Your solder joint at A5 could definitely cause some problems.

Otherwise, things that would make terminal 7 0V:

B1 and terminal 5 are connected by a wire and should have the same DC voltage.  If they don't, that could be a problem.  The wire at B1 could be wrapped around the tube socket contact and crimped around it.  All your connections should be crimped on the terminals/socket pins if possible.

Either end of the 3K resistor between terminal 3 and 7 not being well connected would cause this issue.  Resistance checks should catch that.

A backwards cap at 6/7 would cause 0V at 7, but that's not what's going on here.

Miswiring the connection that goes from 6 to the headphone jack and instead sending it from 7 to the headphone jack will make 0V at terminal 7.  It will also do so much more damage that it can't be what's going on.

The wire from 7 to B3 could be broken or not well connected.  B3 should show the same DC resistance that 7 does, could you double check that?

[Colonl_Charisma]

Hi Paul,

A5 was definitely an issue. I re-soldered the joint, and afterwards got a voltage reading of 101V at terminal 7. I passed all voltage checks this time. I also passed all resistance checks prior to doing my voltage checks. Terminal 7 and B3 had the same resistance of 2.9K ohms.

However, I am still getting a loud pop from my headphone's right channel followed by no sound after ~10s past powering the system. Left channel sounds great though! Haha.

UPDATE: After getting the pop I decided to see if my system could pass all resistance and voltage checks. Resistance checks I passed (T7 and B3 measured 2.9K in resistance too), but I failed my voltage check at terminal 7 again. It is reading 0V. I thought this might be some useful info. LEDs are still working and tubes are glowing.

[Paul Birkeland]

What are all the voltages?

I suspect you just have other solder joints that aren't 100%.  You could likely reflow them all in under an hour. 

[Colonl_Charisma]

Hi Paul,

I re-touched my solder joints and went through the resistance checks and voltage checks. I passed them all!

Here are my resistances and voltages per my multimeter:
T1 = * ohms, 75 V
T2 = * ohms, 175 V
T3 = 0 ohms, 0 V
T4 = * ohms, 175 V
T5 = * ohms, 79 V
T6 = 0 ohms, 0 V
T7 = 2.8K ohms, 102 V
T8 = 0 ohms, 0 V
T9 = 2.9K ohms, 117 V
T10 = 0 ohms, 0 V
T12 = 0 ohms
T13 = * ohms
T14 = 0 ohms
T20 = 0 ohms
T22 = 0 ohms
B3 = 2.8K ohms
B6 = 2.9K ohms
RCA Center Pin Right = 95.4K ohms, Left = 96.1K ohms
Ground Tab = 0 ohms (both left & right)

I am going to power the system on. Will update regarding the result.

UPDATE: Upon powering on the system the pop occurred again. However, this time I noticed that a blue charge occurred inside the GE 6080 tube triggering the audible pop from the headphones. I should note that I am not wearing the headphones when I power the system on. I was paying close attention to the tubes this time to see if I saw anything, and the blue charge and pop occurred right when the 6080 tube began to glow (few seconds after powering it on). I unplugged my headphones and gear after powering off the system. I turned the system back on with no gear attached to it, and the blue charge occurred in the middle of the 6080 tube. Hopefully, this is some useful information!