Help With Crack, Audio Cut Out and Resistance Issues

[unowndanger]

Hi,

So I bought the crack 3 years ago, and set everything up. Pretty frequently I'd get some hissing or white noise and audio drops with the crack, and I chalked it up to poor soldering on my part. I went inside a couple times to reflow things and check resistances, and everything seemed to work.

Last night, I was only getting audio out of the left earcup. I first tested the cables the headphones directly into my desktop to make sure it wasn't the headphones, then tested the RCA cables with another audio source (and a different pair of cables) and I determined it wasn't that. The tubes were glowing, at least the larger of the 2 were. I didn't check the smaller one, but it was previously working.

I would plug everything back in to test, but I disconnected everything to run a resistance check and the below are my results. I'm hesitant to plug everything back in to run a voltage check until my resistances are all correct.

Terminal   Manual               My Reading
1          *                        0 Ohms
2          *                       0 Ohms
3          0 Ohms               0 Ohms
4          *                        0 Ohms
5          *                      0 Ohms
6          2.4K ohms              0 Ohms
7          2.9K ohms              2.95k ohms
8          0 Ohms               0 Ohms
9           2.9K ohms      2.9K Ohms
10           2.4K Ohms      0 Ohms
12           0 Ohms              0 Ohms
13           Will climb slowly   0 Ohms
                toward 270K Ohms   
14           0 Ohms              0 Ohms
20           0 Ohms             0 Ohms
22            0 Ohms             0 Ohms
B3           2.9k Ohms    2.95K Ohms
B6           2.9k Ohms    2.94K Ohms

I'm unsure how to proceed with trouble shooting this. I misplaced the PDF of the manual and basically scoured the forum to final a relevant resistance check table for me to add my findings to. I am attaching photos below of the soldering job as well as many photos of the entire build as close up as possible. Any and all help is appreciated.

[Paul Birkeland]

Are you 100% sure those are all zeroes and not OL?

One wire passing through the earthing lug back by the IEC power entry module isn't captured by solder.  Most of your joints look like they need a significant amount of additional solder and lots more heat. 

[unowndanger]

I will be sure to double check and report back.

Do you know if it's possible to get another copy of the manual since I misplaced my file?

Thanks!

[unowndanger]

Finally got a chance to update the readings. Here's what I got.

Terminal   Manual               My Reading
1         *                        OL
2          *                       OL
3          0 Ohms               0 Ohms
4          *                       OL
5          *                      OL
6          2.4K ohms              OL
7          2.9K ohms              2.95k ohms
8          0 Ohms               0 Ohms
9           2.9K ohms      2.9K Ohms
10           2.4K Ohms      0 Ohms
12           0 Ohms              0 Ohms
13           Will climb slowly   OL
                toward 270K Ohms   
14           0 Ohms              0 Ohms
20           0 Ohms             0 Ohms
22            0 Ohms             0.03k Ohms
B3           2.9k Ohms    2.95K Ohms
B6           2.9k Ohms    2.94K Ohms

Also, here are more photos of the soldering job at various angles: https://imgur.com/a/mZFqxDe

I'm unsure if they'll be of help, but I figured I'd add them in case they can be. I appreciate all the assistance.

[Paul Birkeland]

I see a lot of leads poking out here and there, I would go back in with your needle noise pliers and wrap them over the terminals nice and tightly, then solder between what's wrapped around the terminal and the terminal itself.

I would bet that a proper set of side cutters would help too.  The CHP-170 is what I tend to recommend and they are inexpensive.

You can contact replacementparts(at)bottlehead(dot)com and ask for an additional download for the manaul.

-PB

[unowndanger]

Sounds good. I'm gonna redo all the connections and see how that goes.

I have another question. So with desktop computers, when you shut the desktop down and go to work on the inside of it to repair or replace parts, you have to drain the power from the power supply since some residual energy is stored in there.

Is there any proper protocol in working with the BH Crack and making sure I drain any residual power that's in the unit that is stored? Or do I not need to worry about that with the Crack? Thanks!

[Thermioniclife]

There is a 270k resistor connected to terminals 12 and 13 that bleeds off the charge on the power supply filter caps when you
shut the amp off. However it is always prudent to check the caps with your meter set to dc volts and one lead clipped to ground and probe the pos lead of the 220uf caps.

[unowndanger]

Alright, so I resoldered Terminal 6 at the terminal, terminal 10 at the terminal and terminal 13. I also resoldered the IEC points that were brought up earlier.

https://imgur.com/a/pwsneit

Above are the images.

As an update, 13 climbs to 270K ohms, slowly, but it's inconsistent, sometimes it will drop out, other times it's a steady climb. Terminal 10, when there's initial contact between the red and black wires of the multi meter, provides me with a low resistance of 0.06 and then goes to 0.0 ohms. Terminal 6 remains at OL still, but sometimes 0 based on where I touch it.

Is it possible those capacitors are shot?

[Paul Birkeland]

12L and 13L look to not have sufficient solder.  Same with 10L.  So let's focus on 10L.  Bend the lead of the banded end of the capacitor up and over the terminal and crimp it onto the terminal strip, then solder to both the terminal strip and the crimped lead.  Repeat that process where you can. 

If you don't have 0 ohms at terminal 6 (assuming nothing is plugged into the 1/4" jack), then you have a loose solder joint either at 6 or at the headphone jack.

The solder joint you have at your ground tab right now looks really good.  You want solder joints that look like that everywhere in your amp.

[unowndanger]

Awesome, thank you! Now, this might be a dumb question, so I apologize, but is it okay if the solder from 10L is in contact with 10U, or should they be kept apart?

Thanks!

[Paul Birkeland]

10L and 10U are the same piece of metal, so no big deal there.

[unowndanger]

So I think I walked it one step forwards, two steps back. I resoldered Terminals 12,13,10,6, the headphone port that connects to 6 and terminals 2 and 5.

I did 2 and 5 to add more solder at your recommendation, and now terminals 1 2 4 5 have resistances. The vary. but

Terminal 5 is 150K and slowly goes up
Terminal 4 is 100k and slowly goes up
Terminal 3 is 0
Terminal 2 is 79K and slowly goes up
Terminal 1 is 100K and slowly goes up

Terminal 6 is now reading 0
Terminal 10 is now reading 0
Terminal 13 is stably going up
Terminal 12 is 0

Images here: https://imgur.com/a/2chUWdB

[Paul Birkeland]

1L is very light on solder. 

Your resistances look OK though. 

[unowndanger]

So it's okay that 1,2,4 & 5, slowly go up when in contact with the leads instead of immediately responding as OL when the leads are in contact?

So does it look like either 6L or 6U or the corresponding headphone slot need more solder?

[Paul Birkeland]

So it's okay that 1,2,4 & 5, slowly go up when in contact with the leads instead of immediately responding as OL when the leads are in contact?

From the manual:

Also, the values signified with a *
are going to vary from ohmmeter to ohmmeter because these terminals are connected to the
filter capacitors, which try to charge themselves off the battery in the meter, causing a fluctuating
reading. If the circuit is connected properly these readings will wander in the tens or hundreds of
KR or higher range. What you want to watch out for is a zero reading at one of these terminals,
which would indicate that something is mis-wired.

So does it look like either 6L or 6U or the corresponding headphone slot need more solder?

I can't see any issues from the photos you posted.