Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: pnooud on February 21, 2015, 06:20:29 AM
-
Hi,
I would like a bit of help diagnosing an issue I am having with my newly built Crack with Speedball.
I finished my crack build off last night and spent a good few hours relistening to my favourite music, it did wonders for my hd600s, the bass really came to life.
I tried it this morning and there was no sound in the red channel; after turning it off and wiggling a few cables, there was sound again; so today I have finished off my speedball install (so possibly the issue may have occurred before the speedball)
Since the speedball install I am having an issue; I get sound for about 20 seconds, but when it heats up there is a loud pop and I loose the red channel; this is repeatable by letting it cool down and turning it back on.
After the pop the voltages changes to:
1. 75.1
2. 181.4
3. 0
4. 181.9
5. 175.6 was 82 on startup
6. 0
7. 173.5 was 114 on startup
8. 0
9. 111.3
10. 0
11. 0
12. 0
13. 182.1
14. 0
15. 200
20. 0
21. 217
The LED between Socket A Centre and A8 goes out after the pop.
I have reflowed most accessible joints, but took care during the install, so suspect that a joint may not be causing it.
Any advice would be greatly welcomed, I am itching to get back to listening to my crack again, it sounded great. :)
-
A bit more info:
I thought that something must have been up with the little tube, because the issue was happening after it warmed up, so I took it out and gave it a bit a lot of a shake and put it back, for some reason it started working.
I am reluctant to put my headphones on incase I get another deafening pop; I will leave it playing for an hour or so first I think :)
-
Bad contacts are frequently results of bad solder joints.
Especially since You seem to have a good set of voltage results
From manipulating the tube and reinserting it, You should
at least resolder A1-9 and the ground.
You will find many similar situations in the Crack forum threads
-
I think I have spotted it now, I was obsessively careful not to get a dry joint, so pretty sure its not that.
I think A8 had been squashed down too close to A7 by the wires when I put the speedball in and it was shorting.
There are no loose bits in the tube, so think thats fine.
Back to some listening now :)
I will post some pics of my build once my base is done
-
This sounds really awesome. 8)
The standard crack seemed to add the power to open up the bass that the hd600s were missing; with the speed ball upgrade, it feels like your in the room with the artists.
-
Its happened again :(
Same issue right channel silent, voltage high on T5, T7
1. 77.6
2. 180.3
3. 0
4. 181.2
5. 175.4
6. 0
7. 174.1
8. 0
9. 112.6
10. 0
11. 0
12. 0
13. 181.7
14. 0
15. 200
20. 0
21. 218.9
B1. 173.9
B2. 179.9
B3. 173.0
B4. 77.2
B5. 180.2
B6. 112.2
B7. 0
B8. 0
I took off the speed ball boards and resoldered A1-9, as Strikkflypilot suggested, but I am still having the issue.
LED on A3 is on A3 measures 1.5v
LED on A8 is off, A8 measures 0 (fluctuating around -7mv)
Any advice would be great, Thanks in advance.
-
Check that the smaller transistors are in the correct holes.
If they are, the center leg of the MJE350 is somewhat reluctant to take solder properly, so hold your iron there a little longer than normal to be sure the joint flows well.
-PB
-
Thanks Caucasian Blackplate,
The top side of the centre leg of the MJE350 did look like the solder hadn't flowed all the way through from the other side, so I resoldered it from the top, unfortunately its still not fixed.
All the transistors are the correct type, and in the correct position. Both of those little boards look identical and comparing the voltages at various places around the each of boards, they are the same, except for the middle leg of the MJE350 and the Output where the voltage is high.
Any other ideas?
-
Based on the voltage values, can we say for sure its one of the little speedball boards or the tube that's causing the problem?
Is it worthwhile swapping the two speedball boards over to eliminate an issue with the board?
Is there a description of how this works somewhere that may help with fault finding?
Thanks.
-
You can swap the small boards to see if the high voltage at T5 moves to T1. High voltage from a small PC board indicates:
1. Incorrect transistors installed or incorrect orientation of MJE-350 (writing faces edge).
2. Center leg of MJE-350 has sunk too much heat from the soldering iron to be soldered properly (most common).
3. The tube is not conducting. This is not an issue that just pops up with the installation of the Speedball, it would have been an issue with the stock kit.
4. A miswire of the board ("I" solder eyelet not going to terminal 2 or 4, "O" solder eyelet not going to 1 or 5)
-PB
-
Thanks Caucasian,
I have swapped over my speedball boards and the high voltage stayed at T5
So I guess from what you are saying the problem is with the tube :(
The next day after first night of listening it didn't initially work, but after messing with the rca connections it sprung to life again, so it could have been there intermittantly from day 1.
-
I'd really be looking closely at the solder joint at A4 and A5, if that isn't solid, half the tube won't conduct.
The other possibility is a grounding issue, which would present itself as significant DC voltage at A2 or A7.
-PB
-
How about posting some images of the different terminals?
Many sharp eyes out there that might spot the culprit.
-
Thanks Both,
I will recheck those points and get some pics up tomorrow, not had time today.
-
I ordered a cheap old tube off ebay, it was delivered today so I swapped it over and I have music again :) so there must have been something wrong with the tube.
The I ordered a brimar 12au7, but I got a tube that has the brand ZaeuX on it, the guy also gave me a second tube as a free gift which is just labeled 12AU7A, with no other branding.
With the Zaeux tube, there is a little more treble, and you notice listening to a track with a busy drum section, the drums seem to have a bit more texture.
The non branded tube was a bit smoother sounding, but sounded a bit cleaner.
It would be good to know if it sounds better or worse than the original; I seem to remember the original sounding better, but that could have been the glass of single malt I had :)
Where should I go from here do you think, I am wondering will I get much more detailed sound etc spending a bit more?
Thanks everyone for your help while this was fixed it was reassuring to know that there were people willing to take the time to help me get to the bottom of it :)
-
That tube you got may be a Brimar with another company's label painted on.
If you post a photo on the tube rolling with Crack thread, we can ID it for you.
-PB
-
Posted, Thanks