Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: chavac on July 31, 2013, 05:19:24 PM
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Hopefully someone can help me out here. Spent the last two nights putting my crack together and finally finished, but it seems a couple of my measurements on the resistance check don't check out. They would be 12->22 (reading infinite) and 12->nine pin center pin (which reads 0). I've look at and resoldered almost every connection looking for a cold solder but no dice so far. All of the other measurements seem pretty spot on. Any suggestions? Thanks.
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The center pin of the 9 pin socket should read zero.
So terminals 12-22 all read roughly infinity?
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Ah ok, my manual says 90-100k
12
13 slowly creeps up to ~7.8
14 0
15 slowly towards infinity
16 0
17 infinity
18 ~2.4
19 ~2.4
20 0
21 creeps to 7
22 infinite/no movement
Everything below that and all the B terminals tested OK
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Ah, the center pin of the RCA jack is 0 Ohms? That would indicate a short on the jack, look for metal or solder connecting the center solder cup to the outside of the jack.
12 - you gave no number?
13 - 7.8 Ohms, 7.8K Ohms, or 7.8 MOhms?
14 - this is supposed to be zero (as indicated in the maunal)
15 - climing to infinity is good
16 - this is supposed to be zero (as indicated in the maunal)
17 - climbing to infinity is good
18-19 - 0 this means you probably have a short in the diode bridge. Look for two metal UF-4007 leads touching each other, but going to different terminals.
21 - this confirms the short in the diode bridge
22 - this terminal is grounded, it should be at zero (how is T16?)
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Oh my mistake about the center pin, I completely misread that and missed where is said RCA center pin.
And I didn't include twelve because I've been using that as the ground.
From what I can tell 16 is zero and grounded. One thing I didn't note, I lost the buss wire for my kit and substituted de-sheathed excess wire (don't know if that makes a difference).
7.8k ohms
and from what I can tell the diodes only touch where the enter the same terminal
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It is possible that one of the diodes are reversed. Double and triple check the diodes. Then get someone else to check. This is one of the most often mistakes assembling the kit.
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I've looked at the amp for about 15 minutes this morning desperately trying to find an error. I did realize that the lower LED's direction was reversed. However it broke when I attempted to remove and reverse it from the center pin. Could that potentially be the cause? It still gives the same resistance now without the led attached (new one on order from mouser). Otherwise the diodes appear to be correct. On the inside 18L -> 21L with stripe towards 21, and and 20L->18L with white towards 18. The outside is 20L->19L with stripe towards 19, and 19L->21L with stripe towards 21.
Also noticed I had one smaller round lockwasher left over (one went to transfer screw closest to safety ground, other to nine pin). Don't know how that would affect anything.
Btw thanks so much for the help. This is my first DIY amp so not familiar at all with troubleshooting.
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Yes the LEDs have definite direction and that one needed to be fixed. You can shoot an email to [email protected] and get a replacement sent. Get that part installed, redo the measurements and let us know if you still have readings that are off.
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Alright so dropped in the new LED with correct orietation and got these resistances (with 12 as ground)
11: 0
13: slowly to~7.9k
14: 0
15: slowly to7k
16: 0
17: 0
18: 2.4k
19: 2.4k
20: 0
21: 6.7k
22: infinite
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Is the black wire crossing over the power transformer connecting to terminal 21 or terminal 20? I suspect you have a miswire here.
-PB
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No, it's spanning 14u to 20u, the parrallel resistor abve it is 15u-21u
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Oops, I was off by a terminal.
So the issue is 22 not being 0. That's not enough to not fire it up and recheck voltages.
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Ok i'll check the voltages. Haven't actually even turned the thing on yet.
And thanks again tfor the help.
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hmm only the smaller tube lights up
and only one led
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Those aren't exactly voltages...
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Ok this is what I got:
1 110
2 110
3 0
4 110
5 50
6 0
7 0
8 0
9 0
10 0
11 0
12 (negative probe)
13 110
14 0
15 110
16 0
17 0
18 40
19 40
20 0
21 120
22 0
A1 50
A2 0
A3 0
A4 0
A5 0
A6 0
A7 0
A8 0
A9 0
B1 110
B2 110
B3 0
B4 48
B5 110
B6 0
B7 0
B8 0
There was a pop when I tested 21, left a small black mark on the solder but nothing otherwise
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Do both halves of the 12AU7 glow?
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Yes
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Alright, well, the most likely issue is the unlit diode on the 12AU7 socket (I'm assuming there's no Speedball installed).
One or both ends is not making a proper connection, which is allowing no current to flow (and thus terminal 5 isn't droping down as it should).
I'd carefully examine that diode and its solder joints.
-PB
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Correct there is no speedball. Resolder the LED's joints, no change. Replaced with one of the extras I had ordered and it lit up. Some changes to the voltages:
1 50
2 110
3 0
4 110
5 45
6 0
7 0
8 0
9 0
10 0
11 0
12 (negative probe)
13 110
14 0
15 0
16 0
17 0
18 40
19 40
20 0
21 120
22 0
A1 50
A2 0
A3 0
A4 0
A5 0
A6 50
A7 0
A8 0
A9 0
B1 50
B2 110
B3 0
B4 48
B5 110
B6 0
B7 0
B8 0
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Well done, your 12AU7 is now operating properly, both LED's must be lit at this point.
Now, the 6080 is being presented with a reasonable operating parameter, but it it sucking current like crazy!
Can you check that the 3K resistors are in fact 3.0K?
Next, triple check that the 100uF/160V caps are connected properly (striped sides out), and that the wires running to the headphone jack leave the outboard terminals (6 and 10) on the terminal strip? If those wires were connected to 7/9, you would experience these issues (until the 2.49K resistors cooked).
Let me know if these suggestions are helpful, and especially if they are not.
-PB
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Hmm. Headphone wires appear to be correct to 10 and 6. AFAIK they two resistors are 3k (xicon p 10w 3k j). And rechecked solder on all caps and location/orientation, all seem correct. Resoldered all four jointed, still no 6080 when I fire it up
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Ah, that's right, you had mentioned that the 6080 doesn't glow?
Does there happen to be white residue in the tube instead of silver residue?
Are you 100% sure the socket is properly oriented?
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Hmm. Yeah the 6080 doesn't lightup. Which part of the tube would have residue? I don't see any. And the way it's shaped it only fits one way. One thing I just noticed is it looks like the new led I just put in burnt out already/doesn't light up anymore.
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I think Paul meant is the socket itself properly oriented, not the tube within the socket. I believe the residue would form on the top of the tube, but Paul will correct me if I'm wrong.
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Adam is spot on, if the tube had leaked, the silver coating on the tube would begin to turn white.
Check the socket orientation, if it's off you could create some interesting problems.
-PB
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Double checked the orientation and appears to be correct with the slot facing the vent. I don't see any white residue at the top, just the silver cap. There does appear to be a metallic sheen around the bottom of the silver cap portion, but nothing I would call white.
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Can you post a pic of the octal socket on your Crack? (including the adjacent terminal strip)
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https://www.head-fi.org/g/i/903101/default/sort/display_order/
https://www.head-fi.org/g/i/903102/default/sort/display_order/
https://www.head-fi.org/g/i/903103/default/sort/display_order/
They were too large for the forum, so I just uploaded them onto my headfi gallery. Hope that's OK. Added one of the whole board in case I'm missing something obvious
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Can you remove the 6080 and repeat your voltage checks? (your build looks very good BTW)
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Will the burnt out led matter?
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Not particuarly, I'm looking for the voltages at 1/5 to pop up.
-PB
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Almost identical to the first set I gave earlier, except A6 has a reading as it did in the second set. The led blinks on when I check it too.
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Ooo, this is good info, can you pop out the 12AU7 and repeat?
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Ok here's with neither tube in
1 115
2 115
3 0
4 115
5 115
6 0
7 0
8 0
9 0
10 0
11 0
12 (negative probe)
13 115
14 0
15 115
16 0
17 0
18 45
19 45
20 0
21 115
22 0
A1 115
A2 0
A3 0
A4 0
A5 0
A6 115
A7 0
A8 0
A9 0
B1 115
B2 115
B3 0
B4 115
B5 115
B6 0
B7 0
B8 0
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Hmm, there is still a power supply issue, could you pop some photos up of that? There are a fair number of potential sources, but a photo should make it pretty clear.
-PB
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https://www.head-fi.org/g/i/903127/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/
https://www.head-fi.org/g/i/903128/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/
https://www.head-fi.org/g/i/903129/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/
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Can I see the area around the diode bridge?
Is the ground lug by the IEC entry socket soldered?
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The buss wire is solder in the middle to the lug.
https://www.head-fi.org/g/i/903138/default/sort/display_order/
https://www.head-fi.org/g/i/903139/default/sort/display_order/
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Alright, with no tubes in, what is the AC voltage between 18 and 19?
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Zero
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With the power turned on? Are you 100% sure?
(It's not possible to have 0V AC across these terminals and any DC voltage anywhere else in the amplifier)
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Yeah it's zero. Does that mean my transformer is DOA? I can actually see the needle just barely twitch when I touch the probe, but it still settles at zero. I get voltages everywhere else
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Is your meter set to measure AC volts when you take the measurement?
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Was it supposed to be? I've been using it set to 500 DC...
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Yes, to measure AC volts you want to use the AC volts setting on the meter.
Chalk up another for Doc, PB.
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Wow I feel dumb. I just saw in the instructions above the voltages in the instructions it said dc closest to 400... my bad.
And apparently you are VERY good because my 6080 just turned on for the first time, despite not changing anything from last night. The following are with both tubes in (AC500)
1 160
2 175
3 0
4 175
5 80
6 0
7 160
8 0
9 100
10 0
11 0
12 (negative probe)
13 175
14 0
15 200
16 0
17 0
18 85
19 85
20 0
21 230
22 0
A1 85
A2 0
A3 0
A4 0
A5 0
A6 0
A7 0
A8 0
A9 0
B1 156
B2 175
B3 156
B4 85
B5 175
B6 105
B7 0
B8 0
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Have you reflowed all of you solder joints?
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More or less yes. I haven't systematically gone through them 1 by 1 but I've resoldered almost all at least once, many several times. I'll keep at it though.
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Alright so went through them 1 by 1, only thing I really found was B6->T1 looked a little sketchy. Redid that and several others... and bam. New voltages all approx 10-16% from the guide, everything lights up. Thanks so much DocB and PB, one of the reasons I trusted myself to make this in the first place was because I heard about bottlehead's amazing forums/support if anything went wrong. Now on to listening!
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Yes the keyword is all the solder joints. I don't understand why so many builders are so stubborn about reheating every joint. It takes like ten minutes. I couldn't count the number of customer amps I "repaired" over the years that I simply reheated all the joints on.
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I think this thread is the best example I've seen yet of how outstanding the BH customer service is, how timely responses are provided, and how well troubleshooting from afar can work.
Congrats to chavac for not giving up and for successfully completing your build!
Best regards,
Adam