Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: smallmany on February 09, 2014, 07:34:09 PM
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Resistance
1 0
2 0
4 0
5 0
VDC
1 0
2 0
4 0
5 0
7 65
9 62
13 198
15 210
A1 0.1
A3 0.6
A6 0.1
B1 0.1
B3 64.3
B4 0.1
B6 61.4
Off my multimeter, the 9pin socket should have zero voltage but both my tubes filaments glow. The sound comes out but is really quiet. There is a loud constant hum at any volume. Both the LEDs are not glowing.
Any ideas? Help
tl;dr No voltage at 9 pin socket. Low voltage at 8 pin socket. But there is sound just not very audible/distorted + constant hum
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Having 0 Ohms at 1-5 means don't turn the amplifier on....
Since terminals at 1-5 are directly wired to other terminals, you should have other resistances that are off.
Can you post a full list of these?
Is there any way you can upload pics of your build?
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Welp, I was missing the wire from B2 to 2L.
So I solved the resistance problem but the LED connected to A8 is not lighting up.
I can't remember all but terminal 1 had voltage of around 150v
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is the LED important or is it just a indictation that voltage is running through
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Again, please post your resistances and do not turn the amp on...
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Is mis-wiring the culprit for my blown LED at A8? If not, what may be the reason? The other LED was functioning
Thanks
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How is the LED blown? Did you hear it snap, did the leads break off, etc?
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smallmany,
Paul, Caucasian Blackplate, knows this amp as well as anyone alive. You should be answering his questions rather than asking new questions. Paul can walk you through fixing this.
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The LED at A8 would not light up. Thinking that it was a cold joint, I reheated the solder, and the lead melted out of the LED.
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You can e-mail [email protected] and we can send you some additional LED's.
I would encourage you, however, to post all your resistances before turning this amp on again.
If the resistance check is good, then move on to powering up the amp.
For an issue like an LED not lighting, that is certainly what we are here for. More often than not, this actually has nothing to do with the LED itself, but manifests from elsewhere in the circuit.
-PB
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Once the replacement arrives, I'll be sure to give you an update of the readings
Thanks
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After soldering the new LED, everything checked out almost perfect. The center seems a bit off when i listen to it, i feel like the center is a bit off to the right. Hoping it is just the tubes burning in.
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Also, the tube next to the transformer gets so hot I could cook my eggs on it.
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Also, the tube next to the transformer gets so hot I could cook my eggs on it.
That's good, it is working exactly the way it is supposed to.
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I noticed that when i increase the volume, the right side is louder than the left , but is fine at low-medium volume.
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resistance of 600k ohm on terminal 13 , it is above the 270k but it varies with ohmmeters right?
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The difference may be due to the fact that the tubes haven't burned in yet. Just enjoy some music for a while and see if the imbalance gets better as the tubes break in.
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resistance of 600k ohm on terminal 13 , it is above the 270k but it varies with ohmmeters right?
Yes indeed.
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Since tubes degrade faster the hotter it gets, is it possible to add a heat sink to deviate the heat away?
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Since tubes degrade faster the hotter it gets, is it possible to add a heat sink to deviate the heat away?
There is a range where a given tube will operate well. If you go too high, you will indeed shorten the life of the tube, if you go too low, you get poor performance out of the tube. We are running the 6080 at about 25% of its maximum dissipation rating, so there is nothing to be concerned about here.
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What areas of the crack controls the sound quality of the left audio? Im still not hearing any changes to the recessed/less prominant left side of the headphone. I know that it is not my source/headphone because without the amp it is perfectly balanced, and switching the rca connector reverses the sound quality so it must be the amp itself
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and switching the rca connector reverses the sound quality so it must be the amp itself
So switching the cables that come into the amp moves the recessed quality to the other channel?
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Yes :-\ the lesser stellar sound stays on to same channel.
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Yes :-\ the lesser stellar sound stays on to same channel.
That would be a "no", the stellar sound does not switch channels.
How are your voltages?
If this doesn't clear up in 50-100 hours of operation, I would look at rewetting any solder joints that don't look shiny.
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Have you solved the problem yet? I have similar problems.
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Not yet, but i'll be taking PB's advice and rewet some joints. Will post an update if it improves performance.
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If you can please post any voltages that are out of spec we might be able to offer some more ideas about what to look for.
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ironically, I blew my fuse doing a voltage test. Once I replace those, i'll get on it Doc.
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will this fuse work
1A 250VAC
Type number:MFG
5.2mm x 20mm
interrupting current : 35 A 250VAC
miniature fuse
1 80
2 175
3 0
4 175
5 80
6 0
7 103
8 0
9 104
10 0
11 0
12 0
13 175
14 0
15 196
20 0
21 219
A1 80
A2 0
A4 0
A5 0
A6 80
A7 0
A9 0
B1 80
B2 175
B3 103
B4 80
B5 175
B6 103
B7 0
B8 0
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will it harm my headphone/amp in anyway, if i maximize the volume on the crack amp and control the volume via computer?
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It might harm the 'phones, if the computer puts out any transients (typically turn-on or turn-off but sometimes when switching sources).
It will probably damage the resolution, since digital level control usually involves a loss of digital resolution.
But what do I know? Nothing, when it comes to current digital practice!
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Interesting info
Is there a way to improve crossfeed in the crack? I have noticed a lot of channel separation and left/right panning, and it's starting to get fatiguing..
Only happens during crack use 8)
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Crossfeed should be relatively easy to implement on the digital side (on your computer).
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Idk if this affects the sound, but the screw between the 9 pin socket and terminals 1-5 stick out more than the other side.
And there is the #6 lockwasher, I was only able to use 1 out of the 2. The second one is in my drawer, was I supposed to use both?
Also even with daily usage, the sound has yet to reach full dynamic range on the left side. I've rewetted every joint and it is all smooth and shiny, resistance and voltages all check out. What is wrong with my amp
Any suggestions are welcome zzz
Can provide pictures if it will help resolve my issue
thanks
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Idk if this affects the sound, but the screw between the 9 pin socket and terminals 1-5 stick out more than the other side.
And there is the #6 lockwasher, I was only able to use 1 out of the 2. The second one is in my drawer, was I supposed to use both?
The front screw is supposed to be shorter, as part of the Speedball mounts to a longer standoff on the rear screw. Did you have an extra #6 lock washer included with your kit, or did you intentionally leave one out?
Also even with daily usage, the sound has yet to reach full dynamic range on the left side. I've rewetted every joint and it is all smooth and shiny, resistance and voltages all check out. What is wrong with my amp
I would still guess that it is a solder joint, or that there may be an issue with one of the RCA jacks. What resistance do you get from pin to shell on each RCA jack? (This measurement will be between 90 and 110K, if one side is 90K and one side is 110K, this is meaningless and should be ignored)
If none of that helps, I have another test in mind that should be helpful for you.
-PB
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When i received the package, there were 2 #6 lockwashers, but to my knowledge from the manual, it is only used once. RCA pins read 98-97k for both jacks
I would love to try your test, I am willing to try anything.
Just curious, when you mention the measurements, are you implying reading the meter while moving the tester probes across the wire and jack? because I do get wild reading when I slide the probe around as I try to read it. I get a constant reading of 97-98k if i keep it still.
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Yes, both #6 lock washers go on the 9 pin socket to keep the nuts in place.
OK, the next step of diagnosis is to download a 60 Hz tone, then play it through your Crack while taking voltage measurements.
You will want to measure AC volts between the chassis and:
Outer top pot lug
Outer bottom pot lug
Middle top pot lug (turn the control all the way up)
Middle bottom pot lug (turn the control all the way up)
If you have the grounding mod on the headphone jack, turn the level control about half way down, then plug headphones in and measure:
Terminal 6
Terminal 10
If you do not have the grounding mod on the headphone jack, you can perform this measurement with nothing plugged in.
These voltages will be in the tenths of a volt to several volts, so adjust your meter scale accordingly.
-PB
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I am getting absolutely nothing.. Uh ohh..
This is without that grounding mod you spoke of, all the tests were done without anything plugged in the headphone jack.
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You can try measuring the 60Hz tone with your meter at the interconnect. It might help to really crank the level coming out of your PC.
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I forgot to connect the pc to the amp ;D
The pot reads 1.61-1.62v
Terminal 6 reads 14.6v
Terminal 10 reads 1.83v
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I forgot to connect the pc to the amp ;D
The pot reads 1.61-1.62v
Terminal 6 reads 14.6v
Terminal 10 reads 1.83v
Woah, yeah, there's a problem there!
So all four terminals on the pot gave ~1.62V? That's a good sign.
Can you very carefully repeat the measurements, but this time measure the AC voltage at T1 and T5? Most meters should still pick up on the 60 Hz AC component and block the DC. If you see something like 12V AC, that's a valid measurement. If you see something a lot higher, then let me know and we can tweak things to get your measurements.
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T1=177.6v
T5=176.9v
Terminal 6 and 10, I must have read wrong, after doing numerous tests, T6 is on average is only 2-3 times larger than T10. i.e: T6=2v T10=.7v
Also, at maximum volume, T6 and T10 both have a reasonably close value of 15.3v.
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Well, while those voltages are sort of meter nonsense, they would suggest that the 60Hz signal is getting into the 12AU7 and being amplified properly.
This would leave a funky 6080 (which may have been damaged when run with the missing wire from B2 to 2L), or a bad solder joint on the 6080 tube, specifically the wiring to and from T9 and T10, as well as the feed from T5 to B4.
-PB
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Is there a way to test if the 6080 tube is in fact damaged?
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The easiest way would be to pop in a different 6080 and see if you get the same results.
I'd really go over those specific solder joints first.
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I've rewetted those joints but to no avail. :(
Update: I forced the pot counter clockwise, now i get no channel imbalance at low volume and the sound is even. Im contemplating whether or not the sound quality worsened or not
e
s
r
Definitely wo
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I'd see if you can source a 6080 locally. They are an incredibly common tube, and should be available at an old time TV repair or general electronics repair shop.
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Replaced the stock pot with alps blue velvet, balance issue is gone.
The stock pot drove me insane, you guys should give the option of purchasing a pot that isn't so crappy :P
Looking forward for the speedball . Thanks for those who replied, especially PB. ;D
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Replaced the stock pot with alps blue velvet, balance issue is gone.
The stock pot drove me insane, you guys should give the option of purchasing a pot that isn't so crappy :P
Please let us know if you find a high performance potentiometer at a decent price that we can be 100-1000 of at a time.
(FYI - the PEC pot that is beloved on many forums actually has poorer channel balance than the pot we use, as does the dual 100K control that you can get at Radio Shack. We also offer advice on how to add a 10 cent pair of resistors to solve the channel balance issue)
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Please let us know if you find a high performance potentiometer at a decent price that we can be 100-1000 of at a time.
http://www.tocos.com (http://www.tocos.com)