Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Klots on January 14, 2015, 05:40:07 AM
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Hello,
Going to make a separate thread for my problem (have talked about this in some other threads).
Problem: Output tube starts squealing after a little listening (transfers into the right channel only). This happens random and it does not matter if I change the output tube or drive tube or both (RCA 6080, GE 6AS7GA, TS 5998/ RCA 12au7, Siemens E80CC). Nothing also changed when I changed output caps for film type and added bypass caps to them.
Thing how to get rid of it: Tap on the large tube or pull out and insert again the headphone plug. But the squeal returns after a few seconds or minutes.
When I tap on the aluminum panel there is weird distortion in the right channel.
Tried: Made sure that every component on the aluminum panel is correctly attached and checked every solder joint. Did the bamboo stick test and changed the power switch (stock one went bad after getting too much soldering heat). Did all the measurements also. And I will post them here:
Resistances:
1) *
2) *
3 ) 0 ohm
4) *
5) *
6) 2.48K ohm
7) 2.92K ohm
8 ) 0 ohm
9) 2.94K ohm
10) 2.48K ohm
12) 0
14) 0
20) 0
22) 0
B3) 2.92K ohm
B6) 2.94K ohm
RCA Jacks:
Ground lug 0 ohm
Center pin 49.2K/ 49.2K ohm
Powerswitch ON: 0.5 ohm
Transformator 1-2: 45.9 ohm
Voltages:
1) 79V
2) 171V
3) 0
4) 171V
5) 81V
6) 0
7) 103V
8 ) 0
9) 105V
10) 0
11) 0
12) 0
13) 172V
14) 0
15) 192V
20) 0
21) 214V
A1) 81V
A2) 0
A4) 0
A5) 0
A6) 79V
A7) 0
A9) 0
B1) 79V
B2) 172V
B3) 103V
B4) 80V
B5) 172V
B6) 105V
B7) 0
B8) 0
L-N voltage: 247V
Transformator 1-2: 242V
Transformator 4-5: 5.7V
Transformator 6-7: 167V
Transformator 9-10: 167V
I soo love my Crack but this squeal thing won't let me enjoy music. I will include some pics too. If anyone have some questions or ideas what to test or measure etc. then please share :)
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You have a loose wire or flaky solder joint somewhere in your Crack. The best step at this juncture is to reheat all your solder joints.
-PB
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6U seems to lack solder, thats also the right channel, also 10U doesn t look so good
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Lot of wires just poked thru and soldered without being bent around the terminal. That makes for a less structurally sound connection. I'd suggest reflowing, and adding just a tiny bit of solder when you do.
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Looks to me you have a lot of joints that need more solder. Don't be afraid to put a lot, make sure it covers the tips completely. After soldering, be sure to cut the excess wires poking out for a nice clean finish. Good luck!
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I have resoldered every joint about 5-6 times before and nothing changed. But I think I will take everything apart and install everything again. Purchased some new wire too (should arrive in two weeks). It started to squeal one day and I did nothing before that.
How can unplugging/plugging in headphones take that squeal away when it is a solder joint? If I tap the aluminum panel the distorted sound appreas, but it does not affect the squeal in any way.
Is there a possibility that a transformator or output cap(s) are starting this noise somehow?
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I actually rebuilt my crack twice before I was happy with soldering and such.
I allow myself to recommend this series of howto videos:
https://www.google.no/url?sa=t&rct=j&q=&esrc=s&frm=1&source=video&cd=1&cad=rja&uact=8&ved=0CBwQFjAA&url=https%3A%2F%2Fwww.youtube.com%2Fplaylist%3Flist%3DPL926EC0F1F93C1837&ei=3EqRVMCLK4iAzAPihIHYDw&usg=AFQjCNF7e7HY_m6OAs50V0CcJ_A0dpmwoQ&bvm=bv.82001339,d.bGQ
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Will check these out. Thanks!
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Did the Crack squeal prior to the Teflon bypasses going in?
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Did the Crack squeal prior to the Teflon bypasses going in?
It squealed even with the electrolytics....caps did not change anything
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How can unplugging/plugging in headphones take that squeal away when it is a solder joint? If I tap the aluminum panel the distorted sound appreas, but it does not affect the squeal in any way.
This is because something is loose, and when you tap the plate or jar it by plugging/unplugging headphones, you are restoring the loose connection.
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This is because something is loose, and when you tap the plate or jar it by plugging/unplugging headphones, you are restoring the loose connection.
Then tapping the plate should also restore connection and the squeal should go away, but it doesn't. Only things that help are tapping the output tube and plugging in headphone jack (I can do it very slowly and gently, but it still takes the squeal away).
I ordered new power supply caps too. So when I rebuild my crack I will change all wires and these three caps. Then I will make sure every joint is correctly soldered and if there is still squeal there is something else wrong. When I built the crack a year ago I did not have any massive experience with soldering, but it still worked perfectly after first try (no squeal or other noise, every measurement was correct etc). And now just one day it started to squeal. It is quite a mystery to me :) Of course I will check for any loose connection over and over again, but haven't found one.
What if it is not loose connection that is causing the squeal?
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If only tapping the output tube cancels out the squeal, then I would start by really looking hard at the octal socket.
Replacing the power supply capacitors will not remedy this issue, and I wouldn't move forward with that plan until the root issue is determined.
Your statement that the right channel is the channel which squeals suggests that the power supply is most likely not the problem, but rather a cold solder joint or loose connection on the right channel.
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I re-soldered all joints again today and it got better, so when new wire arrives I will make sure every connection is perfect and hope it will eliminate the sqeal. Thanks for your help! :D I will let you know when wires are replaced etc.
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Changed all wires. Changed the 2.49k resistors in headphone socket and 270ohm 5W resistors too, because they are so cheap. Still the same squeal. I bought some 220uf 250V caps for power supply and uf4007 too. Will change those too. Thought about replacing valab volume pot and headphone socket also.
Little edit to the first post: the squeal does not transfer to headphones. I was mistaken. Tried this yesterday (left the amp in one room and went to other room with headphones).
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Parts don't squeal.
Loose connections, wiring mistakes, and iffy tube socket to tube pin connections can cause squeals.