Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Jsin on December 31, 2019, 11:40:09 AM
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All done - very excited. All tests “seemed†right and within range, but once hooked up (and when music plays all seems well and better than that even) but noticed that of the 6080 is touched even slightly/lightly I get a loud static-like POP through the headphones.
Something loose? Something touching that shouldn’t be? It seems all good as long as nothing touches it, but that doesn’t seem so 100% as it should.
All advice and pathways appreciated.
Josh
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That is a symptom of a loose connection or one that just isn't all the way soldered. I would reheat all of your solder joints.
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Will do! Also - and am hoping this is a symptom of the same issue(s) but now only right channel working.....
Uggh. Thought I’d reached the mountaintop.
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A channel that doesn't work usually comes with voltages that are incorrect.
All of this is likely due to solder joints.
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I’ve got a nice little project to kick off the New Year!
Thanks for taking the time to reply!
Happy New Year.
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I think I’ve made matters worse. I went back in and re-soldered where it looked like it needed it and clipped and trimmed some wires that were a little long, then did the resistance test and everything checked out then did the voltage test and didn’t get the results I had hoped for. Went back to do the resistance test again hit a spark at terminal 20 and haven’t been able to get this thing to power up sense. Replaced a fuse I replaced the fuse, and no glow.
I think it was only half broken before, and now I’ve taken it all the way.
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Did you have it powered up when repeating the resistance tests?
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No. Tubes out, unplugged.
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You should post some pictures of the build.
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Is the replacement fuse blowing? Is it installed in the proper spot on the fuse holder?
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Actually / yes / 1A fuse has blown each time - probably right when I plug in/turn on.
Just checked every solder (as best I can) and did resistance test and all numbers were good for that. Hope we can find a path to wellness here... should I post some pics?
J
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Yes, new pics are good. It's likely that you have two metal leads now touching that shouldn't, and that's blowing the fuse. A common place that this could happen would be where the UF4007 diodes are located.
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Here you go. Hope you see something!
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You need to get your solder joints much, much hotter. Many of them have not flowed out. If you have an adjustable solder station, crank it all the way up. If you have a non adjustable iron, hold it onto the joints until the solder liquefies, then flows into the joints.
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Really? Oy. All of them? Should I/can I redo every one?
Would too cool soldering point back to the fuses blowing?
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Cold solder joints can make the fuse blow.
Do as PB said.
Heat every solder joint till it's flowing (this can take a while), add just a touch of solder (to get the flux) and then keep the iron on that joint for 5-10 sec extra.
Let it cool slowly (don't blow at it).
When soldering, always wear safety glasses.
Redo resistance checks, post the out of line ones here. If all ok. Do voltage checks and post here.
Edit: What solder are you using?
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Thanks! I was obviously being much too timid about heat etc.
Am using 60/40 Rosin Core Solder (flux 1.8%)
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Okay - just made best attempt at reheating and flowing the solder joints everywhere.
Resistance test was all good EXCEPT FOR 20 - instead of 0 I get rapidly moving and fluctuating readings - seems to shift and change when I touch different areas of the terminal - but never reach my 0.2 or 0.3 as hoped/expected.
Might I have blown one of those tiny 0047 resistors that links into 20L?
All help so appreciated. Close doesn’t give me the cigar, and yet - junk I’m close.
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Wait - weird but now I can get my 0 reading on 20, but not if I move the lead around at all on the tab - is that the sign of a cold/bad solder? If so, on a couple of them the ohm reading changes a bit depending on where I place the lead on the tab (maybe clean read on tab and not so clean if touching a solder point)
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There could be a few things going on here. When you use solder, there is flux inside it that flows out when the solder melts with the intention of cleaning the terminal so it can be well soldered. This flux is a poor conductor, so if you touch your probe on flux, you may not get a proper 0 ohm resistance reading. If this is the case, you may find that the tinned lead of the capacitor that hooks to that terminal is an easier place to measure a resistance reliably.
The other option is that the solder hasn't flowed all the way. When this happens, that flux flows out to clean everything, but without enough heat the flux will stay put around all the leads and the terminal strip hole, so you'll get a flaky joint. It sounds like you're getting the hang of all of this, so if there's any doubt about this, some extra heat will help flow the solder all the way and move the flux to the outside of the joint.
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Thanks!!!
So, should I take one more run at re-heating a few of these that act a little funky? Or, since I do get the right readings when I am a little more intentional about where I place the lead - should I go ahead with the voltage testing?
J
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If the cap lead at terminal 20 gives you a consistent 0 and that's the only joint doing that, you could try a voltage check.
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Ok. All was good with the ohms. Tubes glowed (though one half of smaller tube seemed dimmer than the other) but no leds were lit underneath. The voltage test did not give any expected numbers.
I went back and reheated some joints - passed the ohm test - plugged it in to test voltage, no tubes glowing and a blown fuse just from turning on.
Think I keep moving myself backwards somehow.
— high maintenance
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What numbers did the voltage checks give? Actually knowing what they are could point us in the direction of your problem.
What value are you using for the fuse? In the absence of a more solid understanding of why your amp is blowing fuses, you may want to go to a 3A fuse. This will allow whatever is ailing your amp to get a bit hotter and make itself obvious. I don't normally recommend this procedure right off the bat, but other than the soldering issues from your first set of photos, everything is in its place and it's quite obvious that you followed the directions well, so this may be a necessary risk to take.
The one thing I can see is one of the UF4007 diodes on the outside of the 6 lug strip. If one diode is backwards, that would cause just about all of these issues.
If one half of the 12AU7 isn't glowing at all, that would be the solder joint on A4/A5 not functioning well. One side not glowing as brightly is more than likely just a production variation in the 12AU7 itself.
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Thanks Paul.
I gave it one more cycle of searching and re-soldering. Ensured the 4007s were all banded where they should be, checked ohms, and then turning it on blew the fuse again.
I can grab some heftier fuses later or tomorrow, but what exactly will I be looking for if those keep it running - how will it show me the problem?
Thanks again for all the attention. Am determined to get this back to where I started at least...
J
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Components that get hot will discolor, and that will tell you where to look. In the meantime, can you post some fresh build photos for us to look over?
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Sounds like I'll be looking to break something - that I know I can do...
Here's some pics of the build with some - hopefully - better attention paid to soldering.
-- might feel better about where I'm at if I hadn't been listening to music through this on Tuesday night --
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Could I see the terminal strip with terminals 17-22? Terminal 19 looks like it has a lead sticking through it that needs to be trimmed off.
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Here are both sides. I think you are seeing the wire needing trimming on 20L... but I can't figure how to get in there. Could that be causing an issue of this magnitude?
BTW - ran and got some 3A fuses. What's the process? plug it in - see what discolors - unplug - post?
-- J
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I would say that 20L is not soldered.
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You were right - soldered now.
So - do I proceed like maybe that fixed things?
Resistance test - glow test (no fuse blow) - voltage test?
<<update>> did ohm test, passed. Put tubes in, new 1A fuse, plugged it in, turned it on, and blew the fuse....
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You'll have to try the 3A fuse and see what sizzles.
If you have more 1A fuses, you can try powering the amp up with no tubes. I'm 99% certain that your fuse will still blow, but it's another test that could be performed.
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Will try the 1A fuse without tubes first - and if it still blows I’ll throw the 3A in and see. Should the 3A test be done with the tubes in?
Thanks.
J
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Sure, go ahead and have them in for the 3A test.
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That lead poking out at 19 could definitely be shorting the HV winding. Please do trim that first before running the 3A fuse.
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Do you mean the lead at 20L that is pointing down toward the base plate?
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This is what I see that could be a short that would blow the fuse immediately if those two pieces of metal are touching, or could move around and touch each other.
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SUCCESS!!!
I crimped that wire right to the board, resoldered the LEDs and a couple of other dull looking spots, did an ohm test then - moment of truth - 1A fuse and the tubes glowed. Flipped it over and both LEDs lit! Voltage test was spot on.
Just listened to Kind Of Blue on my Stein 6xx and it sounded magical!!!
1,000 thanks for all the help. Very excited to listen for awhile and then take a run at Speedball.
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I have a related question regarding a popping noise I have experienced in my new BHC build twice now with two different tubes. Both times the tubes worked fine for 5-10 mins and then I saw a bright white "spark" inside the tube. The first time this happened was with a WE 421a and the spark stayed in the same position on the plate. Both times the white sparks were accompanied by LOUD popping noises, IIRC only out of the right channel. At first I thought this might be a bad tube as I had tried 5-6 other output tubes with no issue before these... but after the 2nd time it happened with a different tube that had been tested as a good tube by the seller, I got suspicious it could be the amp.
I re-inspected the wiring and noticed that the octal socket wiring had moved a bit due to tube flex (and poor judgment on my part) so that two of the octal socket bare wires were VERY close to touching between pins 2 & 3. I am wondering if those wires were close enough to touching that this would explain the white spark on the plate accompanied by LOUD popping?
I've rewired the pin 2 & 3 wires so they are definitely not going to touch. I also reflowed a few solder joints at the same time, including the grounds for the headphone output. So far I've run both of the tubes I experienced issues with for 25+ mins each with no sparks/popping. I have PTSD from wearing my headphones when the popping happened, so I want to get your input on whether or not the issue I experienced sounds like faulty wiring that has now been fixed, OR if it could still infact be bad tubes that spark/pop very intermittently. I would hate to get rid of nice tubes that are perfectly fine. I have heard about tubes "arcing" but don't know if the issues I'm having sound like arcing.
Attaching a pic of the "white spark" glowing on the right plate of the WE421a. It was pretty bright (camera did not capture the brightness very well). Thanks in advance!
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It would be hard to say without seeing how close the wires were before, but if pins 2 and 3 on the octal socket touch, that's not a good situation!