Finished BUT octal tube POPS when touched/jiggled [resolved]

[Jsin]

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

 

[Paul Birkeland]

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.

 

[Jsin]

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.

 

[Paul Birkeland]

A channel that doesn't work usually comes with voltages that are incorrect.

All of this is likely due to solder joints.

 

[Jsin]

I’ve got a nice little project to kick off the New Year!
Thanks for taking the time to reply!
Happy New Year.

 

[Jsin]

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.

 

[kgoss]

Did you have it powered up when repeating the resistance tests? 

 

[Jsin]

No. Tubes out, unplugged.

 

[Jameson]

You should post some pictures of the build.

 

[Paul Birkeland]

Is the replacement fuse blowing?  Is it installed in the proper spot on the fuse holder? 

 

[Jsin]

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

 

[Paul Birkeland]

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.

 

[Jsin]

Here you go. Hope you see something!

 

[Paul Birkeland]

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.

 

[Jsin]

Really? Oy. All of them? Should I/can I redo every one?
Would too cool soldering point back to the fuses blowing?

 

[Tom-s]

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?

 

[Jsin]

Thanks! I was obviously being much too timid about heat etc.
Am using 60/40 Rosin Core Solder (flux 1.8%)

 

[Jsin]

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.

 

[Jsin]

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)

 

[Paul Birkeland]

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.