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December 07, 2021, 01:10:14 PM

Author Topic: Resistance Check L14  (Read 198 times)

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Offline Clover

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Resistance Check L14
« on: November 21, 2021, 11:11:34 AM »
I finished the connections for my S.E.X build last night and am going through the resistance checks now.  I am getting an overlimit reading on L14 and the manual says it should be 0 ohms.  I don't have anything connected to L14.  Should I run a ground to it or do I not need to worry since nothing is connected to L14?  Maybe I need to create some space between the white rectangular part and the lug?

Offline Thermioniclife

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Re: Resistance Check L14
« Reply #1 on: November 21, 2021, 12:11:09 PM »
IIRC t14 is bolted to the chassis and should show 0 ohm to ground. You are correct that nothing connects to that terminal but I would investigate why it is not at zero ohms.
Lee R.

Offline Clover

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Re: Resistance Check L14
« Reply #2 on: November 21, 2021, 02:25:42 PM »
Thanks. 

Hmm... well I might have done a poor job measuring.  I was just fiddling with it again and got it to read near 0.  If I push backwards on it, the reading jumps around a bunch but gets low near 0.  However, I need to be pushing on it to get that reading.  Is that a problem or should I just call it good and move on to voltage tests?

Offline Thermioniclife

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Re: Resistance Check L14
« Reply #3 on: November 22, 2021, 05:02:15 AM »
At that point it may be best to tighten the hardware.
Lee R.

Offline Clover

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Re: Resistance Check L14
« Reply #4 on: November 22, 2021, 09:40:40 AM »
Thanks, that makes sense now that you pointed it out to me.  Duh!

Offline Thermioniclife

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Re: Resistance Check L14
« Reply #5 on: November 22, 2021, 10:14:41 AM »
I'm glad you got it sorted out.
Lee R.

Offline Clover

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Re: Resistance Check L14
« Reply #6 on: November 22, 2021, 01:22:53 PM »
She alive.  Stole a set of cables off my sim rig and am rocking out now.  I did have a couple little shorts that I found and solved after turning it on the first time.  Feels great to have built it myself.  Thanks for the help everyone.  Tons of power for my headphones.  Way more then the Focal Elegia's need but it sounds great to me. 

I had read that a drawback to tubes was bass control but I actually find the bass noticeably clearer then before without the amp.  There is more of a hum then I expected without any music playing.  As soon as the music starts it goes right away though.  Reminds me of the sound I would get plugging in a guitar to an amp.  I guess that shows just how much I know about tube gear.  I have the C4S upgrade that I will install after I get accustomed to the sound that from my understanding will help with that hum and noise floor. 

Woo Hoo! Thanks again everyone.  Planning to get stoned as a gravel road and really dig in later tonight.
« Last Edit: November 22, 2021, 01:50:47 PM by Clover »

Offline Paul Birkeland

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Re: Resistance Check L14
« Reply #7 on: November 22, 2021, 01:58:40 PM »
I would not expect there to be any hum that you could notice, but one thing I have found is that if terminal 36 is allowed to touch the transformer screw it's next to, that can add some noise that shouldn't be there.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Clover

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Re: Resistance Check L14
« Reply #8 on: December 03, 2021, 09:27:54 PM »
I'm now getting, kind of like a ruffling mic sound out of the left ear cup from the headphones.  Not sure what is going on, it sounds like someone is taking their mic off and fussing with the mic only in the left earcup.  I had left the amp on for over a day and was letting it warm up when this started.  Easy to hear without music but can be herd with music on as well. 

I checked everything on 36 and I think it is clear of the screw for the transformer but it is fairly tight.  You think it is worth redoing that lug or does the left earcup only problem indicate something else?  Thanks.

Offline kgoss

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Re: Resistance Check L14
« Reply #9 on: December 04, 2021, 04:17:20 AM »
Try swapping the tubes to see if the noise switches sides or changes.
Ken Goss

Offline Clover

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Re: Resistance Check L14
« Reply #10 on: December 04, 2021, 10:05:07 AM »
After leaving it off overnight and swapping to tubes, everything seems to be working better then ever.  Maybe I did not have one of the tubes seated properly.  I'm not sure.  However, the little hum that I herd before when it was quite is also gone.  I thought that was just normal but I guess it was not.  Thanks again for the help.

Offline kgoss

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Re: Resistance Check L14
« Reply #11 on: December 04, 2021, 03:16:40 PM »
It is quite possible that moving the tubes made an iffy connection solid. If the problem comes back do the chopstick test with some cheap headphones.
Ken Goss

Offline Clover

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Re: Resistance Check L14
« Reply #12 on: December 04, 2021, 04:41:58 PM »
After leaving it on for a while, some static has appeared in the right earcup now.  I'm not sure what the chopstick test is, but I am guessing that since the problem showed up in the other ear after swapping the tubes that maybe I just need a new tube.

Offline Clover

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Re: Resistance Check L14
« Reply #13 on: December 04, 2021, 05:45:58 PM »
I left it on and the static got increasingly loud.  We actually herd the static coming from one earcup of the headphones from another room and came to investigate.  I think I am going to order a new pair of tubes this weekend.  Would people recommend another set of the GE tubes that came with the S.E.X 3.0 or is there a different set anyone would recommend I try if I"m buying a new set anyways?  I have never bought a set of tubes before.

Offline Paul Birkeland

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Re: Resistance Check L14
« Reply #14 on: December 04, 2021, 07:38:01 PM »
I would let the tubes cook in for a while.  Some noise from a tube that hasn't really been powered up for 60 years isn't particularly surprising.

You may also want to gently clean off the pins of the tube with a small brass brush or some 0000 steel wool (be sure there's no steel wool particles left before you plug the tube back in though!).
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man