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PostPosted: Mon, Oct 30, 2017 3:37pm 
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Hack

Joined: Sat, Feb 20, 2016 6:23pm
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Hey guys

I have a strange problem with my VH4 from 2001, I checked the bias tonight, and the second tube from the left doesn't have any current going through it.
So I checked the Bias and it only showed current from a single tube (around 35 mA) and the other pair was at 61 mA, which I guess is fine.
I thought it was a bad tube, or the fuse which was bad. I changed both and it still didn't have any current running through it. It just lights up but that is it.

I must point out that the amp sounds FINE, it has no crackles and plays awesome otherwise, but I guess it is only 75 watt :P

So my question is what can be the problem in this case? I can take more pictures and details if needed.

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PostPosted: Mon, Oct 30, 2017 4:03pm 
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Journeyman NOOB
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Sounds like a bad screen resistor.

The one your red arrow is pointing at in your pic should be the bad one, looks like it too.

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PostPosted: Mon, Oct 30, 2017 4:30pm 
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Hack

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Thanks for the answer! I think you're 100% correct.

I am not a tech-savvy guy, so do you know which 1KO resistor I should buy?

Thanks!


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PostPosted: Mon, Oct 30, 2017 6:30pm 
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Plank Cranker Wanker
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Location: Rockin a LP in to a Diezel
If you are 100% sure it's not simply a bad tube... I'd make sure there is no carbon build up in that tube socket. Also is that epoxy/silicone on/around the wire running between the power tube sockets?

The screen resistor value would be 1K Ohm 5W. The brand Xicon is commonly used here.

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PostPosted: Mon, Oct 30, 2017 7:09pm 
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Hack

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100% not a bad tube. I tried 3 different working ones, which worked in the other positions but that single one.

I'll check the carbon build up.

Yes there is some kind of epoxy on the wire/sockets.

Do you have a link to the resistor, I just want to make sure I get the right on haha!


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PostPosted: Tue, Oct 31, 2017 11:30am 
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Journeyman NOOB
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https://www.amazon.com/Ceramic-Cement-Power-Resistor-Watts/dp/B0087ZDIZ4

This should work.

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PostPosted: Tue, Oct 31, 2017 11:35am 
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Hack

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rickenbacker198 wrote:


Thanks man!


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PostPosted: Tue, Oct 31, 2017 9:53pm 
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Immortal Rock God
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Location: I'm BACK in da saddle again.... I'M BAAAACK!!!!
www.tubesandmore.com will also be a good resource if you're in N. America.

Keep us posted :thumbsup:

Unkle Mo

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PostPosted: Tue, Oct 31, 2017 10:20pm 
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Hack

Joined: Sat, Feb 20, 2016 6:23pm
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Ventura wrote:
http://www.tubesandmore.com will also be a good resource if you're in N. America.

Keep us posted :thumbsup:

Unkle Mo


I am located in Denmark, so I just ordered some Vitrohm 1ko 5w from Germany. Should arrive in 2-3 days!

I'll make an update when they arrive :thumbsup:


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PostPosted: Wed, Nov 01, 2017 3:16am 
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Diezel Amplification
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Well done


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PostPosted: Wed, Nov 08, 2017 10:17am 
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Hack

Joined: Sat, Feb 20, 2016 6:23pm
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Hey guys

A quick update!

I soldered the new resistor on today and it worked! Current through all tubes again.
I checked the carbon buildup, but the socket was all clean.

I guess it was just a bad resistor after 16 years of use. It broke in two just after I replaced it. But it is all fixed now.
Thanks for your fast inputs to my problem! :D

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PostPosted: Tue, Nov 14, 2017 5:46am 
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Diezel Amplification
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The resistor was broken by a bad tube.


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