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Trace Elliot V4 help !!

#21
Sean B said:
Would be great if new EM84 tube would fix problem. They are cheap, would a faulty one cause no sound ?
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not sure. I assumed it was a rectifier which would be VERY important to the signal path, but apparently it isn't one....so now I'm not sure. IME with big tube heads, if the amp turns on, that means the transformers are good as are the fuses. No sound usually means it's time for a re-tube....
 
#22
bassdoubler said:
that link doesn't really show me anything but I just looked up some other stuff on the EM84....what a crazy tube! I've never seen that before....what is it actually doing? It looks VERY similar to the rectifier tubes in other amps I have but I guess it isn't one....
Click to expand...

It is an indicator tube, a linear display version of the old "magic eye" tuning indicators.
 
#24
B-string said:
EM84 is NOT a rectifier tube Invalid Link Removed

Here is the schematic I found http://www.google.com/imgres?imgurl...TOMUeH0I4W4qAG3y4GYCA&ved=0CFEQ9QEwBQ&dur=848.
Marshall spec'ed the same on their imports with some 6L6GC US/EL34 Europe.
Click to expand...

Wow. Hard to imagine this thing putting out anywhere near the same amount of power with EL34s....MAYBE with the KT77s it could get a little closer....but maybe it's possible the higher voltage over there affects them differently?
 
#25
Sean B said:
I guess I'll pop a new EM84 in there when I can get one, and if that doesn't solve it she's going in for tech help which hopefully is just replacing the elusive third fuse.
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Are you sure all your 12AX7s are good? I mean, being that you have SEVEN there's a very good chance one is bad which will result in either no sound or incredibly low volume distortion. I wouldn't worry about the fuses if the amp is turning on successfully. But either way, the third fuse is IN the base of the piece that you put the plug into the amp. You have to click it in and slide it out, revealing a fuse!
 
#26
The only other thing I can think of is a blown speaker, but I doubt that it's an Emi Legend fairly new and I never have it anywhere near dimed but you never know, will test it tomorrow and see. The other preamp tubes are good for sure i spent hours taking them out and testing them in my little superchamp today, and like I said the power tubes are new.
 
#28
just because they light up does NOT mean they're necessarily good....but if you've tested them and they're all good then maybe you're right. But they can still be getting voltage and lighting up despite a disconnect inside them somewhere....could also be a faulty tube SOCKET! And all the tubes may be great....I also once had an issue with a dying power tube that I didn't realize was happening because they were all still lighting up....

But a blown speaker would still result in sound, just very BAD sound haha....I have to assume one of the tubes is bad.
 
#30
Never seen one before either, they used to use them in old radios to let you know your'e getting optimum signal from what I read online today. Going to have to take it in I think, could be a tube socket, ruling out the speaker based on what you said, at least I can tell a tech what I have tried. Thanks for all the help, I'll let you know what transpires. Have to turn in soon, work tomorrow :hmm:
 
#32
B-string said:
Don't know if it is even in the signal path?

BTW a speaker can burn out and not make any sound after.
Click to expand...

hmm interesting....this is just the first time I'm ever seeing an EM84 tube so I automatically assumed it served some kind of rectifier purpose....but perhaps it's just to show level and look cool?

And you're right, a speaker can burn out but you think it's old enough or seen enough action for that to happen? I have Ampeg cabs from the mid 60s to early 70s with all the original speakers that still sound great....but a blown speaker usually results in sound, just really crappy distorted sound....if there's a way of unplugging the V4 head from the cab and sending a different amps signal through it, I think you'll get your answer if it's the speaker or not!
 
#34
B-string said:
I would imagine it is a "cool" factor? Somewhere I have a schematic for a switchable VU/Headroom display built on EM84s. :)
BTW a KT77 is basically a EL34. KT66/6L6GC/5881, KT77/EL34/6CA7, KT88/6550 (new variants are KT90, KT100 and KT120).
Click to expand...

woah, that's pretty cool....

and I know it's in the similar family, but I was always under the impression that KT tubes receive more voltage or something along those lines. I certainly noticed a difference in headroom when I changed my 6550s out for KT88s in my V6....I'd love to hear what 6 x KT120s can do! :D:bassist:
 
#36
I have the V4 MkII head and the Em84 from my impression shows input level into the amp, the more you drive the amp the more the two green strips get compressed together, it looks fantastic and the first time i fired up the amp i was blown away with how cool the Em84 looked.
 
#38
If the EM84 is not lighting it is indicative of a B+ problem as Jon suggested. When you changed out the output tubes did you re-bias to suit the new matched set??

May I encourage you to take the amp to a tech who knows what he is doing. It's much, much safer than trying to fix the amp yourself. You could well increase the eventual price of the repair by intervening yourself.
 
#39
Yeah I used the bias adjust and the indicator says they're good. I also located as suggested by Bassdoubler two additional fuses which are good. I'm taking it to a tech as B string suggested, thanks for all the input, if I have to shell out a few quid so be it. It is a great amp, and has worked trouble free for a long while, so worth the repair cost. If nothing else at least I know a few more things about it including the location of the two slide out fuses under the ac input. Would never had thought of that, thanks guys...
 

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