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 Post subject: impedance switch / O.T.
PostPosted: Sat Dec 31, 2011 6:16 pm 
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Joined: Mon Sep 05, 2011 8:51 pm
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Location: NW Ohio, U.S.A.
Well I finally reached the point of powering up my amp. I followed the procedure specified in the manual and everything checked out fine until I got to the step of plugging in a cable and trying to induce some hum by touching it. I got nothing. I got on here and did as much research as I could. This thread (http://www.trinityamps.com/phpbb/viewtopic.php?f=1&t=3095) gave me some worries.

So I checked into the impedance switch. I had it wired right, so I tried hooking the 8 ohm tap directly to the outputs and still nothing. Any ideas of what to check for?

Another thing I noted was I had continuity between all the different ohm taps when they were wired to the switch, it didn't matter where the selector was, I got continuity between all the pins on the switch in any combination, A-1, A-2, A-3, 1-2, 1-3... is this supposed to be that way? Is it possible my O.T. is fried?

Thanks and Happy New Year All,
-Josh


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PostPosted: Mon Jan 02, 2012 7:06 pm 
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The DC resistance of the OT secondary is a very low value. So you will always appear to have continuity between the secondary taps.

Do you get any hum or hiss at all from the amp while it's running?

Your next step is to carefully measure voltages at the pins of all the tubes, while the amp is running with a speaker plugged in and not on Standby.

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PostPosted: Tue Jan 03, 2012 11:25 pm 
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Joined: Mon Sep 05, 2011 8:51 pm
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Location: NW Ohio, U.S.A.
Well I am an idiot, I completely missed wiring up the cathodes on the EL84's. There is a reason why it says to use a highlighter to mark off the schematic as you double check everything. Easy to overlook something if you don't mark it as done. It's at least making noise now and the voltages check out okay. Thanks so much for the help.
-Josh


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PostPosted: Thu Jan 05, 2012 4:55 pm 
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Location: Canada
Easy to miss but a critical piece! Glad it's working now!

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Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps


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PostPosted: Mon Jan 09, 2012 1:36 pm 
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Joined: Mon Sep 05, 2011 8:51 pm
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Location: NW Ohio, U.S.A.
Especially easy to miss since I bought the kit "used" and the board came with all the components and wires soldered up (except the one...) All I did was verified all the components were correct and then connect the wires up. I assumed all the wires were there and it bit me in the butt. Lesson learned.

I've built it, I've rocked it, now it's time to box it! I'll post some pics when I get it done but don't hold yer breath, I'm SLOW...
-Josh


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PostPosted: Mon Jan 09, 2012 2:24 pm 
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JPRIZZ wrote:
I've built it, I've rocked it ...


And how was it?

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PostPosted: Mon Feb 13, 2012 10:59 pm 
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Location: NW Ohio, U.S.A.
It was rockin'! I've still got to build the head cab and speaker cab, so I ran it into my Marshall valve sate combo, even through that it was still great. I can't wait to get those cabs done to really open it up and let it shine.


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