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PostPosted: 19 Oct 2009, 12:06 
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Hi Dan, the resistor? circled in red is what we were wondering about. Looks like it goes from the PCB to the chassis.


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PostPosted: 19 Oct 2009, 18:03 
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Ok,

I am not sure but it looks like Mr. Millet has used a "ground lift" ???
so there is a 5-10 Ohm resistor between audio ground the chassis, to prevent ground loops etc.
Having said that the pic is a little blurry....



-Dan

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PostPosted: 20 Oct 2009, 12:04 
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Yeah, it is not clear so I will email Mr. Millett and ask.
Cheers

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PostPosted: 21 Oct 2009, 12:25 
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Pete wrote back very quickly and here is his response regarding grounding of the PCB (and the two resistors seen in the photo 3 posts back).

Quote:
It's rather hard to see, but the "RECT CT" pin on the PCB is wired to the center tap of the HV winding on the power transformer. There is also a wire from the CT (at the transformer) to a ground lug that is located right next to the white power resistor (I think the black wire). This lug is the chassis ground point. Wires (green) also run from there to the (-) side of the output jacks (and also, on this particular power transformer, a shield/ground pin).

The resistors were an afterthought. The B+ was too high using the transformers I had, so one of the resistors (the white one) is in series with the choke, and the brown one is connected from B+ to GND (big bleeder resistor). This is just to drop the B+. You'll also note I removed the first filter cap so the way I built it it's actually a choke-input filter.

Pete

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PostPosted: 21 Oct 2009, 16:42 
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Wow Lucky you asked !!

Thanks Gio/Pete

-Dan

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PostPosted: 25 Oct 2009, 17:29 
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I've completed one amp. However I have an ugly "static" on the output. Music can be easily heard, but the static is really bad. The noise does not change with volume increase. It sounds exactly like noise one would hear while tuning an old AM radio.

Is it possible that my 3" wires from the pcb to the chassis mount sockets are acting as antennae?

Thanks, Greg


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PostPosted: 25 Oct 2009, 18:37 
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HI Greg,

Do you have a pic of the setup? Perhaps we can help you out.

PS - yes it is possible

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PostPosted: 25 Oct 2009, 20:07 
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Hey Greg, a couple more items to check.
- When you power off, does the noise go away immediately or does it fade away?
- What happens when you touch the chassis, pot, RCA jack?
- Is there noise with no input connected?
- Does the noise change if you change the source?

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PostPosted: 26 Oct 2009, 04:04 
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Thanks Gio!

I'll have to do some testing with a different source and with the source disconnected. I'm also going to swap out the tubes. I have some old ones in for start up. Maybe one of those has an issue.

Cheers, Greg


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PostPosted: 03 Nov 2009, 06:58 
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hi all , im marco from Milano -Italy , ive purchased two years ago , a pair of pcb millett uniamp , but after the assembly (with 5998 as final) :worried: ......
now ive a quartet of 6L6 , someone can help me to make "sound" from those amps?

sorry 4 my english ..... :eek:

tnx

marco


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