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Posted by Romy the Cat on
09-04-2017
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I was telling somewhere that in case you have built Super
Milq then you need to label everything. My Milq has test point at plates of the
first tube, the bias and plates of second tube. It means 3 test points per channel,
time 6 channels it makes 18 hole in the amp that provide voltages. Well, it is
14 test points as 2 channels are single stage but I have 2 extra test point to measure
both sides of bias supply and 2 test point… that I clearly do not remember what
they do. One of them gives 12V, I presume hat it is serves voltage and one is
60V … I have no idea where it comes
from. Plus it has 9 attenuators and adjustable resistors and only god remember
where it what. If would be nice if I was
positioning all test points and adjustments in some kind of clustered logical manner.
I did not and I put them exactly where it would make a shorter path and less vulnerable
from any type of induced noise. I just wish I have a map of it!
A case to point. Yesterday I turned the amps and was
listening something as I felt that there is some kind of unpleasant asymmetry
in sound. Soon I discovered that a Fundamental channel on my right side and
silent. The Plate of the single stage
amp has voltage, the bias is perfect but there is no signal is coming out.
I looked at the schismatic and identified that probably the
filter got shot.
http://www.goodsoundclub.com/Site_Images/6-Chennal_Melquiades_DSET_Amplifier_Rev3.jpg
It is a channel D and the only way if the tube operates properly
and the signal is not coming out is if the filtering cap to grout of the filtering
coil got shored. So, disconnected everything, flipped the amp and begin to test
the things. I know that you guys do not know what it means but trust me – it a
whole revolution in house to do it. This thing is heavy, demanding and it is
not 15 mind job. In few hours I was convinced that the damn thing works fine,
drove the signal and the tube was amplifying. The only blame was the OPT went
down, something that I would say VERY unlikely. Then I look at the schismatic again
and recognized that the channel has an attenuator in a OPT secondary. The fan part was that remember myself fine dialing
the damn Fundamental channel but I do not remember where the attenuator is. It
took for me an hour to look in and out of the amp to realize where the
attenuator was. I clearly see that it was placed in very non-intuitive location,
I wish the idiot who built the amp would consider all of it during the design
phase.
So, the moral of this story: label or map it religiously.
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