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09-04-2017 Post does not mapped to Knowledge Tree
Romy the Cat

Boston, MA
Posts 10,075
Joined on 05-28-2004

Post #: 1
Post ID: 23384
Reply to: 23384
Label or map it religiously.
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. 
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.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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