It looks like it's not. PSU ground pin is 30V above chassis ground...
Dang, you're quick.
Measure to the lug on the chassis floor. I added a snippet above likely after you read it to do a quick resistance check between all pins within and between the jacks.
What's the black probe connected to? Why? ..... if the red wire "works"... then that connects pin 1 to the chassis. There should be 0V between pin 1 and the chassis pretty much by definition.
Measure to the lug on the chassis floor. I added a snippet above likely after you read it to do a quick resistance check between all pins within and between the jacks.
What's the black probe connected to? Why? ..... if the red wire "works"... then that connects pin 1 to the chassis. There should be 0V between pin 1 and the chassis pretty much by definition.
Best place for takeoff is the back junction jumper of the PSU that you have soldered. But before you do that, I would measure resistance between PSU gnd (mentioned jumper) and chassis, heck, even a voltage DC and AC measurement can’t hurt. Can’t hurt to also measure resistance between MOSFET middle pins and chassis too (amp off), but it looks like you have mounted the fets before soldering them so that test I expect to end up in Mohms or the high K’s.
........ or - open circuit (Ol), if you didn't connect these two in any way
which you must
VAC between PSU and chassis is indeed 30. DC voltage is effectively 0. Resistance between middle pin of MOSFET and chassis is open.
Maybe... maybe not...
IF it were connected to the chassis... and IF pin 1 was connected to the chassis, then there would be 0V between pin 1 and the chassis.
Anyway... you've got too many people typing to you all at once. I'll bow out.
But... that's why I advised taking the measurements to the mains earth / safety ground lug on the chassis floor also... if mains earth is to be your ground reference... start there.
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So decided to do some more testing so want to verify what I'm seeing looks correct before hooking up another $2k interface
The teal colored trace is measurement between XLR pins as labeled in picture file name. The purple trace is measurement at speaker terminals.... Most of these are capturing power off. The Single on a smaller time scale is power on... I'm guessing that since what I'm connecting to produces +24dBU signals I should be safe with this.... I'm not too worried about the speaker thump and realize the measurements unloaded aren't completely valid...
The teal colored trace is measurement between XLR pins as labeled in picture file name. The purple trace is measurement at speaker terminals.... Most of these are capturing power off. The Single on a smaller time scale is power on... I'm guessing that since what I'm connecting to produces +24dBU signals I should be safe with this.... I'm not too worried about the speaker thump and realize the measurements unloaded aren't completely valid...Attachments
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Hi everyone - I need to come here for confession, shaming, and encouragement. I started my build around 2 years ago, got as far as having the power supply finished/tested, and a new job, cross country move, etc. distracted me. I just saw the announcement of the new Jzm, and that finally gave me the encouragement to get this project across the finish line.
Hello,
I know this has been addressed before, but I had an idea for inverting the Jfet input stage in order to allow the use of LSK170 or LSK389 (in my case I plan to use LSK489). I've seen versions where the N channel Jfets were the opposite of the orientation I propose, but I'm not used to seeing negative voltage applied to the drain and positive to the source. I just want to know if this makes sense &/or if there are things I could change. Also I inverted Q2 (CCS).
Thanks for your time.
I know this has been addressed before, but I had an idea for inverting the Jfet input stage in order to allow the use of LSK170 or LSK389 (in my case I plan to use LSK489). I've seen versions where the N channel Jfets were the opposite of the orientation I propose, but I'm not used to seeing negative voltage applied to the drain and positive to the source. I just want to know if this makes sense &/or if there are things I could change. Also I inverted Q2 (CCS).
Thanks for your time.
reasons why that isn't going to work are on too low/basic level to be clever/useful to explain in one or few posts in thread
I mean, question shows that you're lacking basic knowledge of basic parts operation; when you learn basics, you'll have explanation to today's question ..... and then you'll be able to think further;
There are numerous sources ( books, on-line) so learning is easy
We all were in same boat - really wishing to write a love poem, even before learned entire alphabet