Do NOT put the Main Audio Ground on the Main Smoothing Capacitors.
That RED dot MUST be moved off the smoothing caps Zero Volts link.
Disconnect from power.
Set DMM to resistance, preferably 199.9 ohms.
Measure the resistance across the jFET drain load {resistor||VR}.
It should read near zero ohms. Adjust the VR and see the effect it has. Set the VR so that you read Zero ohms.
Now repeat for the other jFET drain load. Set to zero ohms.
Now you can power up via the bulb tester. Take measurements to prove that you have wired it all up correctly.
Report back.
Eh. As drawn It works fine, is usually quiet, and many commercial amps are built that way.
There is some thought that it can possible interfere with the input ground, but very rarely does the input return (ground) connect directly to the PSU ground. And in some cases when it does, it can be very quiet indeed.
Anyway, the concept of 'Main Audio Ground' is possibly a good one and so I kindly invite you to illustrate, not just explain, the concept for others to see, and very firmly request that you do not just jump in and YELL at members with the above quote (or similar) without any supporting information.
Building PD Board F5. Have not applied power. One board shows 49 ohms between V+ and Circuit ground. The other board does not. The answer as to what to check is going to hurt my brain. Oh, well, here goes. I'm going to hit the reply button. It hurts already. At least I have two boards to compare. Thanks. Answer like you are speaking to a slowish kindergartener. Thanks again.
It's not clear where you are. Have you gone step by step in the process in post#2 of this thread?
It starts: "Here is where I left it today -- the left amp channel is wired and finished."
In case you haven't seen it, there is another version of a guide HERE as well as other good references. Download the first item for an alternate description/process.
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I'm hosed. I have two PD F5 boards. Stuffed. They differ. They shouldn't. One has 49ohms between V+ and circuit ground, the other identical stuffed board does not have continuity. They are the same. They are not behaving the same. I have never applied power to them, nor do I intend to as long as one of them is irregular.How to tell what's broken? Time to compare the two. Yes, I've read all the stuff. 
I'll try and not get frustrated and stick them in the basement for another 3 years, unfinished.
I'll try and not get frustrated and stick them in the basement for another 3 years, unfinished.
I think I have a mosfet issue. Three of the 4 show 49 ohms between gate and source while in circuit, one of the fqa12p20 has no continuity between g and s (in circuit). Sounds like I either have 1 dead bug or three (whichever situation, continuity or no continuity is desirable), or I could be jumping to conclusions. I suppose the difference could be further upstream.
Take heart - take your time. These guys will get your amp singing if you give them enough information - including those photos 6L6 requested.
I realized, (i think), that it was just the state the mosfets were in. I powered it up, and all is well. I can bias it at will, however, I'll be biasing it a bit low until I supplement the heat sinks. It's amazing the amount of heat those mosfets can create. But y'all knew that. Next step, hooking up some cheapo speakers. Excellent.
So much better than another three year solitary confinement sentence to the basement.
Mac based music server, (30,000 songs or so), Aikido Tube pre or Pass B1 or ModWright Tube pre (long on pre-amps), Maggie 1.6s. Next projects involve repair work on a Krell KSA80B, and two Classe DR-9 power amps. Building an amp gives me more confidence to tackle those repairs.
I want to make a Salas Shunt power supply for the B1. It already sounds so good.
I want to make a Salas Shunt power supply for the B1. It already sounds so good.
