[FIXED] Deluxe Reverb: Bad 120 cycle hum and possible low B+ (edited with voltages)

Edit:

The issue was a silly one, but I left out/overlooked the jumper that connects the first filter cap negative to power ground. Embarrassed, but happy it's fixed!

Hi All,

Well, I have my deluxe reverb built and while the general guitar tone is nice, I am having some vexing issues I cannot seem to trace. I am sure I did something wrong, but at this point and after some advice from more experienced folks, still have not tracked it down.

The situation is this:

Voltages look reasonable going in to the Rectifer and Heaters. I am getting 360VAC at pins 4 and 6 (each to ground) on the GZ34. I am getting around 3.5vac from each pilot light lug to ground. Also getting 3.5vac from each heater pin (4/5 or 9 on preamp tubes) on the tubes to ground.

The issue I am seeing is that on Pin 8 of the Gz34, the voltage seems lower than it should be, as in 400v without B+ switched on. Once B+ is switched on, it drops to 335vdc. Then the B+ nodes are:

0: 335

1: 335

2: 331

3: 263

4: 220

This seems low, but when I look at the 6V6 data sheet, those are all within range.

Voltage at standby switch and both ends of choke is 335.

Here are the 6V6 readings:

w/out power tubes:

P: 402

S: 400

G: -32

w/ power tubes:

P: 332

S: 330

G: -32

Currently, I have it biased at 9ma, which I know is low, but if I bring that up the plate voltage then drops to around 315 v at around 12ma. I can only take it up to 17ma before the bias pot tops out and the voltage drops below 300v.

The other symptoms are a very pervasive 120 cycle hum, and when a note on the guitar rings out (especially on a lower open string) it fizzes badly as the note decays.

I checked all continuity between points and verified component values before I fired it up the first time. I also have verified correct value resistors and cap polarity in the filtering section. I pulled the PCB up and checked for any long solder legs, or shorts or loose connections. I've chopsticked all over the place and cannot seem to isolate the hum to any specific connection. I have inspected the tube sockets and soldering/connections. Reflowed some joints. Moved some wires around, all to no avail.

You can see/hear a of the sound here, and the note decay issue. I will also upload some photos of the power and filtering section for visual reference, My PT has a center tap for the heaters, so I am not running the virtual center tap as shown in the layout (although I did originally not realize I was doubling the ground reference).

Anyhow, I am at my wits end today. I've probably spent a good 8 - 12 hours trying to resolve this. Any outside perspective or tips are welcome. This is my first push/pull amp, and the biggest build I've done so far, so I am sure I have done something wrong. I'm fairly close to taking it in to my amp tech's much more capable hands, but, you know, pride and wanting to find the issue myself and all that. 😂

Thanks in advance.