Deluxe Reverb build has me stumped

[Duncan]

I’ve finished putting together a Deluxe Reverb build (using the Robinette layout, confirmed wiring with Fender schematic).

Voltages are all good and I have tried swapping the primaries from the output transformer.

I’ve included photos of the build and here is a link to what it sounds like, regardless of which channel I'm plugged into:

i=66p636iA4F5GzH13

https://ibb.co/q0tLXYm
https://ibb.co/JqNL0M4
https://ibb.co/84vSLKs
https://ibb.co/DbQZx9c

Does anything jump out to you?

[tubeswell]

Not pretty distortion.


From a quick glance at the build pictures, the wiring looks a little messy, and soldering iron burns on parts (e.g. the yellow styrene caps) may not be helping. Difficult to see what else may be wrong just from looking at those pictures.


Other than that, what do the voltages look like?


And any scope shots of key signal points?

[mresistor]

I don't want you to feel to badly but the soldering work in these pictures is very bad. Looks like there could be many cold solder joints. Did you wire the cathode resistors/capacitors from underneath the board? Thats really not the best way to go about it. When soldering on the turret above the wire below could fall out. Best to connect the cathode leads to the turret. You can solder a wire to the body of the turret as well as wire into the top hole and solder. I don't like the way that the cathode resistors are strapped to the huge 25uf F&T cathode bypass caps at all. Were those carbon comp resistor's leads not long enough to reach the turrets?  Makes no sense to do it that way to me, but alas it's already done.


Please post voltages for all the tubes so we can have an idea of what is going on in the circuit.  And we request you post a schematic so here it is.


Scroll down to see Deluxe reverb schematic and layout.   Deluxe Models

[mresistor]

how to solder to a turret   Soldering Wire & Terminal Connections - Turret Terminal


Did you use any flux in your soldering?

[mresistor]

OK I see you ran the underboard wires up into the turret and made a hook at the top so the wire won't fall out.  That's good.

[Duncan]

is there any solder in the turret top hole for this connection?

I’m pretty sure that one has the lead wrapped around the turret and soldered in place

[mresistor]

These connections are suspect

[mresistor]

I realize that people know F&T capacitors are really good and not too too expensive. But the size of the 25uf 25v ones you picked out make it difficult to physically install and make a good looking amp circuit.  It would be better to use Sprague or Mod electronics cathode bypass caps.  the mods are really small and have double the voltage rating. Many of us have used them and like them.  Capacitor - Mod® Electronics, Aluminum Electrolytic, 105°C, Axial Lead | Antique Electronic Supply


take a look at this board for comparison   

[mresistor]

Ok bro  I've just been addressing physical stuff,,   post up all the voltages of the tube pins so we can verify what is going on in the amp please.

[Duncan]

Ok bro  I've just been addressing physical stuff,,   post up all the voltages of the tube pins so we can verify what is going on in the amp please.

I reflowed the solder to all the above spots flagged and to any others that weren't 100%.

Here are the voltages:

V1:
1 - 213v
2 - 0v
3 - 1.6v
6 - 205v
7 - 0v
8 - 1.6v

V2:
1 - 211v
2 - 0v
3 - 1.6v
6 - 217v
7 - 0v
8 - 1.6v

V3:
1 - 464v
2 - 0v
3 - 9v
6 - 464v
7 - 0v
8 - 9v

V4:
1 - 218v
2 - 0v
3 - 1.7v
6 - 211v
7 - 0v
8 - 0v

V5:
1 - 454v
2 - -42v
3 - 0v
6 - 408v
7 - -42v
8 - 0v

V6:
1 - 264v
2 - 40v
3 - 70v
6 - 260v
7 - 42v
8 - 70v

V7 (6V6):
1 - -28v
3 - 471v
4 - 0v
5 - -28v
6 - 0v

V8 (6V6):
1 - -28v
3 - 471v
4 - 0v
5 - -28v
6 - 0v

V9 (5AR4):
2 - 471v
8 - 471v

[mresistor]

Looking at V6 PI pins 2 & 7 grids that looks like a lot of volts there. I'd say check the .047uf couplng cap from V1B plate.

[ghostinthescope]

Hi Duncan.

No voltage on power tube pins 4 and 6 means the screens aren’t hooked up to the b+ voltage. You might check to see if you missed a connection there. In your photo it looks like one of the 470 ohm screen grid resistors isn’t soldered to the lug and I can’t see any connection that goes to the b+ voltage. (See node B on the schematic).

Also worth noting that v4 pin 8 should read a volt and a half or so like the other cathodes on the preamp tubes. You marked it as 0v.

Good luck! It’ll be great when you get it singing.

[shooter]

EDIT:
close enough
https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_reverb_ab763_schem.pdf

 

[mresistor]

Shooter I posted the RR link in post #2     also  it's just a Fender AB763 DR 
https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_reverb_ab763.pdf

[shooter]

reply #2 has too many hoops to jump through, I got cut from Basketball, became a wrestler 

[mresistor]

reply #2 has too many hoops to jump through, I got cut from Basketball, became a wrestler 

...and you can't wrestle with scrolling down a ways..     

[mresistor]

Duncan also check the .1uf coupling capacitor going to V6 pin 2.

[Duncan]

Hi Duncan.

No voltage on power tube pins 4 and 6 means the screens aren’t hooked up to the b+ voltage. You might check to see if you missed a connection there. In your photo it looks like one of the 470 ohm screen grid resistors isn’t soldered to the lug and I can’t see any connection that goes to the b+ voltage. (See node B on the schematic).

Also worth noting that v4 pin 8 should read a volt and a half or so like the other cathodes on the preamp tubes. You marked it as 0v.

Good luck! It’ll be great when you get it singing.

Welp, turns out I was missing B+ to the power tubes, like an idiot. The amp is now making guitar sounds, as it absolutely should.

The only remaining issue(s) are that V4 is very microphonic (I've tried a few different tubes in that spot, and it's still pretty gnarly), and there's a pretty noticeable hiss.

I'm sure it's a lead dress issue. I'll likely redo the leads for V4 (the hiss goes away once I pull that tube).

I also upped the dropping resistors in the dog house to 22K to tame some of the voltage to V3 and 4.

[mresistor]

Glad to hear you got it sorted out.   

[Duncan]

Thank you, everyone!