Fender Bassman Head 6G6-B circuit conversion

[tonefiend]

Question: My bias supply capacitor is 25uf 50volt, does it make sense to make the voltage higher like 25uf/100volt?

thanks for your help

[The Dude]

If you're going to replace it, yes. You might as well put in the cap rated at higher voltage.

[tonefiend]

I have a 100uf/100volt - Would that be too high a rating, as the shcematic calls for a 25uf? Could that damage stuff?

[The Dude]

It won't damage anything. If you have it, go ahead and use it.

[Enzo]

And remember the bias supply is negative, the positive end of the cap gets grounded.

[tonefiend]

And remember the bias supply is negative, the positive end of the cap gets grounded.

Thanks Enzo good to know! fortuantely I always take pictures prior to yanking/replaceing old components for reference. So I will put it back in the way
it came out. However I did not realize that positive side is tied to negative, until you mentioned it, now of course I can see it on the schematic. I'm always
learning something. thanks again

[tonefiend]

I have a 100uf/100volt - Would that be too high a rating, as the shcematic calls for a 25uf? Could that damage stuff?

Just for clarity, 100uf is 3x the capacity of a 25uf which means that it will take 3 times longer to charge? I just wanted to double check that this is ok to use a higher capacity cap here. thanks for your input

[Helmholtz]

Just for clarity, 100uf is 3x the capacity of a 25uf which means that it will take 3 times longer to charge

Actually 4 times.
But will charge in less than a second.

[tonefiend]

Quick quesiton: If when pulling 2 Power tubes, which I intend on doing. Does it somehow change the ohm rating of the speaker output? BTW: the schematic doesnt show
what the ohm rating should be for the speaker output. This is the Fender 6G6-B circuit with a piggy back speaker cabinet that has 2 speakers. thanks very much

[Helmholtz]

Quick quesiton: If when pulling 2 Power tubes, which I intend on doing. Does it somehow change the ohm rating of the speaker output? BTW: the schematic doesnt show
what the ohm rating should be for the speaker output. This is the Fender 6G6-B circuit with a piggy back speaker cabinet that has 2 speakers. thanks very much

See post #11 (quick answer ).

[tonefiend]

Hello Making Progress on the Amp. So Far I have rebuilt the Normal channel, and most recently I rebuilt the Output section putting
it back to stock. This Amp originally had 4 output Tubes, so I decided to put it back to stock 2 Output Tubes, which ultimately
was a good move, because it is much quieter now, whisper quiet. I posted pictures of the old to new filter caps, I used F&T filter caps, if you look at the pictures you can
see the old filter caps, which had exploded, and spewed its guts.

Another Task was to Remove the Old Speakers from the Cabinet and Install a new Speaker. To lighten up the cabinet I removed the 2
JBL speakers (D120f, and D130f) which have both fallen apart, and put in an Eminence Canabis Rex 8ohm 50 watt speaker which I had as a spare.
This job was not for the faint of heart. All of the screws on the back of the cabinet that needed to be removed were rusted out, there are
I think 20+ screws that I had to remove with a screw reamer. When I finally got the back off, all of the nuts holding the speakers in were
either glued on, or some type of laquer was on their that made it impossible to get the nuts off. So I had to remove the baffle, and then put
a solvent on all of the nuts to get them off, this literally took probably 10 hours of work to get the new speaker in. The reason why everything
was rusted out, the back story of this amp if you will, is that it sat in a basement for 40 years, and would frequently flood. Now the amazing
thing and a testament to Fenders cabinet build quality, is that the water never got passed the baffle, when I removed the back is was bone dry
inside the cabinet! and still in great shape. Even the baffle is still usable. I must say the cabinet sounds fantastic with the 1 canabis rex speaker, and is extremely light
to carry around.

I have posted several pictures of my progress.

Question:
Im wondering if someone could tell me on the Output Tubes, what the purpose of the 1.6k resistor is between pins 1 & 5? According to the schematic pin 1
should be tied to pin 8(which is attached to Ground) All of the output tubes had this resistor. I posted a picture pointing this out.

Also, does anyone have any ideas on how to plug up the empty holes where the old tube sockets that were removed?

I will be posting more pictures as I progress.

thanks for your help and responses

[Bloomfield]

The resistors are the grid stoppers. Pin 1 is unused on the 6L6 and so the socket lug is commonly used as a tie point to mount those resistors. If you look around the electrical section of building supply stores, you might find knockout plugs for electrical boxes that would be the right size to snap into those unused holes in the chassis.

[Helmholtz]

The resistors are the grid stoppers. Pin 1 is unused on the 6L6 and so the socket lug is commonly used as a tie point to mount those resistors.

But then pins 1 and 8 must not be connected as shown in the original layout. (And it wouldn't work with EL34s).

[tonefiend]

Thanks, Pin 1 and Pin 8 are not connected, its only pin1 and pin5 with a 1.5k resistor tied together

[tonefiend]

Hello,

When I turn on my amp, with the Standby on, and then I turn off the Stand-by switch I get a really loud "POP" So far when I power the amp up with the Stnadby switch in the off position. It does not seem to POP,

Any Ideas on what this might be? Possibly a bad SB switch?

I was powering the amp up with the standby switch on because I put a slightly larger bias cap in. It calls for a 50uf and I put in a 100uf.

Can I cause any damage by powering on the amp with the SB switch off with a larger cap?

thanks in advance for your help