Deluxe Reverb RI Bias questions as not same as my BF Super Reverb and Problems

[MWJB]

B+ voltage & idle current, in fact any current draw on any of the PT secondaries are linked. More current draw = less voltage & vice versa...on some amps you might see 40vdc+ variance, with the same tubes, at extremes of bias. However you set the current to where it sounds best, without burning anything up. Then you live with the B+ that you get...unless you have scope in other regions to adjust B+ like subbing rectifiers or using zener diodes.

[vavlehead]

IMHO..

to set bias on fixed bias push/pull amp the most accurate way.

of course if you dont know how to be safe here... do not do any of this!!!

you need 2 DMM.
set one to ma and the other to ohms
measure connect the leads of the 2... what you are doing here is measuring the ohms of the DMM ma circuit. it should be like 2 -10 ohms.

Now measure the OT ohms, Center tap( red ) to pin 3 (blue/brown wires) on the tube sockets.
it should be some where around 30 - 200 ohms. or higher in some cases.

you can now know what percentage of the current will flow through the meter and the OT respectively.
If the DMM ohms is like 2 and the OT sides are like 140 each than you dont even need to do the math... but if you have say a twin reverb where the OT is like 35 ohms a side and your meter is 10 ohms you should be very aware of it and do the math.

Resistors in Parallel - Wikiversity



now you can measure the MAs that the tube is pulling. With amp warmed up and on STANDBY!!! the DMM that you know the ohms of the MA setting... hook the red lead to the center tap of OT. hook the black lead to one of the pin 3s.

Put stanby to ON. you meter should now give you the MA going through it. if you have done the math you know what percentage of the total draw that is and you can set it accordingly.

Check the other pin 3. and of course double the numbers if you have 4 power tubes.

[vavlehead]

B+ voltage & idle current, in fact any current draw on any of the PT secondaries are linked. More current draw = less voltage & vice versa...on some amps you might see 40vdc+ variance, with the same tubes, at extremes of bias. However you set the current to where it sounds best, without burning anything up. Then you live with the B+ that you get...unless you have scope in other regions to adjust B+ like subbing rectifiers or using zener diodes.

Hey MWJB...

The Tube CAD Journal, Heater Concerns

Its called a transformer "regulator factor".. in theory the voltage should not drop and should be constant. its not a factor of OHMs law that is.
its a pretty cool article... It seemed to have learned me..

[MWJB]

Tell me which popular guitar amp uses a regulated supply?

[vavlehead]

Tell me which popular guitar amp uses a regulated supply?

Doh!!!.. Sorry... I mean "Regulation Figure"...

"Depending on how good the transformer's regulation figure is, a lower or higher resistance load will see a lower or higher voltage."

[Newguy]

Yellow wire from pin 8 just goes to ground on the PCB. You can still add the 1ohm resistors, you can use a solder tag under one of the tube socket retaining nuts for your ground connection. Remove the yelllow wires completely.

Or, assuming that pins 1 & 8 are tied together with the yellow wires, or that pin 1 is unused (check this - they should be as the grid stoppers - R60/R61 - that run from pin 1 to pin 5 on the 60's BF are mounted on the PCB board in the RI), you can mount one leg of the 1ohm through both pin 1 & pin 8, leaving the resistor body & a small loop sticking out (away from other components, chassis & wires etc.) then reattach the yellow wires to the free end of the 1ohms. Place your meter probe on the bridge between pin 1 & pin 8 to take readings, rather than stressing the actual resistor.

Or, buy some bias probes, then you can rebias without dropping the chassis.

MWJB (or any one who knows), after thinking about this, can I just solder 1 ohm resister from pin 8 to chassis ground on each 6v6 tube socket?