5y3 ??

[Carlin Mitchell]

Does somebody have a minute to walk me through this ? I got a 272BX hammond PT from RJ. It's my first amp... champ5F1. I'm getting ready to put the board in and am soldering up all the hook up wires. The 5Y3 rectified voltage leaving the tube is confusing me. PM me if you have a moment. What pin and what color wire is the High voltage rectified voltage coming from ? Maybe my understanding of the OLD schematic is off.

[UR12]

Does somebody have a minute to walk me through this ? I got a 272BX hammond PT from RJ. It's my first amp... champ5F1. I'm getting ready to put the board in and am soldering up all the hook up wires. The 5Y3 rectified voltage leaving the tube is confusing me. PM me if you have a moment. What pin and what color wire is the High voltage rectified voltage coming from ? Maybe my understanding of the OLD schematic is off.

Carlin

The 5y3 uses a directly heated cathode which means that the heater IS the cathode. Your high voltage would come off of pin 2 or 8. You just need to make sure your 5v heater winding (usually yellow wires) on the transformer isn't grounded and you should be good to go.

[Carlin Mitchell]

across the two yellows off the PT I get 6 volts but either to ground I'm getting line voltage .. is that right ?

[tribi9]

Carlin

The 5y3 uses a directly heated cathode which means that the heater IS the cathode. Your high voltage would come off of pin 2 or 8. You just need to make sure your 5v heater winding (usually yellow wires) on the transformer isn't grounded and you should be good to go.

What is the polarity of the high voltage wires on a transformer? Negative, Positive and ground? See im kinda confused because I understand the plate requires a positive charge from the transformer. So then would you wire the positive lead of the transformer to pin 4 then short that to pin 6, and then wire negative lead to the cathode? But since the cathode is the filament in this example, wouldn't it require a 5 V from the transformers secondary as opposed to the high voltage negative lead? Does that make sense?

[UR12]

across the two yellows off the PT I get 6 volts but either to ground I'm getting line voltage .. is that right ?

Across the yellow wires off of the PT when you have the5Y3 hooked up you should see 5VAC If you measure from ground to say pin 2 you should see high voltage DC. Not sure what you are refering to when you say "line voltage"

Tribi9

The plates of the rectifier tube have AC voltage on them from the high voltage winding on the power tranny. Coming out the other side of the tube (the cathode) you will see high voltage DC to ground. The rectifier tube is the only tube in the amp that you will apply AC voltage to the plates. The AC voltage is changing from positive to negative 60 times a second. The moment in time that the plates see the positive side of the AC it will allow current to flow from the cathode to the plate. While the AC is going negative, no current will flow. The center tap of the High Voltage winding is grounded and each plate in the rectifier tube will see two different phased AC voltages so when one plate is positive the other is negative. Then they switch and the other is positive and the one that was positive will become negative. You are rectifying both haves of the AC sine wave and this is called Full wave rectification.

[tribi9]

Tribi9

The plates of the rectifier tube have AC voltage on them from the high voltage winding on the power tranny. Coming out the other side of the tube (the cathode) you will see high voltage DC to ground. The rectifier tube is the only tube in the amp that you will apply AC voltage to the plates. The AC voltage is changing from positive to negative 60 times a second. The moment in time that the plates see the positive side of the AC it will allow current to flow from the cathode to the plate. While the AC is going negative, no current will flow. The center tap of the High Voltage winding is grounded and each plate in the rectifier tube will see two different phased AC voltages so when one plate is positive the other is negative. Then they switch and the other is positive and the one that was positive will become negative. You are rectifying both haves of the AC sine wave and this is called Full wave rectification.

Awesome, thx again for taking the time to explain basic concepts that I should be Googling instead. (Actually, I have! Unfortunately because of all the amount of info I've crammed in such a short time and all the partying that killed a few brain cells in my youth , it does gets a little confusing at times)

So I guess the only way to get full wave rectification is with a dual anode.

On the other post about the 6CA4, you said that the rectified AC goes to a filter cap but here you say it goes to ground? Doesn't this now rectified AC current now provide positive DC voltage to all the plates on the rest of the tubes? If so where would it go first, right after leaving the cap? onto a resistor and then plate of a preamp tube, or onto a resistor and then plate of a power tube? Does it even matter where it goes first?

[UR12]

So I guess the only way to get full wave rectification is with a dual anode. ?

There are other ways to get full wave rectification but this is the most common using a dual diode tube

On the other post about the 6CA4, you said that the rectified AC goes to a filter cap but here you say it goes to ground? Doesn't this now rectified AC current now provide positive DC voltage to all the plates on the rest of the tubes? If so where would it go first, right after leaving the cap? onto a resistor and then plate of a preamp tube, or onto a resistor and then plate of a power tube? Does it even matter where it goes first?

No, the rectified DC does not go to ground. You measure the DC voltage using a Volt meter from ground to the cathode and the CT of the HV secondary winding of the Transformer goes to ground but this is a reference. I my first post I aslo stated that neither of the 5VAC (Yellow) wires can go to ground either as that would also cause a short between B+ and ground.

[tribi9]

So I guess the only way to get full wave rectification is with a dual anode. ?

There are other ways to get full wave rectification but this is the most common using a dual diode tube

On the other post about the 6CA4, you said that the rectified AC goes to a filter cap but here you say it goes to ground? Doesn't this now rectified AC current now provide positive DC voltage to all the plates on the rest of the tubes? If so where would it go first, right after leaving the cap? onto a resistor and then plate of a preamp tube, or onto a resistor and then plate of a power tube? Does it even matter where it goes first?

No, the rectified DC does not go to ground. You measure the DC voltage using a Volt meter from ground to the cathode and the CT of the HV secondary winding of the Transformer goes to ground but this is a reference. I my first post I aslo stated that neither of the 5VAC (Yellow) wires can go to ground either as that would also cause a short between B+ and ground.

Gotcha, thx!

[rfgordon]

Note also that some Hammond PTs have a center tap for the 5V heater supply. DO NOT ground that if you are using a tube rectifier. If you do the high volts (connected to the heater pins of the rectifier tube) will essentially short to ground through the filament winding. That can definitely let the smoke out...

I learned this the hard way!!

[joebob]

Here is some nice info on rectifier tubes.

dave