SE 6BQ5, Power Supply and Preamp overhaul

[MCS Guy]

I was going full steam into this before I slammed into a wall. I realized that I just can't put this all into a box and it works.

I have a Bradford SE 6BQ5 stereo console unit that has the power supply, pre-amp/amp and tuner on one chassis. My original intent for this was to be a simple unit that plays background music on some bookshelf speakers. Basically, I was just going to rip out just the PS and pre/amp circuits and place them in a Hammond chassis. I was even going to reuse all the balance, bass and treble pots/circuits. Seemed like a straight forward project.
But after reading threads, articles and videos, this isn't going to work. Removing the tuner changes the voltage drop and current through the power supply B+. I thought about copying the power supply in the Magnavox 8600 Thread, but my PT is different than his. Also, I can't decide if I want to keep or remove the tone controls and balance pot. If I remove them, do I need 2- 12AX7's or just one?
I downloaded PSUD2 and tried using that to figure out how to overhaul it. It answered some things, but gave me more questions. How does one calculate the load? What Henry Choke do I use? In one episode of Blueglow, Mark was designing/showing a power supply and said to effect that you need a engineering background.

Well, I'm not an Electrical Engineer. I have basic electrical knowledge through automotive repair.

So now I am stuck and confused on where to go on this. I have attached two schematics of the power supply and the preamp/amp. I edited the primary side of the PT to remove the switch and wires for the phonograph. I removed the function selector switch and added 2 RCA jacks for the preamp. I have all new resistors and capacitors listed in the schematics (I have poly caps for all the disc caps in the preamp). I have the PT and OPT specs from the parts list and what I measured on a DVOM (in DC ohms):

Power transformer: Primary is 117V AC @ .85A (DC Ohms - 5.5)
Section 1 (red) is 540V AC @ CT, .135A DC (DC ohms end to end - 204)
Section 2 (green) is 6.3V AC @2.6A AC
Section 3 (yellow) is 6.3V AC @2.8A AC

Output transformer: Primary is 5500 ohms and Secondary is 6-8 ohms (DC ohms pri - 425, sec. - 2)

 

[s-petersen]

Some of the preamp voltages may rise more than a little, but can be adjusted back down with a resistor change

 

[MCS Guy]

Thanks for your replies. I have planned to buy a Variac sometime in the next few weeks to bring it up slowly to monitor the voltages. I also bought a few CL-70's and I'm adding one after the power switch. I think I will just use the current CR style PS just to get it up and running, then experiment afterwards with a choke. I have already drilled and painted the chassis and finished painting the transformers today. Probably mock install the xformers and tube sockets tomorrow and plan out the tie strips and ground buss.

One question though, whats with capacitor/resistor circuit before the volume (loudness) pot? Is it a low pass filter at low volumes?

 

[MCS Guy]

I'm pretty much finished with the build, I turned out pretty good. I ended up using a choke in series with the 150ohm 10 watt resistor, but its not enough to bring the voltages down. I placed an order to get more resistors to get them right. I'll edit the schematics on the first post when I figure it out.

 

[primosounds]

It really helps when you are customizing a circuit to use PSUD2 as an aid. this will help with voltage when you put in CR or CL modules in the power supply. Sometime you need to put a high wattage bleed resistor of about 12k 10 or 12 watts to help the power supply.