When should I have soldered the 2 drain wires at the Center terminal of D?

[PaulG]

I just got to page 54 of the EROS instructions where the Shunt Regulator board is installed. 
I have 2 drain wires attached on page 48, but not soldered to the center of D.
If I continue with the installation of the Shunt regulator board, soldering the two drain wires that I attached on page 48 will get a lot more difficult.
I'm working from a set of instructions printed out in 2015.
Is there a reason to leave the drain wires unsoldered?

Thanks for putting up with my OCD!

[Paul Birkeland]

I would go ahead and solder them.  I don't remember there being anything else that connects to that point.

If you are building a kit with parts that are 5 years old, do be sure to use your meter to test all the LEDs after they are soldered.  They slowly absorb moisture over time and can be damaged from soldering if they are allowed to sit in a humid environment for a few years.

[PaulG]

Thanks for the answer.  I will go ahead and solder the drains to center D.

The kit was in a bedroom drawer in San Diego so I hope the LEDs are ok.  I guess if any of them fail to light up that is a possible failure point....

[PaulG]

To test the LEDS with a meter am I just looking for continuity? or just for all of then to have the same resistance?

[Paul Birkeland]

Most meters have a diode setting, and one orientation of your probes should be able to light up each LED or at least say "1.57V" on the meter display.

[PaulG]

I got all 4 of the diodes to light up when I put in the tube and powered up the unit to test shunt regulator voltage.
The red wire from D1 tested a very solid 223.1 with all 4 diodes lit.
The red wire from D6 tested a wavering 110 VDC  The 2 diodes on the B side of the Shunt regulator board lit right away with the ones on the A side lagging about 15 or 25 seconds behind.

I repeated both tests because I hadn't checked the Tube heaters.
D1 was exactly as before 223 VDC and I could see the Tube heaters lit.
D6 tested differently with an immediate surge to 330 VDC and then settled to a solid 139 VDC.  The tube heaters were lit.

I'm going to reread every thread having to do with Shunt Regulators but I would appreciate any thoughts.

[Paul Birkeland]

What are the Kreg voltages?

[PaulG]

Thank you for asking but I am afraid I must now reveal exactly how much of a beginner I am. 
I have found the two (A and B) KREG pads. 
Please confirm that the positive probe goes to the +Reg pad on the same end. 
I'm also assuming the board and tube need to be live when I do this.

I have taped off the red leads from D1 and D6 to prevent an accident.

[Paul Birkeland]

Black probe lead to ground, red probe lead to each Kreg pad with the meter set to DC volts.

[PaulG]

Thank you again for your help, support and patience.

KREG A measures 1.86 VDC
KREG B Measures 6.2 VDC

What is the next step in finding my screwup?

[Paul Birkeland]

I suspect you have a soldering issue on the C4S board.  Do both halves of the 12BH7 light up?

1.86V on Kreg and 110V on the plate means ~10mA of current, which is insufficient and not what the board is set for.  You can end up with that for these other reasons:

1.  Swapped 2N2222 and 2N2907
2.  Swapped TL431 with MPS4250
3.  Missing board jumper
4.  Poor solder joints on PC board
5.  Black wires from D3/D8 going to the wrong Kreg terminals on the board

-PB

[PaulG]

All 4 of the heater rods glow.
I will recheck items 1-5 and report back in the morning. 
Thank you again for your knowledge and especially your patience.

[Paul Birkeland]

I have an Eros 1 in for repairs with some similar issues, so it's all quite fresh right now.

-PB

[PaulG]

1. the 2n2907 transistors are on the shunt board version 4.4  in the location from the instructions with the little tab over the outline printed on the board.  They are kind of dull and the 2n2222s on
    the other two boards are still shiny... indicative of something going on inside?
2. The TL431s are in place.
3. All the board jumpers from the instructions appear to be correctly installed.
4.  Looks like time to unmount the PC board and search the other side for the offending solder error
5. Black wires from D3/D8 go to the correct Kreg terminals

I'll let you know if there's any breakthrough.

All the best,

[Paul Birkeland]

Solder joints on the shunt reg PC board can cause problems like this too.