Shunt regulator voltage test anomaly

[maarten]

Hi,

I have shunt regulator A side voltage (top of metal tab MJE5731A) at 220V, very stable
I have shunt regulator B side voltage (top of metal tab MJE5731A) at 261V, also stable
All LEDs light up fine

I may have damaged the MJE5731A a little due to a mistake before when I had to pull it out. However, I checked resistance between all legs (no short circuiting of the legs), and between the legs and the metal tab (only the middle leg is connected to the metal tab) and all seems in order.

I left all tubes in when doing this test.
Any idea what could be the cause here?

 

[maarten]

Some voltages:

kregA 2V              kregB 4V
1A 265V              1B 264V
+regA 220V.        +regB 260V
bregA 220V.        bregB 260V
OA 220V              OB 260V
xA 1V                  xB 2V
bA 0V                  bB 0V 

 

[Paul Birkeland]

The joints on the terminal strips under that C4S regulator board don't look to be soldered.

 

[maarten]

This isn't the C4S regulator board.
Note that I received some blue 100 Ohm 3W resistors which replace the white ones in the manual, which may lead to the confusion.
Is your trained eye seeing something unsoldered here?

 

[maarten]

I found it Paul, I'm elated! D3 and D4 were soldered together due to a small blob of solder. Wow!

I now have perfect 220V on both transistors.

 

[Paul Birkeland]

I was looking at the terminal strips under that C4S board, which look to have unsoldered joints.  You also have a resistor lead at pin 7 on the regulator socket that is trying really hard to short pin 7 to pin 8.  CHP-170 side cutters will be really helpful for better trimming.