Eros 2 Final Voltage Check Issue

[mstacker]

I finished my final voltage check for my Eros 2 Phono preamp, and I have a couple number off:

1A : 210-230V = 217v
1B : 210-230V = 217v
OA : 155-185V = 211v ***
OB : 155-185V = 156v
OC : 95-105V = 59v ***
OD : 95-105V = 99v
OKA : 95-105V = 63v ***
OKB 95-105V = 99v
OKC : 0.7-2.0V = 2.0v
OKD : 0.7-2.0V = 1.6v

I also check the voltage on the 2 EF86 tubes. I think one of the connections in the 9 pin socket is off.
Tube A (these are numbered 1 through 9 based on the instruction. When looking at the underside, 1 is left of the gap, and 9 is clockwise around on the other side of the gap)
1) 63v
2) 0v
3) 0v
4) 58v
5) 52v
6) 58v
7) 0v
0v
9) 0.2v

Tube B
1) 97v
2) 0v
3) 1.8v
4) 59v
5) 53v
6) 96v
7) 0v
1.8v
9) 0v

I also rechecked MJE5731A are both 215v with is right in the range 210-230V.

Any guidance would be greatly appreciated.

-mat

[Paul Birkeland]

Typically I find in situations like this that there are soldering issues on the front C4S board.  I would take it off and reflow all of the joints on the PC board aside from the ones with LEDs, as they are somewhat temperature sensitive. 


I have fixed at least a half a dozen Eros 2 kits with roughly this exact problem, and all of them had soldering problems on that front board causing the issue.

[mstacker]

Thankyou. I will look into that.
Do you have an idea what would cause the different voltages between the tube A and B (EF86s)?
Are these input voltages that are going to the tube, or output voltages being created by the tube?

[Paul Birkeland]

Do you have an idea what would cause the different voltages between the tube A and B (EF86s)?

Solder joints.