Shunt regulator help [resolved]

[jjvornov]

I'm in the midst of my Eros build and have a problem at the Shunt regulator checkout stage.

First, only the LEDs on the A side of the board light.

On the wire connected to D6 I get 310 volts, on the D1 side I get 223.

I checked a few more voltages
KReg A is 4.4 V
KReg B is 22 V

IA is 313, 0A is 220
IB is 311, 0B is 313

At this point I've double checked the board connections and reflowed a few solder joints with no change. But with the connections it's hard to get to them all.

James

[Paul Birkeland]

The 22V at Kreg B is something I have seen when an MPS4250A is installed where a TL431 should be.

-PB

[jjvornov]

Paul-
 Definitely have the TL431's both on the board. Is it possible there's a bad solder connection on it? Can I reflow connections like that without disconnecting the board?

James

[Paul Birkeland]

Your voltages could also indicate that there's basically no current flowing through the 12BH7.  This could be from a flaky solder joint either on the board, or on the socket itself (are both halves of the 12BH7 glowing?).

[jjvornov]

Paul-

All good now. I took the board off and resoldered the tube pins and a few board connections. I think I found one jumper that was in and not soldered! So I reinstalled- got pretty good with the desoldering braid and got all 4 leds lighting and the right voltages on both sides.

Building a kit like this is fun, frustrating at times, but when you get it working, sublime

James