cinderella1, as mentioned already a broken solder joint has no practical effect on a diode's bias. When you have a bad joint, the connection is intermittent (like I told you in chat). When it's intermittent, that means sometimes it acts like the diode is there, sometimes it acts like it's not there at all. When the joint is connected, the diode behaves as it normally would. When it's not connected, it's like the diode isn't even there, so there is no component to have a bias. Do you see now what I was trying to tell you in chat?
Let's say you have a diode in a
series circuit with a resistor and an LED. The diode is forward biased, so current will flow normally. When the diode is joined properly, the LED will light. When the diode joint is broken, the circuit is broken, so the LED does not light. If there is just a crack in the joint but it is still electrically connected, the LED will still light.
An intermittent joint means it can connect and disconnect many times a second, or maybe once every few years. If it is disconnected, the LED will not light. If it is connected, the LED will light. It's as simple as that.
Don't over-think it.