[Nisgeis]

Hello chaps. There are three main indicator lights on a Mark 3 TDC. The first one is on the PK section and tells you if the PK is on or not. The other two are on the angle solver unit. There is a lamp each for forward and aft torpedo solutions. If the solution that the angle solver has come up with has been solved and the solution would have a torpedo run of more than 300 yards or more than the maximum torpedo run length of the type of torpedo being used. Also, if the gyro angle is greater than that type can be set to the lamp will not be lit either.

Furthermore if the TDC has to do any kind of rapidly changing solution, there is a possibility that the internal mechanism will not be running fast enough to be providing the right problem from the PK and hence the problem i snot being represented properly, so the Generating lamp will go out. Once ot has cought up and passed the right problem on to the angle solver, the correct solution lamp will go out of the angle solver has not yet caught up with the right solution. If the captain manouvers hard (thus making target bearing change very quickly) or the range is very close, then the target problem may be changing faster than the TDC can keep up with, so this will also make the correct solution lights go out until the TDC follow up heads are matched and the TDC has caught up with the solution. The term they use in the manual is 'in synchronous operation'. E.G. No mechanical lag!

As far as I know, the correct solution lamps were marked with an 'A' and the power light was blank, but I'm not sure about that.

EDIT: The manual says that there are two bulbs for each inficator light, so a single blown bulb wouldn't affect the lights.