On Some Strobe units including the Norman 202
There are three basic ways to get the power capacitors in a strobe up to the correct voltage, 1. By a high voltage transformer, 2. By a voltage tripler circuit using a ladder of diodes and capacitors. 3. High Voltage Battery (510vdc battery) The Norman 202 has one power capacitor charged with a transformer's output rectified with diodes to a DC Voltage. The 202 has two output sockets and a switch that either delivers the same voltage to each or switches in a "resister" in the lower (darker) side. Because part of the power is attenuated by a resistor the total output in the 150/30 mode will be less than the 100/100 selection. In addition to the differences in the selected path with or without resistor, variances in flash tubes (resistance during flash) can cause a difference in output. Balcar used the difference between their short and long "U" shaped flashtubes to create a ratio of 1::2 in outputs. If you use a tube rated for 400w/s vs. 200w/s the resistance may be different and the output therefore different. At the time the Norman 202 was first introduced trigger voltages were the 70 to 200vdc range for many of the units. The Norman LH4 head had circuitry in the head stepping down the voltage and indicating a ready voltage via a "neon" lamp. I use either a "slave sensor" or a Quantum Radio trigger when working with digital and older flash units.
IMPORTANT -- Because of the high voltage coupled with high amperage in a power pack, leave the repair to authorized service providers. Norman has a list of service providers on their website.