I looked at the wiring diagram for a b5100 series and then a b7100 series.
Alternator test bench wiring diagram.
Typical alternator wiring by james stevens.
Alternators produce electricity to power electrical devices and to charge batteries.
Wiring diagram arrives with several easy to stick to wiring diagram directions.
Model 897 manual.
Model 881 manual pages 1 59.
The b5100 series has two output wires on the dynamo and a total of 4 wires on the rectifier one of which is a ground.
You find a strong magnetic force immediately pulls the screwdriver towards it even if the screwdriver is a reasonable distance away if there is alternator field current.
Model 881 test lead chart.
Model 897 test lead chart.
Model 881 manual pages 60 107.
Voltage and amperes varies depending on the type and its purpose but car alternators are usually 13 to 15 volts and produce between 50 and 100.
How to bench test your alternator don t forget to subscribe.
Repeat the test using the screwdriver.
My sense is you have married incompatible parts.
Place the metal end of the screwdriver near to the nut on the alternator pulley.
Amfor electronics alternator and starter test bench downloads.
Model 897 brochure.
The b7100 is a completly different story with a rectifier with more than 3 wires and a ground.