newbe question Flashing the field

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hello I have a couple Questions on flashing the field, I have a lincoln 250 Sa perkins driven Welder that I can not get any out put from . I have replaced the reostat ,full wave bridge, As i was suggested to do from a lincoln Tech, To no Avail, now I need to flash the field. My questions are, On the exciter ,Which brush is the Left and which one is the right/On this welder they say in instructions that the one closet to the iron is Neg. Then they state in their instructions to put on lead from a dc battery to left brush and one to the right brush.Red is neg on these welders for some reason ,black is pos. Which brush do you Lift?Do you have the engine running while holding Dc to the brush Wires?     Thanks in advance
Reply:Originally Posted by Tgrant I have replaced the reostat ,full wave bridge, As I was suggested to do from a lincoln Tech. . .
Reply:Thanks for the reply!  So to flash the field, Do you have the engine running with one brush lifted?Does the pos. side of the battery go to neg. or does it go to the pos.?
Reply:Hello Tgrant,Flash with engine not running.Neg battery to negative brushPos battery to positive brush.Brush lifting is a non-issue, sounds like a step from a manual written for DC commutator.Are you sure you have the correct manual? If you replaced a bridge, this machine must have an AC auxiliary.But really, it's probably not a case of lost residual magnetism, which would require flashing. I'd recomend some systematic checking for voltage with a meter. I'd recommend some systematic checking for voltage with a meter.Good LuckI'm having modem connection trouble today, so that's it for me, for now.
Reply:thanks for your help ,I am getting about 125 dc volts on the brushes at the front exciter.only about 1 to 4 volts at the a/c outletmaybe 5  d/c votes at the weld terminals.
Reply:For now we're at the "things that make you go hmmm" stage.This is some of my hmmm:When was the last time the welder was known to work, and what has changed since then?Back in post #1; When the Lincoln tech suggested changing the rheostat and bridge, was that a long-shot guess, or was there some troubleshooting or other logic behind the parts change?Who changed the parts, and is it known that wires were reconnected correctly, to matching replacement parts?Does your manual match the machine's code number?A schematic is probably the next order of bidness.Good Luck