Re: Tektronix 532 LV rail shorted


randolphbeebe@...
 

Rajesh,

I have not had time to look at it again yet. Hopefully this weekend. One spot of good news is that I just checked the fuse and it was blown. That would sure account for no voltage at C640!

One thing that is curious however, upon reviewing the schematics of the LV power supply I read my notes and recalled that when I measured the voltage at pin 16 on the transformer it measured +89V AC. I do not expect to see the voltage near the correct numerical value on the crippled circuit but POSITIVE voltage? Would that account for the symptoms as well since both C640 and C110 are installed positive to ground?

Can that positive voltage be coming from one of the other supply rails perhaps, the +350, +225 or the +100? Or a fault in the transformer. It gives me something to think about when I read about the circuit description.

Your time distribution method is excellent, I am trying to get away from the neophyte's instinct to just shotgun parts to "see if it works now".

Randy

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