Re: Tektronix 532 LV rail shorted


Rajesh VS
 

Have you checked all the electrolytic caps to confirm none are leaking ?
also I guess you meant R110, which is the limiting resistor to the
plug-in. If that is burned, either the plug-in is shorted for -150V or C110
is bad.
After powering off , you can measure resistance to ground from each section
of the power supply output to confirm none are short. Each rail should be
~1k-5k Ohms.

-150V is the reference rail for all LV outputs, so if -150 is dead/bad,
none of the other will come up properly

If you want to isolate the transformer, as John said, you can remove all
5V4G tubes (note their positions to later put them back where they came
from ) and try.
You can measure AC output from the transformer to check for correct
voltages. Remember all heater and +100V rail is still active.
If you want to disconnect +100V section , remove connection to Terminal 14
of the transformer.

I would suggest then start with just -150V and see if its coming up
properly, and then move up one rail at a time, to +100(reconnect
Terminal#14) , +225, +350 by reinstalling the 5V4G tubes.

Also, check the wattage of the "dim" bulb, as these scopes suck a lot of
power.
HTH
rajesh

On Mon, Jan 6, 2020 at 4:11 PM John Williams <books4you@telus.net> wrote:

It has been a while since I had to fix a 503-series power supply. But when
C640 blows it shorts and blows the 10 ohm fuse resistor. If there are solid
state rectifiers one or more of them could also be blown. If there is a
tube rectifier you can pull the tube and see if it will power up. There is
also an electrolytic on the top by the hv supply which filters the -150. It
could also be somewhere else that is shorting the -150. There is a lot of
interconnection.



--
/Rajesh

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