"bz" wrote in message
98.139...
The saga continues....

Removing the plug in module DID clear the 100 ohm 'short' to ground on the
100 volt line.

Swapping tubes did NOT fix the -150 volt supply however.
It only measures -131 volts (after several minutes of 'post hv turn on'
warm up). It drifts much more during the warm up than the -150 volt
adjustment pot will swing to voltage. In fact I see very little change as I
adjust the pot.

The 100 volt supply is putting out about 130 volts and the rest of the
supplies look about normal (have not checked the HT supply to the CRT. I
wonder if it being too high could cause all my symptoms).

Measured the current out of the -150 and 100 volt supplies (across the 5
and 10 ohm series resistors). ~.95 volts /5 ohms = 190 ma for the -150
supply
~1.4 volts/10 ohm = 140 ma for the 100 volt supply. I am assuming that
those values are not unusual. I have not looked at ripple, etc., yet.

Looks like I am going to have to measure voltages at several points and try
to make sense of any patterns that emerge.

--
bz 73 de N5BZ k



I don't remember whether you posted that your scope is the older 545 model, or
the later 545A or 545B model.
I still have a copy of the 545B scope handy. As I remember, the low voltage
power supplies are pretty close from the basic 545 thru to the 545B models.
According to my manual, the resistances to ground (power off and all supplies
totally discharged, no plug-in installed) a
-150V 2K
+100V 2K
+225V 2K
+350V 1K
+500V 15K

Ripple specs are pretty tight, and must be to specs for a good trace and
waveform display.
-150V 5mv
+100V 10mv
+225V 5mv
+350V 20mv
+500V 20mv

Going back to your earlier posts, you started with a good -150V source, but all
others were way out of tolerance ????!!!!! Kinda hard to do with this
instrument, since all the other LV sources are referenced to the -150V source.
Are you sure that your test instrument is good?? If you have another source of
known voltage, check it and eliminate or identify that as a source of error.

Next, remove and reseat all the tubes in the power supply section. Old tubes
and sockets get a bit of fungus or mold in the works, and can create all sorts
of havoc. Work the tubes in and out of the sockets several times; you might
even clean the tube pins with a bit of fine emery cloth.

Cheers!!!!!
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.