With the 32v supply at 30v, the +/-5v readings make perfect sense as the reference
for those two regulators is the 32v supply. [30/32x 5] = 4.68v Check the DC and AC
voltages across C721. You should see around 50vdc there.
With equipment this old it is not uncommon to find multiple
failures of aluminum electrolytic capacitors which often dry out with age.
This is not true for tantalum types, however, they do not have the same age related
failure mechanism.
There won't be any +95 volts until you have 50v at C558.
Dave
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On Sat, Aug 29, 2020 at 07:07 AM, Harrison wrote:
I checked F558 and to my surprise it was blown. I know I had checked it
numerous times and it was okay. It must have blown during one of my probing
expeditions. I noted with or without F558 the unit powers up and CRT
illumination and power on light work. I lifted the outer lead of C558 and it
read 8.34 micro Farad (an in spec reading).
I was thinking of staying out of the scope for a bit and spending more time in
the manual rereading the circuit theory and operation theory. I say that
because I am confused and going in circles. After replacing C741 I had a
solid 32V, +5V and -5V at the TPs. The 95 TP read +7.58. As time has passed
those readings are now 30V, +4.7V and -4.9V. The 95V TP reads +7.5V. The
junction between CR582 and C582 reads +7.4V. These readings were all taken
with the same meter. Nothing else was done nor any other components replaced
between the two sets of readings. Monitoring the readings now for a bit it
almost seems like they discharge a bit. I.E. like a capacitor discharging.
I also noticed that immediately after replacing C741 the power on light would
illuminate steady when the power switch was pulled. Now when I pull the power
switch on it seems to blink/flicker once or twice before remaining on steady.
Granted there is a linkage and several mechanical connections that might just
be suffering the ravages of time and this might be expected.
Regardless, I am just Easter egging now and need to get smarter on the
circuits and relationship between them. Don't know where else to go from
here. Plus like I said in my first post I am a mechanical guy with limited
electrical/electronic theory schooling or background. While I read a lot, not
everything sticks.
Anyway, any and all ideas past and future are appreciated. The group has
gotten me this far. I don't know if I am close to the goal line or still off
in left field. Stay safe and healthy. Harrison N1FAM
