Re: Tek 7603 Followed Me Home

Chuck Harris
 

What plugins do you have installed?

Without plugins, you might get the green power lamp to
light... assuming it isn't burned out.

-Chuck Harris

Robert Hay wrote:

I have seen this Tek 7603 scope sitting on the table at the Tek Country store for at
least three years. I have tried to power it up and twist some knobs several times
over the years with no response. They have been asking $35 for it and I noticed
today there are about 5-6 price stickers stacked up under the current one.

I have been thinking a 7603 would fit into my ensemble if I clear space for it by
giving another scope to the Tek Museum. So, I asked if they would take $25 for it
and they did. So, here it sits with the covers off and the power supply hanging out
the back. It doesn't do nut-tin when powered up.

The main fuse, the fuse on the regulator board and the one on the power supply board
above the caps are good. I checked the power supply voltages on the regulator board
with the following results:

Volt VDC VAC
130 114 11
50 44 5
5 4.396 0.25
15 13.2 1.4
-15 -13.17 1.3
-50 -44 4.8

Unregulated Voltages

50 66 0.16
-50 -52 13
15 24 0.04
-15 -24 0.1
5 12.4 0.05

Seems to be discrepancies between the ripple on the corresponding regulated and
unregulated supplies which I don't understand.

The 130 volt supply is partly made up from the 50 volt supply and the voltage on the
emitter of Q850 should add about 40 volts but I measure 10.8 volts DC there. Maybe I
see it now, if the 50v supply is at 44 volts there is no way the emitter of Q850 can
get to 40 v.

I appreciate any ideas from folks especially those who have been thru a 7603 before.
Haven't had a chance to research the archive but will do that before doing more
troubleshooting. I can't take another scope to the Tek Museum until I know we can
bring this one back to service.

Bob.






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