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Showing posts from January 10, 2018

Tectronix 465 last update

To finish the long story about repairing The 465 is working fine now
I found a solution to prevent damage by possible CRT HV flash over
I just inserted a protective 860k resistor ( could be 1M ) in series with the -2450V  cicuit
Cut the trace direct after the HV diode   see  below the point "test onderbroken"
860k  gave a drop of only 100V    no problem for the HV regulator
the resistor can be low Wattage only 0.0116 W 100V 860k
The cathode current is 116uA neglecting the low parallel load of multiple M OHm
Since then only 1 time there was a breakdown of all voltages "light outage" but just switching off and on and all was working again  no collateral damage...
I use the Tektronix 465 again and live with the occasional break downs until i find a KRT replacement. But  after some warm up time with break downs and return it works stable for hours.
BTW a 100MHz b.t.w.
Hantek DSO5102P USB Digital Storage Oscilloscope 2Channels 100MHz 1GSa/s   can be purchased for 208€  …