Re: 7603 working .... then blank



Update on my 7603 scope ......

Removed Plug-ins and turned on Scope ...... Scope still dead.

Checked voltages at Pin P1171 .....
-15vdc and -50vdc ..... okay.
+5vdc, +15vdc, +50vdc and +130vdc ... all way out of spec.

Voltages at Pin P890 (unregulated V) show that all supplies are larger than expected .... probably due to being unloaded .....

Except the +130vdc supply .... which is +97vdc and -7.8vdc (instead of +130vdc and +40vdc).

I note that the Regulation circuits rely on other supplies to power the transistors. I am assuming for the moment (away from Home) that the +50v powering the +130v Regulation section (Q850, Q852 etc) is unregulated rather than regulated +50v .... ?? And just maybe, there might be no other faults .... 🤩

Next step is to check this Supply.


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