UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Tektronix 576 curve tracer with periodic screen blanking

Apfelmus · 11th Dec 2014, 10:55 am

I'll think about that. But the HV supply will go in an off-scale mode that maybe is not very representative.

Meanwhile I checked HV voltage directly, it remains constant throughout the cycles. But the voltage on the base of Q855 rises to about 3V. This voltage depends on the position of the Intensity control. When I turn Intensity full CW, I get approx 2.5V, fully CCW its -1.5V. When the fault appears, voltage goes beyond 2.5V.

Your question about the temperature of the mains transformer: after 15 minutes its getting slightly warm, thats all.

cheers
Martin

11th Dec 2014, 10:55 am	#3
Apfelmus Pentode Join Date: Sep 2014 Location: Stuttgart, Germany Posts: 176	Re: Tektronix 576 curve tracer with periodic screen blanking I'll think about that. But the HV supply will go in an off-scale mode that maybe is not very representative. Meanwhile I checked HV voltage directly, it remains constant throughout the cycles. But the voltage on the base of Q855 rises to about 3V. This voltage depends on the position of the Intensity control. When I turn Intensity full CW, I get approx 2.5V, fully CCW its -1.5V. When the fault appears, voltage goes beyond 2.5V. Your question about the temperature of the mains transformer: after 15 minutes its getting slightly warm, thats all. cheers Martin