UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Hameg HM307-3 Cleaning and Repair

OldTechFan96 · 12th Jun 2019, 3:25 pm

I've done some more measurements:

Pin 5 of opto coupler: -870V

E of T352: -870V

C T352: -868V

B T352: -869V

T353 has been changed.

The voltage at R366 is -867V and is correct for the blanked state. It stays the same no matter how the controls are manipulated.

The HV pot has not been touched since the -1000V rail was fixed.

-867V rail measures -870V.

-900V rail measures -903V

I've lifted the input side of R363, grounded it and took measurements at pin 4 of the OC IC and the voltage measured is -872V. This does not change nomatter where the hor. ext. button is pressed in or not.

12th Jun 2019, 3:25 pm	#98
OldTechFan96 Octode Join Date: Jul 2017 Location: Newcastle Upon Tyne, Tyne & Wear, UK. Posts: 1,178	Re: Hameg HM307-3 Cleaning and Repair I've done some more measurements: Pin 5 of opto coupler: -870V E of T352: -870V C T352: -868V B T352: -869V T353 has been changed. The voltage at R366 is -867V and is correct for the blanked state. It stays the same no matter how the controls are manipulated. The HV pot has not been touched since the -1000V rail was fixed. -867V rail measures -870V. -900V rail measures -903V I've lifted the input side of R363, grounded it and took measurements at pin 4 of the OC IC and the voltage measured is -872V. This does not change nomatter where the hor. ext. button is pressed in or not.