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

OldTechFan96 · 21st May 2019, 7:30 pm

Thanks for that WaveyDipole, here is how I got on:

With the four pin connector to the Y-preamp board removed 0V was measured on the base of both TR123 and TR124.

I applied 15V to the base of TR123 and TR124. I've only got a single output bench PSU so I improvised to apply voltage to both transistors.

Collector of TR124- 89V
Collector of TR123- 93V

Emitter of TR124- 14.9V
Emitter of TR123- 15.5V

The voltages are not quite balanced but are close. Nothing appears on the CRT.

21st May 2019, 7:30 pm	#14
OldTechFan96 Octode Join Date: Jul 2017 Location: Newcastle Upon Tyne, Tyne & Wear, UK. Posts: 1,178	Re: Hameg HM307-3 Cleaning and Repair Thanks for that WaveyDipole, here is how I got on: With the four pin connector to the Y-preamp board removed 0V was measured on the base of both TR123 and TR124. I applied 15V to the base of TR123 and TR124. I've only got a single output bench PSU so I improvised to apply voltage to both transistors. Collector of TR124- 89V Collector of TR123- 93V Emitter of TR124- 14.9V Emitter of TR123- 15.5V The voltages are not quite balanced but are close. Nothing appears on the CRT.