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

OldTechFan96 · 7th Jun 2019, 5:16 pm

I've checked all of the smoothing capacitors in the PSU (both HV and LV) and they are not leaky (Hunts tester) and show low ESR.

I tried the brightness setting procedure and the level of brightness did increase slightly. Unfortunately the trace is still barely visible in normal lighting. Lots of ripple I think!

wme_bill suggested in post 46 that low CRT emission manifests itself as low contrast and blurriness. Despite being dim, the trace can be adjusted to be quite sharp! A glimmer of hope for the CRT?

The ripple in the trace is another problem to diagnose. The main problem at the moment is the lack brightness from the CRT. I'll start checking the CRT circuit. Especially around the blanking circuit. What does this do?

7th Jun 2019, 5:16 pm	#79
OldTechFan96 Octode Join Date: Jul 2017 Location: Newcastle Upon Tyne, Tyne & Wear, UK. Posts: 1,186	Re: Hameg HM307-3 Cleaning and Repair I've checked all of the smoothing capacitors in the PSU (both HV and LV) and they are not leaky (Hunts tester) and show low ESR. I tried the brightness setting procedure and the level of brightness did increase slightly. Unfortunately the trace is still barely visible in normal lighting. Lots of ripple I think! wme_bill suggested in post 46 that low CRT emission manifests itself as low contrast and blurriness. Despite being dim, the trace can be adjusted to be quite sharp! A glimmer of hope for the CRT? The ripple in the trace is another problem to diagnose. The main problem at the moment is the lack brightness from the CRT. I'll start checking the CRT circuit. Especially around the blanking circuit. What does this do?