UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Kolster-Brandes MR10

DonaldStott · 9th Nov 2019, 6:38 pm

Managed to find my Velleman K7000 Signal Injector/Tracer along with the excellent Automatic AF/RF probe constructed for me by Forum member David G4EBT.

As I still have FM but no AM then it seems like the audio stage is working. So I'm working back from there to find where/why the AM signal is not getting through?

Did some basic checks with the Signal Injector and got a loud tone at the middle tags of both the Treble and Volume pots. Also a loud tone on Pin 2 (Control Grid) of V5 (EL84) and on the gram socket when switched to Gram.

I was also advised to check R17 which is 10MΩ to ensure I had connected this new resistor correctly and I have 10.2MΩ between Pin 8 of V4 (EABC80) and the chassis.

9th Nov 2019, 6:38 pm	#134
DonaldStott Octode Join Date: Aug 2015 Location: Glasgow, UK. Posts: 1,850	Re: Kolster-Brandes MR10 Managed to find my Velleman K7000 Signal Injector/Tracer along with the excellent Automatic AF/RF probe constructed for me by Forum member David G4EBT. As I still have FM but no AM then it seems like the audio stage is working. So I'm working back from there to find where/why the AM signal is not getting through? Did some basic checks with the Signal Injector and got a loud tone at the middle tags of both the Treble and Volume pots. Also a loud tone on Pin 2 (Control Grid) of V5 (EL84) and on the gram socket when switched to Gram. I was also advised to check R17 which is 10MΩ to ensure I had connected this new resistor correctly and I have 10.2MΩ between Pin 8 of V4 (EABC80) and the chassis. __________________ BVWS Member