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

sobell1980 · 19th Dec 2014, 4:14 pm

Yes I think you are right Phil. I think this intermittent poor connection was the main issue, with the valve heater voltage also being low. I can now see where I was going wrong. Investing in the scope and sig gen earlier would have revealed these problems much earlier. I also thought I understood the circuit well, but I'd learned it incorrectly. My understanding of how the tuning coils were part of the circuit etc was my biggest bug bear. To be honest I really enjoyed the alignment which in the end revealed the fault on the coil. I am no expert and have a long way to go in this fantastic hobby. But the purpose of this set was for me to gain this knowledge. I shall contine with the scope on working sets. This will aid my future diagnosis of what I should see where. 2011 I started this set! I have since acquired many other valve sets to continue this hobby. The RMB is being given to my very good friend for Christmas as my first completed valve set. I would like to take this opportunity to thank everyone on here who has had input on this repair and taken the time to mentor me.
Jim, thankyou for the valve sockets and the afternoon in your workshop and lesson on alignment. Also for the boxes of useful valves etc. All of you have been great. When I get time i shall post my success story with some photos. Kind regards.
DAVE.

19th Dec 2014, 4:14 pm	#159
sobell1980 Octode Join Date: May 2011 Location: Bromyard, Herefordshire, UK. Posts: 1,241	Re: Roberts RMB Problems Yes I think you are right Phil. I think this intermittent poor connection was the main issue, with the valve heater voltage also being low. I can now see where I was going wrong. Investing in the scope and sig gen earlier would have revealed these problems much earlier. I also thought I understood the circuit well, but I'd learned it incorrectly. My understanding of how the tuning coils were part of the circuit etc was my biggest bug bear. To be honest I really enjoyed the alignment which in the end revealed the fault on the coil. I am no expert and have a long way to go in this fantastic hobby. But the purpose of this set was for me to gain this knowledge. I shall contine with the scope on working sets. This will aid my future diagnosis of what I should see where. 2011 I started this set! I have since acquired many other valve sets to continue this hobby. The RMB is being given to my very good friend for Christmas as my first completed valve set. I would like to take this opportunity to thank everyone on here who has had input on this repair and taken the time to mentor me. Jim, thankyou for the valve sockets and the afternoon in your workshop and lesson on alignment. Also for the boxes of useful valves etc. All of you have been great. When I get time i shall post my success story with some photos. Kind regards. DAVE.