28-07-2020, 01:03 PM
Quick update.
It developed yet another fault, the audio would fade slightly & become distorted after about 4-5 hours. On the GRAM input this didn't happen which was a relief! Eventually I found the problem, more by accident than anything else. Chassis out on the bench running, switched between MW/LW and back then noticed some arcing/tracking on the monster of a multi way switch, between the metal work of the switch & the paxolin panels holding the leaf switches. Closer examination revealed charring right on the edge nearest the metal work. After about an hour of swabbing with cotton buds & acetone to remove any residue that may be there I ground off the charred paxolin with a dremel like tool. This was then given three over coats of conformal coating. When powered back up the familiar background hissing was almost none existent. I thought I'd done some damage somewhere! When tuned to my pantry TX it was working fine, better than it ever has. Left on all day & no problems at all. I've since found out via the Radiomuseum website that there are two versions of this set, one for AC only (mine) & an AC/DC version, same chassis, same model number but different line up of valves & tuning dial. I'm still working on the final diagrams for this set, once I 've finished & I'm happy with them I'll upload them.
It developed yet another fault, the audio would fade slightly & become distorted after about 4-5 hours. On the GRAM input this didn't happen which was a relief! Eventually I found the problem, more by accident than anything else. Chassis out on the bench running, switched between MW/LW and back then noticed some arcing/tracking on the monster of a multi way switch, between the metal work of the switch & the paxolin panels holding the leaf switches. Closer examination revealed charring right on the edge nearest the metal work. After about an hour of swabbing with cotton buds & acetone to remove any residue that may be there I ground off the charred paxolin with a dremel like tool. This was then given three over coats of conformal coating. When powered back up the familiar background hissing was almost none existent. I thought I'd done some damage somewhere! When tuned to my pantry TX it was working fine, better than it ever has. Left on all day & no problems at all. I've since found out via the Radiomuseum website that there are two versions of this set, one for AC only (mine) & an AC/DC version, same chassis, same model number but different line up of valves & tuning dial. I'm still working on the final diagrams for this set, once I 've finished & I'm happy with them I'll upload them.
