28-10-2014, 04:57 PM
(This post was last modified: 28-10-2014, 05:03 PM by Radio Fixer.)
Well, alas not mustards Refugee.
It all appears untouched. The crackle that the owner thought was the volume control was HT on a switch contact arcing to the earthed stud. Partly due to dirt but probably mainly silver migration as the contacts and rotors have that blackened silver look. So far I have given it a scrub with a stiff brush and DeOxit and that has stopped it. I will have a closer look later and maybe scrape the wafer with a scalpel or a bent warding file.
Glad it wasn't the volume / tone control as dual gang pots are tricky as often the shafts are special to the knobs !
HT measures high, the high mains input again. The EL84 grid had 4 V + on it. When the coupler cap was snipped the cathode volts and anode current dropped by a third. Wonder how the valve is: will test it later.
See someHunts brown caps ... more inspection needed.
Gary
It all appears untouched. The crackle that the owner thought was the volume control was HT on a switch contact arcing to the earthed stud. Partly due to dirt but probably mainly silver migration as the contacts and rotors have that blackened silver look. So far I have given it a scrub with a stiff brush and DeOxit and that has stopped it. I will have a closer look later and maybe scrape the wafer with a scalpel or a bent warding file.
Glad it wasn't the volume / tone control as dual gang pots are tricky as often the shafts are special to the knobs !
HT measures high, the high mains input again. The EL84 grid had 4 V + on it. When the coupler cap was snipped the cathode volts and anode current dropped by a third. Wonder how the valve is: will test it later.
See someHunts brown caps ... more inspection needed.
Gary
