09-05-2022, 11:09 AM
(This post was last modified: 09-05-2022, 11:10 AM by Mike Watterson.)
Replaced twin unmarked mains lead with light-weight 3-core mains with blue, brown & yellow/green cores. Live to switch terminal on fuse & tag board and neutral to common of voltage selection fuses. The tag board a bit cooked at bottom likely due to he screen cap (just under it) burnt by 1300 Ohm resistor burnt out (one end to Audio TX on tag, other end to EL84 Screen Grid / secondary HT. I have that resistor differently mounted now. That's the same wiring for mains as when I reversed the cable at the plug which improved LW. Adding an earth makes LW worse, common.
Often radios with live chassis and single pole switch on the volume control have switch to chassis to reduce hum. Wires here from tag board with fuses to switch are a twisted pair. No noticeable change in hum with live to switch on this set.
Final Tally
9 paper caps removed and replaced. One between volume slider and EABC80 triode grid got cut at valve base and a 0.1uF ceramic fitted as it was too difficult to remove. Other caps on tone controls left as no HT etc.
1 Electrolytic replaced, a 4uF 80V on FM discriminator with 2 x 2.2 uF 100V in parallel. The +ve to chassis.
25 Ohm that was retrofitted between earth tag and screen grid tag of EL84 removed. The tag with the audio transformer winding is nearby, so obviously fitted in error to replace the burnt out 1300 Ohms. I put the 25 Ohms in series with the silicon bridge someone had fitted instead of original "metal rectifier" (probably typical German selenium type).
Fitted 1000 Ohms on unused tag near secondary HT 50uF cap tag and other end to yellow audio transformer wire with heatshrink sleeve. Add 100 Ohms between tag and 50uF +Ve tag. The total 1100 Ohms is close enough to the original 1300 for secondary HT line and EL84 Screen grid.
Refitted VHF drive cord and treble flag drive cord. Neither broken, just off.
Refitted loose part & bulb of the AD switching lamp at rod rotation knob.
Freed up seized AD switch push-on/ push-off switch (Ferrite rod or socket).
Wiped case and picked off gratuitous clear sticky tape.
Replaced two core flex by three core and earthed chassis.
Often radios with live chassis and single pole switch on the volume control have switch to chassis to reduce hum. Wires here from tag board with fuses to switch are a twisted pair. No noticeable change in hum with live to switch on this set.
Final Tally
9 paper caps removed and replaced. One between volume slider and EABC80 triode grid got cut at valve base and a 0.1uF ceramic fitted as it was too difficult to remove. Other caps on tone controls left as no HT etc.
1 Electrolytic replaced, a 4uF 80V on FM discriminator with 2 x 2.2 uF 100V in parallel. The +ve to chassis.
25 Ohm that was retrofitted between earth tag and screen grid tag of EL84 removed. The tag with the audio transformer winding is nearby, so obviously fitted in error to replace the burnt out 1300 Ohms. I put the 25 Ohms in series with the silicon bridge someone had fitted instead of original "metal rectifier" (probably typical German selenium type).
Fitted 1000 Ohms on unused tag near secondary HT 50uF cap tag and other end to yellow audio transformer wire with heatshrink sleeve. Add 100 Ohms between tag and 50uF +Ve tag. The total 1100 Ohms is close enough to the original 1300 for secondary HT line and EL84 Screen grid.
Refitted VHF drive cord and treble flag drive cord. Neither broken, just off.
Refitted loose part & bulb of the AD switching lamp at rod rotation knob.
Freed up seized AD switch push-on/ push-off switch (Ferrite rod or socket).
Wiped case and picked off gratuitous clear sticky tape.
Replaced two core flex by three core and earthed chassis.
