Hi, I'm always in awe of how beautifully crafted those devices were. The additional cover box will most likely be an attempt to stabilize the temperature by creating a microclimate around the tube. That rectifier flashed nicely. Nice day 😶 Tom
Easy enough to take those 2 EF50 tubes and run them with 8VAC for a few hours, to wake the cathodes up. Rectifier is easy to replace with a solid state diode though, no real extra work other than the 2 1N5407 diodes and the 2 33R 2W resistors.
looks like one of the smoothing electrolytic caps shorted or developed too much leakage and killed the rectifier....was to be expected....also i see a black tar paper cap by philips and they are always zero ohms shorted....probably you killed several tubes while playing with the device...those type of test gear usually have very little use in terms of hours unless they were used in a big workshop and kept running all day wich i doubt... i am not a recapping advocate but smoothing caps need alway change when the rectifier is a tube, they are very sensitive to excess current...and the black tar caps always need to go, on some philips tube tvs they are in the filament string to ground and often they short and blow open filaments of tubes...when they are used as coupling they short and overbias the tube making it redplate to death. definetely those items should be atleast checked before extensive use of the device...it should be fine to power it up for some minutes to check output but then once hyou determined it was sorta working it was time for maintenance
Hi, I'm always in awe of how beautifully crafted those devices were. The additional cover box will most likely be an attempt to stabilize the temperature by creating a microclimate around the tube. That rectifier flashed nicely.
Nice day 😶 Tom
Easy enough to take those 2 EF50 tubes and run them with 8VAC for a few hours, to wake the cathodes up. Rectifier is easy to replace with a solid state diode though, no real extra work other than the 2 1N5407 diodes and the 2 33R 2W resistors.
looks like one of the smoothing electrolytic caps shorted or developed too much leakage and killed the rectifier....was to be expected....also i see a black tar paper cap by philips and they are always zero ohms shorted....probably you killed several tubes while playing with the device...those type of test gear usually have very little use in terms of hours unless they were used in a big workshop and kept running all day wich i doubt... i am not a recapping advocate but smoothing caps need alway change when the rectifier is a tube, they are very sensitive to excess current...and the black tar caps always need to go, on some philips tube tvs they are in the filament string to ground and often they short and blow open filaments of tubes...when they are used as coupling they short and overbias the tube making it redplate to death. definetely those items should be atleast checked before extensive use of the device...it should be fine to power it up for some minutes to check output but then once hyou determined it was sorta working it was time for maintenance