This was a very common trick used specifically in cases of badly worn out cathode ray tubes of TV sets, either blackwhite or colour. Apart from that, the application of a high voltage pulse was the next action, usually between the cathode and the 1st grid, which was causing the burn out of the dead cathode material, leaving its fresh one do its job...This (rejuvenation procedure, as it was called) was both a money saving job for the customer and a money making job for the repairs technician, since such a successful procedure was cost effective and it could last for some years more of added life for the tired CRT, avoiding its immediate replacement...
exactly, i even got one of them TV repair shop portable CRT regenerators stocked :-) maybe i make a video about it one day, the only problem is, i dont have a tv set with crt, so i cant make a real test and demonstration.
the resistors also work as current protection, while a mA meter will blow up once to get faulty tubes, and you can now measure it all using only one meter, simply swap between the two resistors, the other part is still loaded and still stable. much better solition
@@Master_zzz you sure can, then you get both the current readout and the protection needed from the resistor.. or simply measure voltage and divide by the resistor value it is over to reveal the current, if that is important, I dont really care what the current is, as long as it is the same and with in the range I have explained in the video, then the chance that tube is ok is very high. There are many other parameters this quick and simple tester dont reveal, but most people dont need all that to repair an old instrument.
Hi Thomas, Brilliant thanks.. Question I have a ecc83 which measures 109v 138v, and 250v, 250v when heaters are off. does this mean super gain or a fault?
nominal is 145V if you read a bit less DC gain point is a little bit higher, but you also see 30% difference between the two triodes, same numbers = better, and the closer to 145V the better normally, but your tube could be working fine in many constructions, where correct DC and AC local feedback is used, it is also a good sign to see 250V with heater off = no leakage at least in the anodes you could also make a leakage tester to any - from any, of the other parts, this is tested with cold filaments, and all should be "open"
good morning. i am an ignorant enthusiast. i don't understand where you got normal voltage values of the plates. could i have the values for ecc88/6dj8, 6922, 6sl7 and 6sn7? many thanks for your excellent work
Hello, you can calculate the anode voltage from the tube datasheet, but it requite a bit complex math, so i cheated, I setup my AVO tester, then i find a few perfect tubes that match perfect values, then i plug the tubes into my simple tester and tell you the voltages, Good values for ECC88 6DJ8 6922 E88CC (all the same values) updated in Description, Note a little bit different pinout. the 6SL7 or 6SN7 are also interesting audio amp tubes to play with, but they use a much different socket, i am not going to play with them right now.
not really needed for my usage, I can just take my AVO if I like to measure all parameters. the consept of this video was to make something fast and simple, that could test if a stock is likely to work, all the tubes that dont passe this simple tester, needs to be thrown out, the ones that pass, can be deeper investigated on parameters neede for what ever unit the tube go into.. not all circuits require good leakage numbers.
@@TeardownOZ2CPU your video succeeded and your circuit is brilliant. I can't wait but one together myself. I'm currently looking at online marketplaces for power supplies that I can cannibalize for a more permanent setup. Again, brilliant! Thank you very much for this information.
@@BlingFreeJ you can take two small transformers and connect them back to back, this way : first : 230V to 6V use this 6V to filament, and then a similar transformer reversed 6V to 230V, you then get your high voltage using two standard parts.
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This was a very common trick used specifically in cases of badly worn out cathode ray tubes of TV sets, either blackwhite or colour. Apart from that, the application of a high voltage pulse was the next action, usually between the cathode and the 1st grid, which was causing the burn out of the dead cathode material, leaving its fresh one do its job...This (rejuvenation procedure, as it was called) was both a money saving job for the customer and a money making job for the repairs technician, since such a successful procedure was cost effective and it could last for some years more of added life for the tired CRT, avoiding its immediate replacement...
exactly, i even got one of them TV repair shop portable CRT regenerators stocked :-) maybe i make a video about it one day, the only problem is, i dont have a tv set with crt, so i cant make a real test and demonstration.
Why are you measuring the anode voltage instead of putting a mA meter in series with the 100k resistors?
the resistors also work as current protection, while a mA meter will blow up once to get faulty tubes, and you can now measure it all using only one meter, simply swap between the two resistors, the other part is still loaded and still stable. much better solition
@@TeardownOZ2CPU If you put the mA in series with the 100k resistor you can measure the current flowing thru the tube.
@@Master_zzz you sure can, then you get both the current readout and the protection needed from the resistor.. or simply measure voltage and divide by the resistor value it is over to reveal the current, if that is important, I dont really care what the current is, as long as it is the same and with in the range I have explained in the video, then the chance that tube is ok is very high. There are many other parameters this quick and simple tester dont reveal, but most people dont need all that to repair an old instrument.
Hi Thomas, Brilliant thanks.. Question I have a ecc83 which measures 109v 138v, and 250v, 250v when heaters are off. does this mean super gain or a fault?
nominal is 145V if you read a bit less DC gain point is a little bit higher, but you also see 30% difference between the two triodes, same numbers = better, and the closer to 145V the better normally, but your tube could be working fine in many constructions, where correct DC and AC local feedback is used,
it is also a good sign to see 250V with heater off = no leakage at least in the anodes
you could also make a leakage tester to any - from any, of the other parts, this is tested with cold filaments, and all should be "open"
good morning. i am an ignorant enthusiast. i don't understand where you got normal voltage values of the plates. could i have the values for ecc88/6dj8, 6922, 6sl7 and 6sn7? many thanks for your excellent work
Hello, you can calculate the anode voltage from the tube datasheet, but it requite a bit complex math, so i cheated, I setup my AVO tester, then i find a few perfect tubes that match perfect values, then i plug the tubes into my simple tester and tell you the voltages,
Good values for ECC88 6DJ8 6922 E88CC (all the same values) updated in Description,
Note a little bit different pinout.
the 6SL7 or 6SN7 are also interesting audio amp tubes to play with, but they use a much different socket, i am not going to play with them right now.
@@TeardownOZ2CPU thank you very much.
Does the tube recover its emission for a long time ?
It could be an interesting way to renew old tubes.
The result vary from tube to tube, and how you perform it, double the filament, and the anode current, for 1 to 10 mins is normally the trick
Any more thoughts on adding leakage testing to the circuit?
not really needed for my usage, I can just take my AVO if I like to measure all parameters. the consept of this video was to make something fast and simple, that could test if a stock is likely to work, all the tubes that dont passe this simple tester, needs to be thrown out, the ones that pass, can be deeper investigated on parameters neede for what ever unit the tube go into.. not all circuits require good leakage numbers.
@@TeardownOZ2CPU your video succeeded and your circuit is brilliant. I can't wait but one together myself. I'm currently looking at online marketplaces for power supplies that I can cannibalize for a more permanent setup. Again, brilliant! Thank you very much for this information.
@@BlingFreeJ you can take two small transformers and connect them back to back, this way : first : 230V to 6V use this 6V to filament, and then a similar transformer reversed 6V to 230V, you then get your high voltage using two standard parts.
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