Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to rec.antiques.radio+phono,sci.electronics.repair
|
|||
|
|||
Cathode / Heater leakage.
Was I wasting my time , rather than throwing out some ECC83, a 6V6 and some
EL34 and EL84.? All various degrees of C/H leakage causing vibration/tinging sensitivity so useless despite useful gain. All measured 5 to 20 M ohm on C/H insulation test on valve tester. Decided to power the heaters from a bench ps and try C/H leakage with a 500V Megger insulation tester. Increasing the heater volts from normal 6V , for short durations then back to 6 , and monitoring on the Megger. Eventually taking up to 15V for 1 second , no longer orange glow of course, and vey low C/H Megger resistance. Now measuring them for the C/H leakage on the valve tester better than 30 meg (maximum measurable on my tester). -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#2
Posted to rec.antiques.radio+phono, sci.electronics.repair
|
|||
|
|||
Cathode / Heater leakage.
On Dec 21, 10:01*am, Meat Plow wrote:
On Fri, 21 Dec 2007 15:51:52 +0000, N Cook wrote: Was I wasting my time , rather than throwing out some ECC83, a 6V6 and some EL34 and EL84.? *All various degrees of C/H leakage causing vibration/tinging sensitivity so useless despite useful gain. All measured 5 to 20 M ohm on C/H insulation test on valve tester. Decided to power the heaters from a bench ps and try C/H leakage with a 500V Megger insulation tester. Increasing the heater volts from normal 6V , for short durations then back to 6 , and monitoring on the Megger. Eventually taking up to 15V for 1 second , no longer orange glow of course, and vey low C/H Megger resistance. Now measuring them for the C/H leakage on the valve tester better than 30 meg (maximum measurable on my tester). CRT rejuvenators *did something similar but the theory was to strip dead material off the cathode. That was to expose new fresh cathode material to increase the emission of the electron guns, I used them many times in the 1950's and 1960's when TVs were much more expensive and people would do almost anything to keep a set running. It was not to reduce/change/eliminate any heater to cathode leakage. There were special 1:1 filament transformers available to use with CRT's that had H-K leakage, these transformers were specially wound to minimize capacitance between the windings so that if video information was fed to the cathode, the signal was not degraded by the windings of the special filament transformer and there was no leakage to the heater. Bob Hofmann |
#3
Posted to rec.antiques.radio+phono,sci.electronics.repair
|
|||
|
|||
Cathode / Heater leakage.
|
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Corroded hot water heater valve leakage | Home Ownership | |||
Cold cathode | Electronics Repair | |||
Testing Fluorescent Tubes for Cathode Emission | Electronics Repair | |||
Cold cathode lamp? | UK diy | |||
Need info: Brimar D7-200GH cathode ray tube | Electronics Repair |