Electronics > Repair

Current from Discharging 50Kv Color CRT

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--- Quote from: CaptDon on September 04, 2024, 01:22:04 pm ---There is no point in the wire being insulated to kilovolt or more levels. Worthless advice. First off, the cable SHALL be grounded to chassis or the factory designated point when discharging a CRT of a set that was recently in operation. Secondly, what good does 3KV insulated wire do when you would have 25KV on it in the event you were stupid enough to not connect the ground clip? Any off-the-shelf stranded 300 volt rated insulated wire between 14 and 20 gauge will be absolutely fine. A discharge without a current limiting resistor could possibly damage the connection between the aquadag and the cup. I have never heard of any damage and to my knowledge in tens of thousands of intentional discharges at my father's T.V. repair shop I don't know of any short or long term CRT failures caused by hooking a ground lead to a long thin screw driver and discharging the CRT without current limiting. Most often however, we preferred to discharge with the Pomona high voltage meter which by nature of its physically long internal high voltage resistor limited the discharge current and any potential damage from a high current arc. Some manufacturers specified where the return lead MUST be connected for discharging and I believe it was to the ground straps wrapped around the outer aquadag of the CRT.

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Good points. This jives with my experience in the shop, years ago. I couldn’t count how many CRTs - monochrome and color, that we discharged with just a jumper and screwdriver. I can tell you, that jumper wire was probably no larger than about 16 ga.

My curiosity about how much current is on the wire the moment it’s discharged is simply due to wondering if I should make a jumper with a 10ga wire, after viewing that video. What you’ve said coincides with my experience, though and we never melted the wire, insulation, nor heated it up.

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