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| Spark while discharging 128K flyback |
Posted by: falen5 on 2024-09-19 16:23:55
Camera rolling while working on the 128k caught this lovely sight
This is the flyback of a Plus analog board that I just transplanted onto this 128K analog board.
There were actually 3 sparks but what ever way youboob compresses video I only see the first
So this 'tiny' , 'harmless' looking spark is the one that can kill you ?
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Posted by: falen5 on 2024-09-19 18:12:18
Meant to say "This is the flyback FROM a Plus analog board that I just transplanted onto this 128K analog board |
Posted by: LaPorta on 2024-09-19 18:37:40
Looks like it shorting to the tube itself...is the dielectric grease no longer present under that suction cup? |
Posted by: dv- on 2024-09-20 06:46:54
Neat. |
Posted by: 3lectr1cPPC on 2024-09-20 08:03:34
I finally got a spark discharging a laptop power supply I was recapping - but on the two smaller output caps, not the large one on the HV side, which surprised me. |
Posted by: cheesestraws on 2024-09-20 08:05:41
bzzt. |
Posted by: LaPorta on 2024-09-20 08:11:07
I've never gotten a spark...but at leas two times I had tetany of my fingers by putting my thumb on one side of the mains on a Plus AB, and my index finger on the other, creating a nice U-shaped path for the electricity. I had to physically pull my arm away because the finger muscles were in tetany from the electric current, so I couldn't release them. |
Posted by: joshc on 2024-09-20 08:27:51
You only tend to get a spark on the pre-SE compacts because there's no bleed resistor. It's sort of nice because at least you know it's definitely discharged when you've seen/heard that spark. |
Posted by: falen5 on 2024-09-20 11:10:56
All the machines from the SE onwards have a bleed resistor but I ALWAYS discharge them - dont know if the bleed resistor is working on them - but as for the original question, that spark is the high voltage right ? and could be enough to throw you across a room , blow a finger off or even kill you - they are some of the stories ive heard over the years - Heard of a tv repair man ( bout 30 years ago ) that apparently has his thumb blown off from a flyback .......... can any of these things be possible from that 'little' spark ? |
Posted by: cheesestraws on 2024-09-20 12:44:09
the physical size of the spark you can see isn't a particularly good guide to the amount of energy being transferred in it |
Posted by: falen5 on 2024-09-20 12:59:34
hi cheese - I know it has thousands of volts , it just 'sounds' small - I once sheered a 3 phase cable in a factory with fork lift - blew me and the 5 ton lift into the air and the noise of it was terrifying - accidently shorted an electric forklift battery once while refitting straps , again the sound was terrifying - worked in place once with an electric arc furnace ....... OMG the noise of that thing was horrific , end of world kinda sound !!! but this little spark 'sounds' so small ....... again you wont see me taking any chances with it , i dont even jab the wire in with my hand , i use a pliars to shuv the wire into the anode ......... how many volts are coming from that flyback anyway , 10,000 volts ?
I fixed the 128K on the other post below - i swapped out the 128K flyback with one from a Plus - put a load of pictures of the blown flyback - scary stuff |
Posted by: AndyMc1280 on 2024-09-20 13:19:14
hi cheese - I know it has thousands of volts , it just 'sounds' small - I once sheered a 3 phase cable in a factory with fork lift - blew me and the 5 ton lift into the air and the noise of it was terrifying - accidently shorted an electric forklift battery once while refitting straps , again the sound was terrifying - worked in place once with an electric arc furnace ....... OMG the noise of that thing was horrific , end of world kinda sound !!! but this little spark 'sounds' so small ....... again you wont see me taking any chances with it , i dont even jab the wire in with my hand , i use a pliars to shuv the wire into the anode ......... how many volts are coming from that flyback anyway , 10,000 volts ?
I fixed the 128K on the other post below - i swapped out the 128K flyback with one from a Plus - put a load of pictures of the blown flyback - scary stuff This is why I got you to do the SE/30. Not yer forklift levels of shorting but even this going bzzt I'd crap myself !! 😳 |
Posted by: dv- on 2024-09-20 16:16:51
the physical size of the spark you can see isn't a particularly good guide to the amount of energy being transferred in it I heard somewhere (maybe a YouTube video about residential electrical work? I deep dived a bunch of those after I got my house) that the voltage/amperage required to screw with your heart is too low to show a visible spark/arc in most situations. So I tend to figure if you can see it you should avoid it.
I know there are exceptions and it’s more complicated than that but it still seems like a good rule of thumb. |
Posted by: 68kPlus on 2024-09-20 16:38:42
Dang. I've never had a flyback spark on me before, I always wait too long or it has a bleeder installed. |
Posted by: LaPorta on 2024-09-20 17:03:27
I always do the screwdriver-under-the-cup thing no matter what. |
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