So for context, my CRT TV identifies as a grayscale CRT, despite being born a color TV. I want to for the 100th time take it apart and see if there's anything sus looking that I replace or reflow the solder on in the hopes of fixing it. I got sick of discharging it via screwdriver so I made this....thing.
Will dumping a bunch of electricity down the earth pole of an outlet flip the main breaker (considering that only ground is connected)? My electrician friend was kinda unsure about it, I think he said something about the breaker measuring the diff between neutral and earth and as neutral isn't connected it might be fine.
t. moron who repairs his electronics but doesn't know anything about electricity
No, it shouldn't trip the breaker. If you have a GFCI on the circuit you discharge to then it might trip. Even if it does, just reset it. If your wiring is properly grounded you'll be fine.
You do know that instead of a plug you could've attached an alligator clip to the end and clamped it onto anything metal that's grounded right?
Ok, thanks!
>alligator clip
Sure, but I had a bunch of spare plugs and no alligator clips so this was cheaper to do.
Haha, this is just a small CRT monitor that I have hooked up to my Commodore 64, amongst other things. I actually prefer the way colors look on CRT over LCD, but my other monitors are LCD, for obvious reasons.
>If you have a GFCI on the circuit you discharge to then it might trip.
It shouldn't. GFCIs measure the difference between hot and neutral and trip if there is a difference of 5mA.
t. IBEW electrician
>and trip if there is a difference of 5mA.
Now that depends on the breaker characteristics doesnt it. European standard is 30 mA but you can also get 300 mA. 5 seems quite low. But then you yanks do moronic things with electricity all the time anyway.
t. REAL 230V chad electrician.
Apparently yours is called an RCD. The reason we use 5mA is because we want to stop any damage being done to a person while you guys have the mentality that it's fine to cook your internal organs and leave scarring all across your vital viscera as long as it doesn't cause your heart to stop in that exact moment.
>CRT TV identifies as a grayscale CRT, despite being born a color TV
jesus what year is it
as long as the tv isn't plugged in it will be fine.
current imbalance protective devices like GFCI operate on a difference in current detected between line and neutral, you aren't connecting anything to either of those.
if your tv was plugged in and charging the cap when you short it then some of the line current would leak to earth and it would trip a GFCI.
overcurrent protection typically is on line only, not ground. so that won't trip either.
you put some impedance in that thing right? put a couple megaohms in it and it won't bang when you use it, but you have to hold it on for a couple seconds.
>you put some impedance in that thing right?
Uhhhhhhhhhh nope. I was actually considering it but decided I lack the electrical knowledge to try and would rather be certain it Just Works (TM).
How would I go about doing that? Resistors? A lightbulb? I feel like I'd need something more beefy than the tiny hobbyist through-hole resistors I've got, but maybe that would be fine since it's just going to have power for a couple of seconds.
In case this is of any importance - the "crt anal probe" was made from a tent stake (that I've tested actually conducts electricity), and a stranded copper wire that I've wrapped and soldered around the tent stake hook. The solder job might be suboptimal as it was hard to heat the tent stake enough with just my tiny soldering iron - I ended up using candles to heat an area close to but not at where I was soldering, in order to up the temperature but not contaminate the soldering area, and I also used a ton of flux/soldering grease. The solder job should stick, if it doesn't I'll have to come up with some better way to solder this.
Oh and I also filed and roughed up the area I was soldering to, in order to remove the top layer of metal and increase the chances of it sticking and making good contact
Picrel is without electrical tape
Since PrepHole came into being as a board about manga and anime, i can't help but envision a shy and frightened little CRT monitor standing on a desk and, while looking at that device in horror, asking timidly in a japanese schoolgirl manner:
"y-y-you want to put THAT...WHERE?!?!?!"
"...
...shuddup b***h and bend over"
xD
BWAHAHAHAHAH NOIOOO
Just use something a like a 5K ohm resistor to discharge the high voltage in the caps, or any sensible value for that matter. They won't fry unless you use something moronic like a 10 Ohm 1/4W resistor.
ok lets work out an example.
say your flyback is 20kv
power = current * voltage, for a 1/4w resistor:
current = 0.25/20000 = 12.5uA (max continuous current)
resistance = voltage / current = 20000/.0000125 = 1600Mohm minimum
so extremely unhelpful for an impulse discharge, you would need some integration of the capacitance and the heat dissipation of the resistor to work it out properly.
if you know the power and impedance of a lightbulb you can work out the same way if it will burn out or not.
i said add a resistor to stop it from discharging too quickly which puts extra strain on the whole circuit and makes a loud scary noise.
waiting a couple of second != waiting ??? hours for it to discharge itself. good troll lol.
Thank you <3
No idea who that is.
1. Lol I've done this before and I've been fine, I just wanted a slightly more proper tool than a screwdriver with copper wire wrapped around it.
2. Yes, but this CRT is special to me 🙂
3. I've tested with other input sources and it's broken on those too. I remember one time when it had been on for hours it flipped to color mode, probably because it got warm enough, so I know it can do it. There is a button on the front that has something to do with color, but no visible change happens when I press it, so I want to see if there's anything funky going on on the PCB near said button. I've already tried cleaning and resoldering the PCB that is responsible for input, and that didn't change anything except maybe improve signal to noise ratio ever so slightly.
The TV isn't even grounded through its plug, the plug has no ground. If the TV Is grounded at all that'd be through the antenna cable I suppose. Besides, I'm not doing this whilst it's turned on or plugged in, that'd defeat the whole point.
>you put some impedance in that thing right? put a couple megaohms in it and it won't bang when you use it, but you have to hold it on for a couple seconds
>OP doesn't want to wait for discharge so he makes a plug to do it fast
>hurr durr you should add a resistor and wait for it to discharge
PrepHole everyone
bait/troll?
I have nothing against adding a resistor, I was just uncertain how to best do that and what to use. My knowledge about anything electricity related is effectively zero, I just like doing simple repairs and mods to my things.
what are you discharging to be exact?
just the cap on the top of the crt monitor? I've just used 12 gauge wire and grounded it to the metal frame of the TV, that was for my "oscilloscope" project before it got thrown out when i was a kid.
Yeah, I just don't wanna get zapped or accidentally zap anything when working on it
Do you watch Shango066 repair TVs?
1. I was to see OP fry himself as much as anyone
2. Aren't there still free CRT listed all the time?
3. How does OP know it's the crt and not the c64, cable, or settings?
You have to connect the other end of the probe to a grounded part of the TV, not to earth. The TV will be floating with respect to earth unless it's plugged in and there won't be a path for current to flow.
Ideally you short the capacitor across itself but since op is at earth ground potential he can short the hv side to earth ground potential and touch it safely. It works because the earth acts as a giant capacitor and charges until the charges in cap and planet are relatively charged effectively the cap charge will be zero.
OP here, anyone has any suggestions as to what the second marking below AUTO COLOR could mean? I think it says AFT.
I've resoldered two somewhat sketchy points, but besides that I can't find anything obviously wrong, everything is in such good condition it looks almost factory new.
OP again, color now works 🙂
Sick
proud of you anon, glad you didnt let it go to waste
was resoldering the final fix?
I did re-solder a few spots that looked bad, but generally the TV is in almost factory new condition internally, so I don't think that's what fixed the issue.
I had to adjust a couple of trim pots to get it to recognize color over composite input, and I did this whilst it was turned on so I could visually observe for changes and ensure I didn't mess anything up in the process.
Somewhat amusingly, doing this whilst the TV was powered on rendered my grounding rod (that I spend an afternoon on making) fairly useless, as the intended purpose of it was to ensure I could safely touch the TV whilst it was off; it's of no use when the TV is on.
Proud of you anon. It’s rare to see a PrepHole poster actually do something, and even rarer that they are successful.
>My electrician friend was kinda unsure about it, I think he said something about the breaker measuring the diff between neutral and earth and as neutral isn't connected it might be fine.
Your electrician friend is incompetent. A breaker trips when too much current is going through the hot (line) wire. He's thinking of a GFCI.
I'm not familiar with CRTs, but if the power is stored in large capacitors, you can discharge them with a large resistor.
No, power is stored in the balls.