General > General Technical Chat
Got shocked by a CRT
<< < (6/8) > >>
Halcyon:

--- Quote from: M4trix on January 30, 2021, 01:00:18 am ---Hm, josh132 created this thread 5 days ago. I wonder is he ok ?  :-//

--- End quote ---

According to his forum profile, he was last active today. I'd say he is fine.
james_s:

--- Quote from: helius on January 30, 2021, 12:49:26 am ---I am somewhat leery of the "screwdriver" method, for the reason that the spark may induce high currents in nearby wires or PCB traces. One approach I have used is to use a high-voltage probe with banana plugs and put it into the milliamp jacks of a DMM. The approximately 1 Gohm of the probe will slow the discharge down to a very safe level and it can be simultaneously monitored.

For all the talk about CRT discharging, a very important safety issue is usually overlooked, which is that the power supply section of the monitor chassis has much more dangerous capacitors. With 250VDC and thousands of uF, they can in fact kill you. The same caution needs to be exercised as with all mains connected power supplies. If there are no bleeders or they are open circuit, you need a way to discharge these caps before working in the PSU area.

--- End quote ---

Well it's anecdotal of course, but I've been using the screwdriver with a length of plain wire method for ~30 years on hundreds of different CRT displays and never had any issues with it but YMMV. The friend who taught me how to repair monitors worked in a repair shop back when those were a thing still and that's how they did it too.

You're absolutely right about the power supply. People tend to fear the EHT and overlook the fact that the "low" voltage in the power supply is a lot more dangerous. One of the worst shocks I've ever had was from the bulk filter capacitor in an Electrohome G07 monitor. Those have a dangerous failure mode where a bad flyback transformer or HOT blows a fuse that is on the *output* of the B+ supply and the result is a large electrolytic capacitor charged to 170V with no load to discharge it, only the internal leakage of the capacitor itself.
james_s:

--- Quote from: M4trix on January 30, 2021, 01:00:18 am ---Hm, josh132 created this thread 5 days ago. I wonder is he ok ?  :-//

--- End quote ---

Probably got the answer he came here for and left the thread.
S. Petrukhin:
Hey, josh132! Guy, people are worried! Let us know how you feel!
rsjsouza:
Well, he is apparently fine judging by his other post...

https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg3545073/
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod