I'm new to electronic repair. Trying to troubleshoot a Dell monitor that only has an AC port for power. I'm concerned about safety and not getting shocked. Should I order an isolation transformer and plug in the monitor into that and proceed with testing the board inside? Or should I get a DC power supply and limit the amps and connect the voltage to a pin somewhere inside where 19V DC is first expected? Or both? Thanks.
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isolation transformers dont stop you getting shocked, they make it more dangerous infact
they pass enough current to kill you but they prevent an RCD or GFCI from tripping!
just learn where to NOT put your fingers - like not touching heatsinks because they are often live.
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Then don't measure around while plugged into AC mains.
that may be a good thing, because you are absolutely not shorting something out by accident, while plugged into AC mains. The AC or primary side is the one you have to be real careful.Last edited by CapLeaker; 08-31-2024, 07:58 PM.Comment
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Hi CapLeaker, I definitely would like to avoid having the monitor in AC mains. That's why I'm looking for safety addons or alternative ways to measure when troubleshooting, like a DC power supply. I'm totally new to this so still reading and watching videos how other people do it. Thanks.Comment
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You just have to up your skillset, so you are able to determine in which part (primary AC or secondary DC) of the PSU has trouble. Tricky it becomes a bit with PSU's that have a PFC (power factor correction) circuit.
remember ohms law is very important.
remember 1.414 That is to convert AC to DC. let's say 100VAC x 1.414 = 141.4 VDC
Voltages with a working PFC are 380 to 400VDC on the main filter capacitor. If you see 320VDC for example, the PFC isn't working.
Search some usernames and read some threads here on badcaps. There are some real entertaining threads here.
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Awesome advice and I will remember this. The monitor actually does work but gets vertical lines. I'm watching all kinds of videos now trying to find information on what are all the different voltage rails in there . Basically the very beginnings of understanding monitors.Comment
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Vertical lines first thing to do is going after the tab bonds and clean the LVDS ribbon cable.Comment
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one hand tied behind your back reduces the risk of death .Comment
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Today I remembered it was down there and pulled it out to see what was what.
I checked for continuity and everything checked out.
There was a burned smell and a resistor was replaced with a temporary replacement (see yellow box in picture).
The burned smell is very pungent/acidic and I am not familiar with these vintage electronics to know whether I am smelling the remains of the replaced resistor or... -
Hi everyone,
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This is...05-10-2025, 04:25 AM -
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