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.
-
-
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.
-
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
-
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
-
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.
Comment
-
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
-
Vertical lines first thing to do is going after the tab bonds and clean the LVDS ribbon cable.Comment
-
one hand tied behind your back reduces the risk of death .Comment
-
Picked up a Tektronix type 422 oscilloscope locally for a few bucks last year.
It wouldnt power on at all so I stowed it away under my bench for later testing.
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 all. I need to replace an SMD fuse on my camcorder and this is the first time I have had to do any SMD soldering so your advice would be appreciated. Below is a picture of the board that I am working on and I have highlighted the fuse that needs to be replaced. I managed to zoom in to take this picture but the fuse is really tiny and is sandwiched between other components so this is going to be a new milestone for me. I appreciate that I am going to have to buy a new soldering iron if you could advice on what I need please. I was thinking about putting a big soldering iron across the whole... -
Hi everyone,
I'm working on repairing a Pilz PNOZ X4 safety relay module. When I opened it up, I found some of the connector pins detached from their pads. I replaced the connector with individual wires, but the issue remains.
The module is set to dual-channel mode with manual start. In this mode:- Y36-Y37 and Y1-Y2 are bridged.
- 24VDC is applied across A1-A2.
- It monitors two emergency circuits (S11→S12 and S11→S52).
- When both are closed (24V present on S12 and S52) and the start button is pressed (S33 connected to S34), the NO contacts (13-14, 23-24, 33-34)
-
I’d appreciate some very basic advice on CH341x programmers. I know this topic comes up from time to time, but stuff changes, so I hope a refresh is in order. In particular, I see some unexpected things happening with jumper positions.
[My plan is to learn to read and write 24CO2 EEPROMs via I2C. The first target is the one in my Uni-T clamp meter, but before tackling that I have some brand-new EEPROMs to practice on.]
I have two basic Chinese programmers. One is the blue board with a CH341A and two rows of pin headers. To my untrained eye it looks like all the others.... -
Hi all,
I made a big-ass mess here of my father's beloved P602, and I'm trying to figure out if I should order a batch of overpriced ribbons or if I'd just be throwing more good money at the bad.
He woke up recently to a bunch of white bars going down the right side of the screen. From what I'd seen in these places, I figured the T-con board has gone out or has a bad connection. I took the back off and gently poked at the socketed ribbons and sure enough, got the image back. It was mainly the far left ribbon, and it would snap back to stripes if I let off the pressure....
Comment