The troubleshooting tag has no wiki summary.
7
votes
2answers
190 views
How do i test capacitors?
I've just gotten through replacing capacitors on a trio of dead LCD screens (nothing's blown up yet, so far) - they either had one or two capacitors on their inverter circuit SLIGHTLY bloated, and not ...
7
votes
2answers
1k views
Poor eye diagram, where to start looking?
I'm trying to debug a 100Mbit ethernet board and I'm running up against a problem I'm having trouble trying to resolve.
This is the eye diagram for the transmit pair. The receive pair is very ...
7
votes
2answers
145 views
1/2 screen on 1953 Zenith TV
I have been working on a 1953 Zenith TV; I can get raster on the top half of the screen only. If I reverse the leads on the Vertical deflection coil, I get raster on the bottom half only. So far, in ...
6
votes
2answers
983 views
Find short location on PCB
I am trying to find a short on my board. So far, I have used my fluke to measure the resistance to gain some clues but everywhere I measure 4 ohm, so that didn't work.
I am thinking of trying to ...
6
votes
3answers
2k views
How to find a faulty LED in a LED Christmas lights string
I have a LED Christmas lights string, which consists of two circuits of LEDs connected serially. It is working directly on 110V AC. Most LED sockets have 2 wires connected to them, some have three. ...
5
votes
3answers
1k views
Why is SMPS controller IC failing?
I'm back to diagnosing power supply failures, in an LLC resonant SMPS based on the L6598, from a 400 V PFC supply with ostensibly 400 W output. I'm new to SMPS, and learning this all as I go, and the ...
4
votes
5answers
377 views
Troubleshooting a broken speaker system
First I apologize if this is the wrong place for this question.
Recently my sub-woofer/amplifier stopped working, and I would like to know what is broken. I opened the case and didn't find any ...
4
votes
2answers
566 views
Isolation transformer and scope when troubleshooting SMPS
I have a simple question, when troubleshooting a SMPS is highly adviced to use an Isolation transformer. But my question is this, if im using a scope to troubleshoot the "hot" side of my SMPS, both ...
4
votes
1answer
253 views
Resistor in series with primary side of transformer failing
I was given a Trio CS 1554 Analog oscilloscope. It hasn't been turned on for at least 2 years, but probably a whole lot more.
Today I plugged it in and it turned on. It was usable for approximately ...
3
votes
2answers
277 views
Why did my FM transmitter mysteriously die?
I made a little FM transmitter project a few months ago. I used an Arduino, a litle 4-digit serial LED display, a couple of buttons and an FM transmitter component with breakout board
I had this put ...
3
votes
4answers
1k views
Arduino serial communication fails when stalling/loading a DC motor controlled by PWM
I'm using the following circuit (from http://luckylarry.co.uk/arduino-projects/arduino-control-a-dc-motor-with-potentiometer-and-multiple-power-supplies/) to control the speed of a 6V DC motor powered ...
3
votes
1answer
289 views
How to stop a switched current affecting an IC?
I have 10 circuits each consisting of a Touch IC (Atmel at42qt1010) and electrode, and 2 x 350mA Constant current regulators (NSI50350AST3G) and LED's. All connected to a Arduino Mega, by ~1 meter ...
3
votes
1answer
210 views
FM Transmitter Circuit
I'm trying to make a FM transmitter work properly. I built the following circuit :
I can synchronize with 94.8Mhz channel on any FM radio, I know that because the original sound from that radio is ...
2
votes
2answers
113 views
Why doesn't this (adapted) circuit work with the given power voltage?
I'm helping a little friend with his first project: an electronic dice from Velleman. The circuit is here (click to enlarge):
He built it, I checked and improved it, everything was okay - except we ...
2
votes
2answers
372 views
Weird failure: Loud Sweep Tone on SMPS, ideas?
my brother has an old mac computer that didnt work, so he asked me to fix it, its one of those macs from the early 90s, a Macintosh Classic II.
So i opened it up and i found electrolyte all over the ...
