Questions tagged [troubleshooting]
For questions about troubleshooting circuits. Please note that repair questions must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being repaired.
324
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How to determine whether a transformer is dead
My range hood broke, so I took it apart. I confirmed that 125V is arriving at the control board, which is connected to a fuse which is good, which is connected to a transformer. My voltmeter (AC mode) ...
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High voltage vanishes when increasing AC current on an X-ray supply
I have an old high voltage X-ray power supply enclosed in a pit of insulation oil that is difficult to operate on. The supply includes both a high voltage transformer with dual star connected ...
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New XLR + Audio Interface slight static noise [closed]
I am very new to XLR and audio in general. This is a simple set up to record my voice to OBS.
I purchased an audio-technica at2020 with a Depushung M4 audio interface (all very new to me) and after ...
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64
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Diagnosing Issue in Bench Power Supply with Buggy Display
I have a BK Precision 1660 Power Supply with a buggy display. The system has two displays (master and slave), the slave display working perfectly fine while the master display will sometimes flash ...
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86
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Vintage Intercom BJT Preamplifier: Purpose of Capacitors and DC Bias Troubleshooting
EDIT - Further Research - Comments on Common Emitter Preamplifier
https://sites.google.com/a/davidmorrin.com/www/home/trouble/transistors/amplifiers
The preamplifier stage in the circuit below has ...
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114
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Testing out a bridge rectifier if it works with only a multimeter
Indulge me here with this scenario, but suppose the electronics shop I'm sourcing parts have dubious, faulty semiconductors parts -- damaged, counterfeit, etc. What have you.
How do I test if a bridge ...
- 263
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2
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46
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Troubleshooting inaccurate resistance readings in SMD resistors on PCB
My PCB has high-precision SMD resistors (0.01%, 25ppm/C) - some pre-installed, some I added. When I measured their values in-circuit with a multimeter directly at the pins, some of them showed ...
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154
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Measuring 240v 3-phase circuits with an oscilloscope
I have an injection molding machine that has some odd behavior* going on in it which I need to diagnose. I've probed around with a multimeter, but I think I need to understand deeper what is happening....
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Troubleshooting an Electrical Circuit - Is This an Expected Voltage Drop?
I am troubleshooting an electrical problem and am having trouble understanding the readings I am seeing on my digital multimeter. I am a DIYer with just the basics of electrical engineering knowledge,...
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Minimizing small signal relay bypass pop
Attached is a stripped down version of the circuit. The relay is controlled by a push button going to a microprocessor then powered by a BJT with a flyback diode in parallel.
The output of the DSP/etc....
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Ladder Logic - Recognizing Pattern Failures
(First Post Here)
Something I want to look into adding to a production process is being able to recognize the same failure (that's in a pattern) and having the machine give an alarm once it sees the ...
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In testing this op-amp, I always get same amplification. Did I break it?
I bought these TL072 (maybe TL072CD) IC amps, for a circuit I was trying to build, but the circuit wasn't working at all so I tried to troubleshoot the amp.
I built a voltage divider ~1/1000 (on the ...
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72
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How to diagnose a possibly failed crystal?
I'm trying to repair a Panasonic SA-PMX70 audio system and I have narrowed the issue down to a DAC/DSP IC ("BU9447", proprietary, undocumented) which does not seem to be responding at all. ...
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How to isolate multiple 24 VAC to 5 VDC power supplies (buck converters) that are all powered by a single main transformer with a common pole?
Basically, I am trying to test multiple relay controlled outputs that are all 24 V outputs. One pole of the transformer is going into a relay for each device and the other side of each device is ...
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Opamp overheating in analog circuit
I'm fairly new to designing circuit boards. I have built a circuit in EasyEDA that takes a 0-3V3 PWM signal from a Teensy4.1 MCU and converts the signal to 0-20 mA current using a low pass filter and ...
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378
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How to improve the performance of my low pass filter design
Goal:
I am designing a low-noise, 8-pole, low pass filter to use in the output stage of a lock in amplifier. The filter needs to attenuate wide-band noise and a doubled carrier frequency in the range ...
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Troubleshooting class AB amp with only multimeter
I made a stereo amplifier on a PCB which is two of the following circuit.
One channel amplifies the audio decently, but the other channel has NO sound regardless of how loud I make the input.
My sound ...
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How to reverse the behavior of a thermistor?
I have an NTC thermistor that reduces its resistance when temperature increases, but I need a circuit where resistance increases. Without using a different thermistor (or a microcontroller), is there ...
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Troubleshooting servo issue on custom PCB
There is an issue on my custom ESP32 PCB board. One of its features is to control a very high torque hobby servo motor (this one). The PCB works perfectly with a bench power supply but not with a ...
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Diagnosing single phase 3-speed brushless AC motor
The air conditioner Family FSA-15H has one-phase fan brushless AC motor with 3 constant speeds: High, Medium, Low. After 2 years of rare use, the fan works only on ...
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Issues with I2C from MCP23017on Arduino
I am trying to use the MCP23017 expander chip with a Metro Mini by Adafruit (pinout below) and I can't get the microcontroller to connect reliably via I2C.
update
I connected the RESET pin to 5V and ...
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163
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Voltage Drops to 0 When Load is Connected [closed]
I have put together a simple voltage regulator that uses an LM338 IC and a potentiometer to adjust the voltage. On the output, I also put an inline 3A fuse to protect it from overloading.
(the diagram ...
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LED driver current consumption issue
I have an LED driver circuit that is not behaving the way I expect it to. More precisely, it’s not drawing as much current as I expect it to do. The design is not originally mine, so I don’t know the ...
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Help testing Pressure Sensors
I have a few ME600 Metallux sensors that I harvested from some discarded products. I want to build a project with these but would like to verify they work before getting too far. From the datasheet ...
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270
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Help Testing ATX PSU 8 Pin PCIE Connector
I'm trying to do some pin swapping on an 8 pin PCIE power cable. It didn't come with my PSU, so I know it's probably not going to work how it is. I've done research on how to test and swap the pins ...
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How to increase a mic output level?
I have an old lapel mic that outputs a signal that is way too small for most applications. In my attempts to learn electronics I started analyzing it and reading about the subjects. Still, I'm left ...
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Fix for poorly designed class-D amplifier mute circuit
I recently made a PCB for a project with several class-D amplifier channels to drive small speakers for audio feedback. I included a mute switch which connected or disconnected one end of these ...
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Single-supply op-amp (LM324A) output does not change
I am trying to create a non-inverting op-amp circuit using one of the op-amps in the LM324AN IC. Part of the requirements of my project is that I must tie VCC- to ground, so I am operating in single-...
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Digital Counter not initializing to 0 or rolling over to 0
I'm trying to make a 3-bit counter using D flip flops that loops through the sequence (0,3,4,5,7) repeatedly.
So far, I've made a timing trace, block diagram, operation table, Karnaugh maps, rough ...
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Why is connecting an analog servo distorting this PWM-wave?
I'm working on a project where I'm trying to steer an analog servo using a PWM-wave generated by this circuit. I found the circuit design from this article. It consists of three operational amplifiers ...
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Why does touching the Rx line cause my XBee to reset?
I have an XBee, XB3-24Z8CM-J, in MicroPython mode, autostarts script on boot, 115220 baud, UART is enabled on Pin 4 & 5.
The issue is that when I touch pin 4 (Rx) while the script is running the ...
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Lamp transformer fix makes monitor shut down
I fixed a lamp transformer case (230 V to 12 V) by making a 3D printed one. I measured 12 V at the secondary coil and the lamp is working well.
The thing is, when I plug the transformer to a power ...
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Heating element testing - calculation
I have a 3-phase, 30 kW, 480 V AC heating element.
I’m trying to utilize resistance as an aid for predictive failure.
Using Ohm’s law calculation
480 times 480 equals 230400.
230400 divided by 30000 W ...
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Diy development board troubleshoot
i have designed arduino compatible diy board with Atmega328p-Pu.
,i have burned the bootloader for first time and the upload blink example to board and it didn't get any error. After that when i ...
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RC servo power switch not working properly
I am troubleshooting an ESP32 PCB I designed. Every function is working properly except the RC servo (Futaba HPS-AA701) I am using is not switched off when its ground is opened by a switch.
My PCB is ...
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BLE in STM32WB does not work on a custom PCB board. How to check where the problem is?
STM32 - STM32WB55CGU6
Antenna - 2450AT18B100E
Filter - MLPF-WB-01E3
Please help me fix the problem with my custom PCB board and BLE. The antenna on the board won’t work (I don't see my device via ...
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Potential static fault on chassis of system
The image attached is to demonstrate the observed behaviour. As the robot nears the push pads to charge, it moves its actuators down to make contact and as the contact is made the internal computer ...
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Datexel DAT3024 4-Ch Digital to Analog Converter (0-10V and 0-20mA): Voltage Output Titles Not Responding
Issue:
I was attempting to perform the calibration procedure for the DAT3024 when all 4 output channels stopped responding to modbus commands to set their respective voltages. This occurred after ...
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Unloaded N-type FET has same voltage on drain and source in OFF state
I have two FETS where FET 1 has its drain connected to a voltage supply and its source connected to a common leg, and FET 2 has its drain connected to the common leg and its source connected to a ...
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87
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ADXL335 accelerometer just reads high when using breadboard [closed]
I am using an ADXL335 accelerometer connected to an Arduino Nano 5V. For some reason, the accelerometer only reads the highest possible value.
As some context, I am only working with the sensor and ...
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Why is one op-amp in my circuit messing up the other?
I am attempting to create a board that takes an input signal, outputs the buffered input signal and its inverse, and then also outputs the difference of those signals once affected by an outside ...
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HDMI ground loop from gaming PC to AVR
I have a ground loop from my HDMI from gaming PC to AVR. It's very annoying.
Aside from getting an expensive ground loop isolation transformer for 1000 W, is there any other way?
Is there an HDMI ...
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Transimpedance amplifier circuit with uniform light input gives a sine wave output
I am trying to build a transimpedance amplifier circuit on a PCB (as in the figure below).
Although I have run a SPICE simulation and got the desired results, I wanted to test it out on a breadboard ...
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Current Spike when charger plugged in?
Here is the rough set up of the system:
Relays used 1-1393277-4 (https://www.farnell.com/datasheets/2243264.pdf ).
The way the set up works is when the battery is turned on, there is a micro (not ...
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AOZ2264 not starting up
I am struggling to find a reason why the AOZ2264 won't start up. I am using a 5V regulator to power the VCC pin on the AOZ2264
Find the schematics which I am using for my PCB. Not sure if there is ...
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1
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644
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What is the proper voltage for each phase of a 3 phase system
So i was checking voltages of a 3 phase system, so i checked the voltage of each phase going into my breaker with reference to ground, but what i got is something weird
A - GND : 50 VAC
B - GND : 200 ...
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My Wien bridge oscillator doesn't work, what could the problem be?
I suspect I am making a probe connection mistake, but couldn't figure it out.
The circuit works fine in LTSpice but I don't get anything in a real experiment.
What might be the problem?
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Troubleshooting simple JFET preamplifier design
The circuit shown below (with actual measured values) simulates correctly in as much that it provides some gain.
When I have built the circuit connected it to a signal generator using a 1mVp-p zero dc ...
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DC-DC converter fault output
We have a design using 4 EM2130L02QI dc/dc converter all with very similar routing and component placement. the output gets shorted to GND and never changed . the same board that contain with another ...
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Relay system not always working
I've got a project I just put in place and I've run into troubles and it's a little above my knowledge level so I'm looking for some suggestions.
Goal: Control a 220vAC pump from 2 locations
...
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