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.
361 questions
1
vote
1
answer
55
views
How can I thoroughly test a circuit that requires debouncing of several components?
I recently asked for help on a circuit using a D flip flop that lets me turn a relay on and off with a momentary push button switch. That circuit uses both a momentary push button switch and a relay ...
- 151
-2
votes
0
answers
43
views
Sage barista express coffee machine not turning on, how to troubleshoot? [closed]
My Sage Barista Express coffee machine is not turning on. When connecting to mains, a relay click is heard, but upon clicking the power button in the front panel, there is no response.
The problem ...
- 109
3
votes
1
answer
112
views
How to measure where culprit is, in a Commodore 128D (plastic model) PSU?
I do have a problem with my C128D PSU, and with some help from others I think I may have identified that it must be on the primary side (230V) of things. It seems not to provide any voltage for the <...
- 143
3
votes
1
answer
81
views
Stepper motor stutters when connected to a TB6612 stepper motor driver and a Raspberry Pi
I've wired a stepper motor to a TB6612 stepper motor driver which is in turn connected to a Raspberry Pi. The wiring is as follows.
VM ---> +12V power supply (the adapter used for this can supply ...
- 65
-1
votes
1
answer
54
views
What could be the issue of burning of these capacitors asus gtx10XX series
I was using my Asus GTX 1060, normally until suddenly it made the PC shut, my motherboard may have had a protective layer that didn't allow my PC to turn on, I took my GPU to my friend to test it ...
2
votes
1
answer
162
views
Short circuit fault finding by Kelvin 4 wire method
In several YouTube videos on repairing notebooks or smartphones I have seen that the 4-wire Kelvin method is used to find the location of a short circuit in an electronic board, in practice, with the ...
1
vote
1
answer
65
views
SIM card not being detected on my NRF9160 custom board
I´ve designed a board that uses the NRF9160 SOC as its main controller and modem for LTE, right now everything works besides the SIM card. When I try to read the status from it the response I get ...
- 175
1
vote
3
answers
64
views
Identifying blown-up SMD component based on surrounding chips and found photos of similar devices
I have a device that has a blown up component, and I would like to try and replace it (as well as repairing damaged traces and cleaning up some corrosion) to see if the device still functions.
This is ...
- 11
0
votes
1
answer
57
views
How to suppress voltage sags in an AC circuit
I'm working on a 24VAC circuit where I'm encountering brief voltage sags (about 4VAC for 0.018 seconds) that are causing a relay to open and power off a larger machince. What components or devices can ...
1
vote
1
answer
56
views
Problem with an Arduino DC motor controllable circuit
I am a material science student currently working on a project to build a simple circuit for controlling the speed of a DC motor. My goal is to avoid using motor driver modules by utilizing a MOSFET, ...
- 11
0
votes
0
answers
53
views
MCP73871 and TPS61090 Troubleshooting
I apologize in advance if I violate any forum conventions here. If that happens I will adapt postings accordingly moving forward.
Context:
I have been working on a PCB design that incorporates the ...
1
vote
1
answer
67
views
TL431-based battery discharger
I have built the following circuit on a breadboard, using a TI TL431BI (datasheet) and four 80 Ω resistors in series for the load (R3). Its eventual purpose is to slowly discharge a 4S LiIon battery ...
- 183
1
vote
0
answers
66
views
MOSFET Power Control Problem: DFPlayer Circuit Not Working on PCB
I built a circuit that plays MP3 files and is controlled by an Arduino. I assembled the circuit on a breadboard, and it worked, but when I fabricated a PCB, the circuit failed. The problem is that the ...
- 113
0
votes
2
answers
70
views
Testing hook-up wires for inductance
Say a hypothetical question. A seller I'm going to has dubious merchandise & their hook-up wires, in particular, are NOT made out of typical high purity copper, like ordinary hook-up wires. One ...
- 409
0
votes
0
answers
42
views
Load cycler keeps stalling at same voltage
Hello I am building a load cycler using an arduino with this code:
...
- 27
1
vote
0
answers
58
views
Replaced MOSFET in BLDC driver keeps blowing [closed]
I have a motor and controller which, after a catastrophic fault destroyed one of the phase coils and the high and low side MOSFETs for the affected phase, I've repaired by rewinding the coil and ...
0
votes
1
answer
72
views
Power supply gives at most 20 millivolts
I have a power supply KIKUSUI MODEL PAB 250-0.25A (photo below).
The voltage source used to work correctly, but my roommates have used it for a while and now ...
- 1,187
0
votes
2
answers
112
views
Issues with Audio Amplifier Circuit - No Output Signal with Capacitor, noise
I'm having trouble with an audio amplifier circuit that I designed, and I hope someone can help me figure out what's wrong.
Here's the schematic of my circuit:
Rsig is a variable resistor
The circuit ...
- 9
3
votes
2
answers
369
views
Stepper Motor: Understanding why missed steps are multiples of 4
I’m trying to quantify the resolution of a stepper motor. Meaning, if I say travel to 500 steps, I want to define a window in which the stepper actually travels (say 495–505 steps). I realize this ...
- 31
1
vote
1
answer
51
views
Interpreting RAM diagnostic results (E-mu Emax 2 digital sampling keyboard)
I have a broken E-mu Emax 2 digital sampling keyboard (1989). I ran the unit's internal diagnostic but need help interpreting the results, which indicate a faulty DRAM chip (KM44C256BP-8, of which ...
- 11
0
votes
3
answers
107
views
Simple transistor switch does not work
I have a simple switch system based on an NPN transistor (it is supposed to be part of a larger project) which unfortunately does not work and I don't know why. Could someone take a look at what's ...
0
votes
1
answer
95
views
Troubleshooting an RF driver for acousto-optic deflectors [closed]
I inherited an old acousto-optic deflector scanner but the catch is that one axis isn't working, and I want to troubleshoot why.
These acousto-optics deflectors are powered by an RF driver and that's ...
- 65
1
vote
1
answer
104
views
SWD scan failing for STM32H747 using a BlackMagicProbev2.3
I'm trying to debug an Arduino R1 Giga WiFi board with a STM32H747XIH6 mcu, which is a dual-core ARM Cortex-M4 and Cortex-M7 chip, using a Black Magic Probe v2.3 (BMP) from 1bitSquared. I've managed ...
0
votes
0
answers
57
views
Troubleshooting power issue in LilyGo T4-S3 ESP32
I put a custom expansion board onto the nice T4-S3 devices' 2x15 header. But displaced by 1 pin (2 pins off) and shorted something out. Need help on how to troubleshoot and id the destroyed components....
3
votes
5
answers
2k
views
Resistor's markings don't match readings
I'm using a component tester to measure a resistor which I have removed from a circuit. The tester gives a reading of around 0.46 - 0.50 Ω. I have 7 other identical resistors (in circuit) and they all ...
- 229
0
votes
1
answer
44
views
Locating the temp sensor on motor controller
I am helping my neighbor with fixing his out of warranty EV UTV. I have narrowed it down to a faulty temp sensor.
-Controller: Curtis 1234SE 72vdc 3Ph VFD.
Fault code:15.
What would a label next to it ...
- 1
0
votes
1
answer
95
views
LEDs not working after switching from Red to White [closed]
I replaced the red SMD LEDs from my car's center console control unit (Audi A4 B8 2013). First the LEDs lit up and everything was fine. After a few seconds they all shut down and just flicker (barely ...
- 3
3
votes
3
answers
1k
views
Beginner: Solder won’t flow onto thermostat tabs
I’m trying to repair my espresso maker with a new thermostat but am unable to get the solder to flow. I’m a beginner but have had some experience soldering my own guitar pedals using stripboards in ...
- 31
0
votes
0
answers
61
views
Troubleshooting a Low Voltage Cutoff (LVC) Circuit for Overdraining Prevention
I am attempting to design a Low Voltage Cutoff (LVC) circuit to safeguard against overdraining my 12V rechargeable battery. The objective is to halt circuit power once the battery voltage drops below ...
0
votes
0
answers
218
views
Troubleshooting Sako Solar Inverter and Osaka Battery Charging Issue
I have a solar power system comprising a Sako inverter (3.5-5.5 kW) and two Osaka P-180 S batteries with 21 plates per cell. Despite receiving input from the solar panels, the inverter does not ...
2
votes
1
answer
99
views
Why do my boards shut off when I connect an RJ45 cable to a switch but not a router?
I made a custom single board computer based on the Allwinner V3s. This system on chip has an integrated PHY.
All components seems to work except I noticed that when I plug the ethernet cable to a ...
- 305
0
votes
1
answer
215
views
How do I troubleshoot the ESP32 USB JTAG/UART interface on a new PCB design?
Question
How do I troubleshoot the ESP32 USB JTAG/UART interface on a new PCB design?
Background
My son is working on a project to track satellites and this is the first time that we have worked with ...
- 2,200
3
votes
1
answer
444
views
Simple comparator circuit w/ LM311 doesn't work
I'm implementing the comparator circuit below, with the LM311P IC.
I changed V_in's voltage from 0 to 9, making it above and below the 10/2 = 5V threshold at the V+ input. I was expecting that ...
- 1,187
0
votes
2
answers
84
views
0 V across motor capacitor terminals, but resistance is 20 Ω. Is the capacitor dead?
It is a 36 μF, 440 VAC, 50 Hz rated motor running capacitor, used in a single-phase motor. AC source is 240 V, 50 Hz.
The motor has stopping working. I want to know whether it is due to a faulty ...
- 31
0
votes
1
answer
117
views
How to find out whether capacitor is the fault for failed single phase motor?
Single phased motor rated for 220V, 50Hz isn't working. I want to know whether is it just due to a failed capacitor or is the motor itself is damaged. The capacitor looks clean from the outside; no ...
- 31
1
vote
1
answer
61
views
Will this electric guitar wiring scheme be noisy?
I want to wire my guitar using two SPDT switches for my pickup selector. This is so I can have four sounds: lower, upper, both in parallel, both in series. I'm concerned that when it's set to use ...
- 13
3
votes
4
answers
198
views
LM1085IT-5.0 voltage regulator outputting 12 V instead of 5 V with 12 V input
I am working on a PCB board that incorporates three LM1085IT voltage regulators, all connected to a common 12 V input source. The intended configuration is to obtain a regulated 5 V output from each ...
1
vote
1
answer
126
views
Need help in finding short circuit
I designed a basic power amplifier powered by +12V/-12V. During the breadboard testing phase, the bench power supply indicated a stable voltage of +12V/-12V and a current draw of 150mA. After ...
- 105
3
votes
3
answers
1k
views
From an OEM side, how would someone be able to perform root cause analysis on application design?
Apologies for my ignorance on the subject but I am still relatively new in my career. This also might be a vague question as well. The only troubleshooting I've done on the silicon level was a dye-and-...
user319168
0
votes
0
answers
91
views
TI synchronous buck converter went up in smoke, where do i start?
I’m using a TPSM63606RDLR power module device. Everything looked perfect for multiple days, but yesterday it started smoking. I did move the PCB and there are some LED strips connected externally to ...
- 1
0
votes
0
answers
281
views
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) ...
- 149
0
votes
0
answers
80
views
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 ...
1
vote
1
answer
123
views
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 ...
- 29
0
votes
0
answers
106
views
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 ...
- 849
1
vote
1
answer
385
views
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 ...
- 409
0
votes
2
answers
284
views
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 ...
0
votes
1
answer
833
views
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....
- 125
1
vote
1
answer
88
views
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,...
- 111
0
votes
2
answers
183
views
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....
2
votes
2
answers
64
views
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 ...
- 21