Skip to main content

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.

Filter by
Sorted by
Tagged with
1 vote
0 answers
36 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 ...
R.. GitHub STOP HELPING ICE's user avatar
0 votes
1 answer
70 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 ...
ludicrous's user avatar
  • 1,163
0 votes
2 answers
78 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 ...
CHIEN LE's user avatar
3 votes
2 answers
319 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 ...
FaulknerW's user avatar
1 vote
1 answer
41 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 ...
Eric Svoboda's user avatar
0 votes
3 answers
103 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 ...
user3788160's user avatar
0 votes
1 answer
67 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 ...
Omnistic's user avatar
1 vote
1 answer
60 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 ...
Antonio Bassi's user avatar
0 votes
0 answers
24 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....
Diego Alacerna's user avatar
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 ...
Alan A's user avatar
  • 209
0 votes
1 answer
36 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 ...
ClintG's user avatar
  • 1
0 votes
1 answer
92 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 ...
TJCDE's user avatar
  • 3
3 votes
3 answers
974 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 ...
tylorreimer's user avatar
0 votes
0 answers
55 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 ...
Karampistis Dimitrios's user avatar
0 votes
0 answers
82 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 ...
anwar ali's user avatar
2 votes
1 answer
88 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 ...
Varech's user avatar
  • 305
0 votes
1 answer
114 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 ...
KJ7LNW's user avatar
  • 2,012
1 vote
1 answer
206 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 ...
ludicrous's user avatar
  • 1,163
0 votes
2 answers
74 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 ...
Cinverse's user avatar
0 votes
1 answer
79 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 ...
Cinverse's user avatar
1 vote
1 answer
57 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 ...
neenscrame's user avatar
3 votes
4 answers
186 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 ...
Karampistis Dimitrios's user avatar
1 vote
1 answer
107 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 ...
T1P0Z's user avatar
  • 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-...
user avatar
0 votes
0 answers
78 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 ...
Bibber's user avatar
  • 1
0 votes
0 answers
148 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) ...
tom's user avatar
  • 149
0 votes
0 answers
70 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 ...
Magemathician's user avatar
1 vote
1 answer
89 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 ...
mm3psych0sis's user avatar
0 votes
0 answers
94 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 ...
SystemTheory's user avatar
1 vote
1 answer
304 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 ...
Tempus Nomen's user avatar
0 votes
2 answers
147 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 ...
flower.fish's user avatar
0 votes
1 answer
547 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....
Maxthecat's user avatar
  • 125
1 vote
1 answer
83 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,...
lp1756's user avatar
  • 111
0 votes
2 answers
131 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....
OnlyServeSwill's user avatar
2 votes
2 answers
61 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 ...
Lucas-WT23's user avatar
0 votes
1 answer
259 views

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 ...
Jochen K's user avatar
0 votes
0 answers
153 views

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. ...
TooTea's user avatar
  • 510
0 votes
1 answer
50 views

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 ...
Tesla's Curiosity's user avatar
0 votes
1 answer
100 views

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 ...
Lukas's user avatar
  • 3
3 votes
1 answer
532 views

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 ...
Joshua S.'s user avatar
1 vote
2 answers
261 views

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 ...
mike_s's user avatar
  • 21
5 votes
1 answer
329 views

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 ...
Lil Mami Chula's user avatar
0 votes
0 answers
51 views

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 ...
AyubowanPro's user avatar
0 votes
0 answers
105 views

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 ...
Ivy Growing's user avatar
0 votes
1 answer
122 views

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 ...
Lil Mami Chula's user avatar
0 votes
2 answers
492 views

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 ...
import_hill's user avatar
5 votes
1 answer
162 views

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 ...
Lars Petersson's user avatar
0 votes
1 answer
60 views

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 ...
D.Mendez's user avatar
0 votes
0 answers
482 views

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 ...
Austin Strand's user avatar
0 votes
2 answers
189 views

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 ...
sidyll's user avatar
  • 279

1
2 3 4 5
7