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.

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1answer
79 views

H-Bridge shoot through at high voltage problem - Don't know the cause

I have this H-bridge circuit The circuit is for driving a 180VDC motor, it is built to taking in the High Bus voltage from 169VDC to 340VDC. it works with no problem up to 310VDC. However, at 340VDC, ...
2
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2answers
142 views

What is causing a white scale buildup at copper pin connection on LED light sticks and how can they be cleaned?

Can someone explain what is causing this white scale to appear on the copper pins and on the block of this LED light connection? The seal at the connection is supposed to be watertight. On occasion, ...
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0answers
72 views

How to rule out that you have a faulty power supply?

Just for context: I'm trying to code an ESP8266-ESP01 through an arduino, but I'm failing and my primary suspect, as per other forum issues I read, is that the power supply is the fault. I've tried ...
0
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1answer
42 views

Custom STM8L dev board not working

I designed a dev board for the STM8L151F2, and even using an external programmer and external power the STM8 has only been able to be programmed twice. Here's the schematic, everything done in eagle. ...
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0answers
26 views

Pin assignments do not appear to be assigning in bdf - Quartus 17.1

Following the pin assignment diagram in the device manual for my Max 10 DE10-Lite, I assigned all the correct pins to their associated inputs and outputs as seen below: However, when I go back to my ...
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2answers
150 views

Low pass filter not working properly

This is the pass band that I'm using to filter some EMG signals through electrodes. When I test it with multisim it works really well as you can see, but when I test it with real equipment (...
0
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1answer
121 views

Need help on troubleshooting PCB circuit

I recently got a freelancer to design a push-button latching circuit that powers a 12VDC motor from a 1S1P Li-Po cell. I have soldered all the components but the board does not seem to work properly. ...
0
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1answer
59 views

Need help troubleshooting after short-circuit, with heaters and thermocouples

There was a short circuit in one of the furnace that I designed. Description of the furnace and its components: The furnace is a copper tube, with 1/2 inch thickness, and 10 equally spaced 1/4 inch ...
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1answer
40 views

DC Power supply stopped working properly

When I needed to set a maximum current I shorted the outputs and set the desired value with the current knobs. Now it doesn't work for some reason. Here's a short video. Any idea what's going on?
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0answers
45 views

DC power ok light is “off”

I've run into a power supply I believed was faulty, but turned out to be working properly. Operator complained he's lost control voltage. When I got there everything was working as it should, except ...
0
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2answers
97 views

Reading data from Pressure Sensor

I am having trouble reading data from a pressure sensor using MATLAB. The pressure sensor is connected to an NI 9219 Analog Input Device. Firstly, i tested the device to make sure it is working using ...
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2answers
76 views

Need help with circuit troubleshooting, Red LED constantly lights up

I have problem with the following circuit below. The Red LED is constantly lighting up, but I cannot figure out why. For the LM339, the voltage readings I get are as below. Shouldnt Out1, Out3 and ...
2
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0answers
67 views

Need help troubleshooting Teensy 3.6 SPI to DAC8568

running out of things to check with this problem I'm having. I designed a board around the Teensy 3.6 microprocessor, and I wanted to connect a DAC8568 chip to it for some analog outputs. It works ...
0
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1answer
55 views

DC voltmeter gives unknown reading when powered

I just bought a DC 3 wired voltmeter and it was working perfectly. Here is it image: I used the yellow wire for measuring the voltages. But for some reason, I desoldered the wires and soldered pin ...
1
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2answers
88 views

Confirm transformer fault vs markings / spec

I'm trying to troubleshoot a German ceramics kiln controller from about 1989. There is a 100ma glass fuse in front of this PCB transformer that blows after a second or two when power is applied. ...
1
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2answers
84 views

Chua's circuit producing unexpected waves?

I have built the Chua's circuit in the following diagram: I then hook it to a soundcard oscilloscope. It produces the following wave: Such waves doesn't change no matter how many times I repeated ...
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0answers
55 views

Chua's circuit's pattern not fully shown

I have made a Chua's circuit, and hooked a soundcard oscilloscope to it, to measure the voltage across C1 and C2. Circuit diagram: Source:Kennedy 92(pdf). Software used: soundcard scope. The ...
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0answers
36 views

USB detected, no communication

I had a device come with no USB cable. Since it used a proprietary USB connector on the device side, I decided to solder a male USB A cable directly on the motherboard pins. The USB device is ...
0
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1answer
85 views

Strategies for troubleshooting buck converter

I'm trying to troubleshoot a tps65261rhbr triple synchronous buck converter from 12V producing 1.8V, 3.3V and 5V. The 3.3V and 1.8V are stable and well-functioning but the 5V is not. An oscilloscope ...
0
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1answer
113 views

Why the DC voltmeter does not read zero when it measures an AC signal?(Chua's circuit) [duplicate]

I have made a Chua's circuit that is nearly the same as the one in Kennedy 92(pdf). I don't have an oscilloscope yet, so I connect a DC voltmeter at the place where probes of oscilloscopes should be ...
1
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2answers
107 views

Help With Buffer Amplifier/Filter Type Circuit

I’m having trouble with a circuit I designed and I would be greatly appreciative if I can get some help here. The circuit I designed is a buffer amplifier type design intended to take two channels of ...
-1
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1answer
515 views

How to check (6 pin) PCI-E power rail on a pc powersupply?

Could anyone tell me if and how i might verify whether or not a PCI-Express 6 pin power lead on a PC is outputting correct voltage(s) ? A while back, I decided to try to refurbish a graphics card ...
2
votes
1answer
73 views

Current monitor circuit not working

For part of a project, I am needing to monitor the current draw of 4 low power loads simultaneously. I like experimenting with circuits and I found one online in a TI application note (AN-31 page 35) ...
0
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0answers
344 views

Wemos D1 mini doesn't boot with common ground with PZEM-004t

I'm experimenting with Wemos D1 mini and PZEM-004t to monitor my home electricity, but I'm having a strange issue. I'm trying to supply PZEM-004t independently from a Wemos with a dedicated AC/DC 5V/0....
0
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0answers
62 views

HJS-480-0-24 Power Supply begins smelling like burning plastic after 30 seconds of running

I recently purchased a HJS-480-0-24 power supply off Banggood and I tested it out by running a 150 watt heater. After 30 seconds the power supply began to smell like burning plastic, so I immediately ...
0
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0answers
92 views

Tesla Coil / Slayer Exciter won't work

I need some help with troubleshooting a slayer exciter circuit or coils. I was following this youtube tutorial and doublechecked all the connections. The power supply I use is 12V 1.5A. My secondary ...
0
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1answer
117 views

tube amp - high power supply voltage ?! troubleshooting

So I started working with troubleshooting a channel imbalance on the schematic attached, 12ax7 + 6L6GC push pull. But the problem seems to be a bit different... My voltages seem to be a bit hot!! (a ...
0
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2answers
405 views

Constant flickering of TFT Display

We have an issue with our TFT display. The display constantly flickers while displaying. What are common causes for flickering in this type of display? How can we resolve this issue? It's a 3.5 inch ...
1
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1answer
91 views

Power button behaving as OFF-(ON) momentary switch rather than latching- Troubleshooting

I have a device which doesn't turn on normally when you press the power button like it did before. You have to keep holding it down for it to remain on. As soon as you let go, it turns back off. In ...
0
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1answer
77 views

Turnigy servo motor needs push to start

I currently have an inspection robot deployed in a remote part of Africa that has a failing Turnigy TGY-6114MD servo. The issue started happening during normal operation and was working fine ...
0
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0answers
91 views

EMG signal from MyoWare board - sudden increase in output voltage

I am using the MyoWare muscle sensor from Advancer Technologies (this one) to obtain EMG signals from my forearm. I want to use it in a project where I will be checking if the muscle is flexed or not. ...
2
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2answers
48 views

LMR33630A, my built circuit doesn't match the expected output

Using TI's "power designer", I've taken their 33630A and designed it for a 5v output. My actual circuit has a slightly different value for the divider to raise the voltage up to about 5.2v, otherwise ...
0
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1answer
112 views

Avoid fire on a battery-powered device [closed]

I was trying to repair a battery-powered electric razor when I suspect there was a short-circuit. The device started heating and it began smoking a bit so I took it and put it in a bowl full of water....
0
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0answers
36 views

What are some techniques to troubleshoot a second order sigma delta loop?

I have designed a slightly modified second order (3-bit) multi-bit incremental sigma delta modulator (IDSM) in simulink (system level). The SNR that I get is 45dB, which is not as expected. But ...
0
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2answers
393 views

Strange behavior of the DALI controlled luminaires

I faced a strange behavior of a DALI controlled LED luminaires circuit. I have 48 LED luimianires with a MeanWell ELG150-C700-DA drivers connaected according to the scheme below: I commissioned the ...
4
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2answers
474 views

32.768 kHz Crystal Troubleshooting

I'm at my wit's end trying to get a 32.768 kHz tuning fork crystal to work and I don't know what I'm doing wrong. First, some background: I'm using a 16MHz crystal in conjunction with an Atmega 328P-...
0
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0answers
69 views

can't figure out why my micronucleus/V-USB setup doesn't work

I built a small attiny85-based board using vusb and essentially the schematic of the discontinued Sparkfun "AVR Stick" (at least on the usb/uC side; see https://www.sparkfun.com/datasheets/Widgets/AVR-...
5
votes
4answers
5k views

Is a capacitor bad when it looks like this?

Hello I am new to the electronics field. I am looking inside of one of my synthesizers and I see some capacitors (I think they are Mylar, correct me if I'm wrong) that look like this. I know it is a ...
2
votes
3answers
1k views

Troubleshoot a backplane

I have built a simple bus backplane from stripboard and 40-pin female headers for a computer project I am working on. When I tested the backplane to make sure that it functioned, I found that it's ...
0
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1answer
103 views

Identifying damaged, burnt out, or missing components [closed]

Is it possible to deduce the identity of damaged, burnt out, or otherwise missing components (or suitable substitutes)? For example, below is the PCB of a 2 speed electric razor I've disassembled. ...
1
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2answers
305 views

MCU overheating

INTRODUCTION I've designed a custom board featuring a SAME54N20 MCU. This is the third board I assembled but I still haven't got any to work: I didn't get the first board to connect to my PC. My ...
0
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1answer
83 views

Best way to locate a 4k stray resistance between 2 bus lines in a PCB?

I have a faulty PCB which is showing an unexpectedly low resistance between certain pairs of bus address lines. I'm measuring a little over 4k ohms between these bus lines, but according to the ...
19
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6answers
3k views

Why would a buck converter IC fail and blow up?

I have a deployed design in which we are experiencing a high (~4%) failure rate in the 12V to 5V step-down buck converter portion of the PCB. The buck converter's role in the circuit is to step down ...
1
vote
2answers
116 views

AL5802 LED-Driver works on the breadbord, but not on its (seemingly functionally identical) PCB

TL;DR: I'm working on a project that incorporates (besides other things) two AL5802 linear LED-drivers in parallel. Unfortunately, I felt balsy and had my complete PCB made in China before testing the ...
0
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2answers
876 views

Why is the MCP601 better suited than the LM833 for single supply applications?

Still not answered, please need some help. If you guys don't know the answer don't be afraid to admit it, but I want to generate discussion around potential solutions/calculations and not semantics ...
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1answer
375 views

Tesla Coil Troubleshooting Help! [closed]

A couple weeks ago I decided to build a tesla coil and after a decent amount of research and building time the coil could only light up a light bulb. I have tried many things to fix it but all to no ...
0
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1answer
123 views

Overvoltage at input causes small jump at IC input pins

I have a PCB with voltage regulator (5V), op-amps, 2 multiplexers, 1 counter, several pots, caps, and resistors. I supply 9V. The voltage regulator converts it to 5V. Without connecting any ...
0
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0answers
655 views

How to troubleshoot a switched-mode power supply?

I am trying to repair a switched-mode power supply, but as of now I have no success. The problem can be described as following: The supply does not output any voltage whatsoever. The fuse never ...
4
votes
1answer
433 views

Observing ethernet auto-negotiation packets using oscilloscope

In an answer to one of my previous posts seen here: Verifying 802.3 auto negotiation, @Zac67 mentions that by using an oscilloscope I could observe normal and fast link pulses that are sent in order ...
0
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1answer
76 views

Troubleshooting an op-amp for amplifying a low voltage AC input

I am trying to amplify a low voltage AC input with a gain close to 5. It has a 0 DC offset and about 300 mV of AC amplitude, at 250 kHz. This is my first venture into electrical engineering and I’m ...