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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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10 views

hellp, I accidentally arched the two positives on a switch with a light up tester, it sparked, now no power [migrated]

So i was going to replace the garbage disposal at my in laws place that has been leaking for years. Its an old house and nothing in the panel is labeled. So i flipped what i assumed to be the right ...
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0answers
47 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 ...
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1answer
47 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 ...
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2answers
38 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 ...
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1answer
29 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 ...
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1answer
54 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 ...
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0answers
40 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
43 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 ...
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1answer
109 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....
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0answers
32 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 ...
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2answers
189 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 ...
2
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2answers
282 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-...
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0answers
54 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-...
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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 ...
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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 ...
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1answer
70 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. ...
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2answers
187 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 ...
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1answer
76 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
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2answers
79 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 ...
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2answers
602 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
281 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
103 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 ...
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0answers
266 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 ...
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1answer
257 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 ...
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1answer
50 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 ...
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4answers
263 views

Troubleshooting expensive potentiometer

Tl;dr tested pot and it doesn't show any variation across center pin. Is it reasonable to conclude it is the broken part? Hey everybody, so recently a coworker and I were reassembling an expensive ...
1
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1answer
49 views

Schmitt trigger issues… lumpy outputs and wrong switching voltages

I'm trying to implement the Schmitt trigger found in "CMOS" by J. Baker. Here's what the circuit should look like: And this is how the transistors should be dimensioned to achieve switching voltages ...
0
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1answer
54 views

Why is the logic probe reducing current from the power supply?

I am troubleshooting a very basic circuit using an inexpensive logic probe to check values. Typically when I use the probe I see current output go up about 7mA, which I assume is to power the sound ...
0
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1answer
115 views

Troubleshooting Dimmer Circuit [closed]

First off I do apologize for my ignorance, I know very little on the topic so please be patient. I have one of these that are broken http://www.smartliving.com.au/z-wave-in-line-dimmer.html Its a ...
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0answers
97 views

Next step when troubleshooting a PS/2 keyboard PCB with good cable

I received a PS/2 keyboard (TypeMatrix 2020) which was known to be broken, with some hope that I may be able to fix it. I don't have a lot of experience with electronics, but I know the very basics. ...
2
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1answer
174 views

Computer won't post / Beep unless Unplugged for a few hours [closed]

I'm experiencing this issue for almost a year now. It is slowly getting worse. My motherboard is Gigabyte GA-Z77X-D3H and my PSU is Corsair CX600. The source of the problem most likely has to do with ...
3
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1answer
283 views

Troubleshooting 4066 as a button hack

I have an Arduino project which needs to simulate a human button press on a third-party board, an 883LM garage door opener controller. The other board has its own power supply which is separate from ...
2
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3answers
405 views

Troubleshooting wien bridge oscillator circuit with 741 op amp

I built the standard Wien bridge oscillator circuit using the UA741CN op amp IC, however I am not getting any oscillation. I am powering this circuit with two 9V batteries. I'm using the values R1=...
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1answer
139 views

Troubleshooting noisy FET buffer for contact mic

I'm trying to follow the schematic on this page to create a preamp/impedance matcher for a balanced piezo contact mic. I've reproduced the schematic below. I've built it on a breadboard and I'm ...
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0answers
81 views

Troubleshooting help with my continuity tester circuit

I don't know whats wrong with my circuit. I wrote my readings down in my picture attached, I have measuring 9.6V on both sides of R1 therefore the base of Q1 has 9.6V. However, 9.6 volts is also seen ...
3
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4answers
3k views

SMPS output voltage too low - what to look for?

I have an old switching power supply for HP 712/60 workstation (+5V, +3V3, +12v). It was working about ten years ago when i've last tried to boot the system, but now one of the output voltages is at ...
4
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1answer
409 views

Switching Voltage Regulator Problems

I'm new here, so forgive me if I breach any forum protocols in the asking of this question. I have designed a voltage regulator scheme for a guidance system on an aerial drone. All components ...
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0answers
90 views

RF Interference and Metal Enclosure

We have a product (optical detector), one client had an issue with false alarms due to their radios they use on site. Did some modifications, added a ferrite bead to the cable and put a driven guard ...
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2answers
570 views

Op-Amp as comparator for driving relay stops working after short time

Ok I have an Op-Amp as a comparator, Its the TCA0372... whole amp it can source, not needed just nice. and I have a relay, http://www.mouser.com/ds/2/315/jw-catalog-1075968.pdf Its driven by 12v. ...
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1answer
126 views

HC-05 BT Doesnt need vcc for power [duplicate]

I'm hooking up and old HC-05 BT module and it powers even if vcc is disconnected, (if TX is high and is key is high), is it likely i fried something and it's broken?
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1answer
86 views

Troubleshooting my Electromagnets

While the problems I am having span across several projects of mine, the common denominator is the electromagnet present in each project. I have made three electromagnets and none of them seem to be ...
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0answers
330 views

Error on Lattice Diamond: “core0 incorrect response (Write: 512 != Read:0) … Problem cause is sample clock too slow or not continuous”.

Question for persons experienced on Lattice Diamond, I'm trying to test a previously developed project on Lattice Diamond. The project initially shouldn't have any problems because it was implemented ...
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0answers
122 views

Schottky heating up

I'm having some issues with a BAT54-7-F schottky diode heating up. I've asked an initial question over on reddit. Relevant part of my schematic: The LED drivers are hooked up according to this ...
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2answers
583 views

EMG, Muscle Sensor Arduino - Troubleshooting [closed]

I've been testing the EMG sensor below: http://www.ebay.com/itm/Muscle-Sensor-EKG-EMG-Developemt-Electronics-Module-Interface-Kit-For-Arduino/351850511727?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=...
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1answer
65 views

Simple method to find open fault in three wire power cable?

I have a three wire power cable - live, neutral and ground. My multimeter shows no fault with the neutral and ground wires, but there is an open fault on the live wire. Nothing suspicious upon visual ...
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1answer
163 views

busted WS2811 LED strip by overpowering, totally useless now?

Powered a 5V WS2811 LED strip with 12V by accident. It turned on for a split second, it fried a microcontroller, I noticed the smell and turned everything off as fast as I could. When i tried ...
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3answers
494 views

What would cause a 120 VAC universal motor to run slower in reverse?

I got a bargain on a few small universal motor that run on 120VAC and I'm trying to reverse the direction. I don't have a lot of experience with these types of motors but I do know they run on AC or ...
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5answers
6k views

How to create measurement points on a PCB for diagnostics?

What is the best way to implement a point on a PCB, where a voltage (e. g. output of a regulator) could be measured with multimeter for the purpose of verification of the assembly or diagnostics in ...
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3answers
90 views

FlipFlop outputs half voltage SN74HC74D

I first did a simulation of a simple circuit with the IC SN74HC74D and it outputs 5V, please see attached image. I made a circuit and ordered a PCB. When soldered it only outputs 2.5V(Pin ~Q_2). I ...