Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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.

When asking questions on troubleshooting a circuit try to include a specific circuit and describe the steps you have taken so far to diagnose the problem. Some further information on some of the things that can be problematic with troubleshooting and repair questions can be found in Is asking how to fix a faulty circuit on topic?

314 questions
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5 answers

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 case of malfunction (preferably in Eagle)?
Andrey Pro
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6 answers

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 12 V input (from a connected lead acid battery)…
macdonaldtomw
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6 answers

Can I get help troubleshooting a simple hobby electronics circuit? Multimeter not measuring current drawn

I am following the experiment in the popular electronics book - "Make: Electronics third edition". However, when replicating one of the experiments mentioned in the book (specifically Experiment 3 "Applying pressure", the part under the subheading…
Archit K
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4 answers

How can I diagnose possible problems with my breadboards?

I am an EE professor, and in my digital lab my students had issues with breadboards this week (somewhat along the lines of this question). Components seemed to work when moved to a different area on the board, and I helped troubleshoot, so I don't…
lemontwist
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4 answers

Find short location on PCB

I am trying to find a short on my board. So far, I have used my fluke to measure the resistance to gain some clues but everywhere I measure 4 ohm, so that didn't work. I am thinking of trying to push <2V up to couple hundred mA with a power supply…
Frank
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10
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2 answers

Poor eye diagram, where to start looking?

I'm trying to debug a 100Mbit ethernet board and I'm running up against a problem I'm having trouble trying to resolve. This is the eye diagram for the transmit pair. The receive pair is very similar. It's a LAN8700 PHY, and I've got the MII…
akohlsmith
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9
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3 answers

How do i test capacitors?

I've just gotten through replacing capacitors on a trio of dead LCD screens (nothing's blown up yet, so far) - they either had one or two capacitors on their inverter circuit SLIGHTLY bloated, and not quite leaky. I ended up replacing all capacitors…
Journeyman Geek
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4 answers

How do I check a BJT transistor if it is still functional?

Is there a simple method to do a sanity check on a bipolar junction transistor whether it is still functional or defective? simulate this circuit – Schematic created using CircuitLab Say for example I have a circuit that used to function, and I…
jippie
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2 answers

Isolation transformer and scope when troubleshooting SMPS

I have a simple question, when troubleshooting a SMPS is highly adviced to use an Isolation transformer. But my question is this, if im using a scope to troubleshoot the "hot" side of my SMPS, both the SMPS AND scope AC power should come from the…
S.s.
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How to find a faulty bulb in a Christmas lights string

I have a LED Christmas lights string, which consists of two circuits of LEDs connected serially. It is working directly on 110V AC. Most LED sockets have 2 wires connected to them, some have three. There is a 110V socket on the other end of the…
haimg
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8
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3 answers

Why is SMPS controller IC failing?

I'm back to diagnosing power supply failures, in an LLC resonant SMPS based on the L6598, from a 400 V PFC supply with ostensibly 400 W output. I'm new to SMPS, and learning this all as I go, and the manufacturers don't know what they're doing,…
endolith
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2 answers

1/2 screen on 1953 Zenith TV

I have been working on a 1953 Zenith TV; I can get raster on the top half of the screen only. If I reverse the leads on the Vertical deflection coil, I get raster on the bottom half only. So far, in addition to replacing all caps. & tubes, I have…
B.Eyer
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7 answers

How do I find a short in an unpopulated 4-layer PCB?

I have a 4-layer PCB, designed in Eagle CAD 6.5. The stack-up is: Signal GND (ground) DVDD (digital power) Signal GND and DVDD are solid planes, with vias connecting them to layers 1 and 4. I have 4 PCBs. Three PCBs are bare - unpopulated, fresh…
Adam F
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2 answers

Does the circuit troubleshooting tool used in 2001 A Space Odyssey exist in the real world?

In the well known science fiction film 2001 A Space Odyssey there is a scene in which Bowman and Poole are trying to locate the fault in the AE-35 unit. If memory serves, they use a tool which allows for probing the circuit board and seeing on a…
user296683
6
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1 answer

Resistor in series with primary side of transformer failing

I was given a Trio CS 1554 Analog oscilloscope. It hasn't been turned on for at least 2 years, but probably a whole lot more. Today I plugged it in and it turned on. It was usable for approximately 30 minutes. I then noticed that the trace line…
Lance
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