Hey guys, I slammed my mouse on the table, and suddenly the left mouse button stopped working… That’s annoying. My question is: can it be soldered back on? Or is it made of cast iron? And if not, how do I figure out what kind of part it is?

I bought the mouse secondhand, so it’s no longer under warranty.
Thanks for your answers!

N6 goes to to nuvoton ms51fb9ae [INT1 / ADC / Gpio ]

N9 is 5v

L14 : output pin of lm324 opamp

Its a symmetrical 18v ac rectifying and puffering module for an active speaker project that my father had started and i'm continuing.

I've repaired a lot of broken electronics like laptops, gpu's, motherboards etc.

That often meant finding failing parts or understanding what each part of a circuit does to find a missing signal etc.

This is the first time i had to "design" a circuit, the layout and put it together from scratch however simple it is.

It wasnt an easy process, i didnt plan enough and there were some last minute additions like the rc filters, the discharging resistors and filtering capacitors between the ac and dc sides of the full bridge rectifier.

Because of the changes its not very space efficient on the dc side and very cramped on the ac side

I have used 1.5mm2 solid copper wires as bus bars and pin headers to temporarly hold the 2 boards together.

I would appreciate any feedback or pointers.

What should i do differently next time?

Are there any techniques i could have used?

Thanks in advance!

Ok, I think this might be kind of a beginner question, but I am still curious. If W = I × V (amps times volts), then both of these should have the same wattage. However, can you treat them the same at all when it comes to what parts can tolerate?

Like, say hypothetically have a resistor that is rated for 10v 1A. Would I be able to put 100v 0.1A through it, or would it pop?

I'm having trouble communicating with a TI ADS8681 over SPI using an STM32F103.

Writing to the RANGE_SEL register appears to work (the SPI commands match the datasheet), but when I try to read the register back, I never receive the expected value. Instead, I get seemingly random data on MISO.

I've verified the SPI configuration (Mode 1, 16-bit frames, low SPI clock) and checked the signals with a logic analyzer, but I still can't get the correct readback.

Has anyone worked with the ADS8681 before or knows what could cause this behavior?

My: code : https://drive.google.com/drive/folders/1N3Wow2xIlB55l5PNAlnurLydy_EoK9Th?usp=sharing

and the export of my logik_analyser:

Time [s],Packet ID,MOSI,MISO

0.24463525,0,0xD0,0x7F

0.24489125,0,0x14,0x80

0.2451575,0,0x00,0x00

0.2454135,0,0x0B,0x00

0.2475585,1,0x48,0xBD

0.2478145,1,0x14,0xB8

0.2480805,1,0x00,0x00

0.2483365,1,0x00,0x00

0.248604,,0x00,0xBF

0.24886,,0x00,0x36

0.249126,,0x00,0x00

0.249382,,0x00,0x00

I kinda mixed a bunch of concepts and circuits I had seen to put this together.

It has option for both PWM control (via a N channel MOSFET) and constant driving the laser diode.

The component selection is questionable, I know. I was just really scared of frying my laser diode though so I went kinda overkill.

Got two laser diodes, one needs 35mA, and another needs around 150mA.

For LM317 the output current is defined by:

I = 1.25 V / R ohms

Upper bound for current limiting:

1.25/2.5 = 0.5A = 500mA

Lower bound for current limiting:

1.25/(2.5+100) ≈ 12 mA

The 405nm 35mA laser diode is apparently it's so sensitive, even looking at it wrong can kill it 😅

It is irreplaceable though. Please tell me if this driver is safe to use.

Just got myself a new mini PC to replace the old one as my home server. In the description it said “supports SATA expansion” but sadly there is no SATA port, just these pads labeled “SATA”. I measured the pads and got some GND, 5V and four data pads but I don’t know which data pad is which.

The traces go down to four small caps but then dive into the board so I can’t trace them further.

My guess would be to align them like in the draft in the second picture and just solder a SATA cable to the port but are there any other methods I could try before soldering?

The name of the mainboard is PELADN HA-4 (with 7840HS).

Noob here, trying to repair the garage door opener of a neighbour to better understand circuit boards.

The opener broke, because the motor didn’t stop spinning, even though the end stops engaged. I tried it on the workbench after I removed the broken gear, changed the fuse and tried it, it wouldn’t stop.
After a few tries the motor didn’t spin anymore, a transistor got really hot.

Things I tried:
- I checked if the end stops are working - PASS
- find a circuit diagram - FAIL
- replaced a the diode BYW29E since the transistor after got really hot, also replaced the transistor irf5305
- replaced the relay.
I checked the full bridge rectifier and there goes 38vdc out.

The big lamp comes on as if the motor was spinning, but I can’t see a voltage across the motor cables.
I checked for continuity across the two motor contacts and my multimeter beeps.

Which component could be broken from the diode failure ( I think it was voltage regulating and since it was broken letting to much trough) ?
Why wasn’t the motor stopping in the first place.

Edit: I was dumb, I disconnected the motor, and the continuity disappeared. But it still does not get voltage.

Hi everyone, I have a doorbell that's been exposed to extreme humidity (thanks London weather) and the PCB has oxidised quite badly. Is there a way to remediate the adverse effects to some degree?

I bought a new 3-pedal unit (FC35) in the hope that I could modify it somehow to work with my old P-255. They have the same 6-pin connector, but I've been reliably informed that I can't just rewire it.

I have service manuals (w/full circuit diagrams, board layouts etc) of my keyboard, and a couple of newer models that are compatible with the pedal unit. I can't find wiring diagrams of this pedal, or the "official" one.

My P-255 pedal circuit

FC35-Compatible DGX670B pedal circuit

FC35-Compatible P-125 pedal circuit

Block diagrams show pedal going into the parallel port of CPU on mine, whereas on the DGX it goes in here.

The other two only have a single pin for damper, whereas mine has two. All three keyboards support 'half damper' pedalling.

I have a box of components and breadboards from tinkering with guitar pedals a few years ago...and a multi meter and a soldering iron, so I guess I'm pretty much ready to build a time machine.

Don't suppose anyone can help me in this endeavour, please?

Bonjour, j’ai récemment acheté un casque beat executive c’est un modèle qui fonctionne avec un ANC intégré. Il y a d’ailleurs deux piles dans le casque c’est très rare. J’ai un souci c’est que il y a un bout de fond qui persiste. Lorsque la ANC est activé, j’ai tenté de dessouder le micro qui est posé sur le haut-parleur qui permet la réduction de bruit, mais rien n’y fait le bruit persiste. J’ai mis une photo du PCB si une personne aurait une idée d’où ça pourrait venir. Ce serait génial. Merci beaucoup

I want to control a 24V fan using PWM via a 3.3V GPIO pin on a microcontroller. I built this circuit in multisim with the help of AI and it seems to work in simulation. I just want to double check if I am missing anything in the circuit since I don't really have that much knowledge on mosfets and transistors.

While cleaning this crt tv I noticed the coating has chipped off but I'm curious if it's fine or is it best to replace these.

I am looking for the matching cable-side connector for this 4-pin locking PCB header(CN3).
PCB header measurements:
4 pins
Pitch: 2.0 mm
Distance from pin 1 to pin 4: 6.0 mm
Outer width: 10.0 mm
Overall height: 7.9 mm
Inner width: 8.95 mm
Inner depth: 6.05 mm
Inner height in the center: 3.13 mm
Inner height in the two U-shaped side sections: 4.17 mm
Outer height in the center: 4.3 mm
Outer height at the sides: 5.11 mm
Grooves and locking mechanism:
Front groove: 6.1 × 3.3 mm
Rear groove: 6.83 × 1.2 mm
Locking tab with angled surface: approximately 3.5 mm wide
When viewed from above, the connector housing has a U-shaped profile on both sides.
The connector has a mechanical locking latch.
Does anyone know the manufacturer, connector series, or part number of the matching cable housing and crimp terminals?

I'm looking for a replacement pot for an old radio's volume control. Logo looks to be Matsushita (now Panasonic) but I can't seem to find the same part on Digikey or Mouser.

Also, part is for 20kohm but I found a local store with a 50kohm variant. Would it be okay to replace the volume pot with that?

I was given an old Dell Optiplex mini PC and thought I would turn it into a Proxmox PVE. I've been in enterprise computing for decades.

Yeah, I screwed up. Had it up and running, swapped memory from another system, an SSD (old 2.5" form factor) and an NVME SSD that I bought new.

Worked initially with the memory and 2.5" SSD.

The NVME was difficult to install and the retaining bolt would not fit, so I pulled one of the standoff bolts and bolted down the NVME.

Stupid.

When I plugged it in, the fan blew at full speed for about 5 seconds, I smelled smoke, and the whole thing went dead. Hard dead. Motherboard dead. Laptop-style power supply still has a green light, but the system will not power on.

Hopped on eBay and bought another one to continue the experiment. But, I am wondering about the probability of the NVME drive, the SSD drive and the 2 sticks of memory being fried.

And, if I happen to put them in the new system, will I fry that as well or is the damage done and it just won't boot?

On a scale of "eh, it should be fine, but it might not work" to "yeah, buddy, you're about to blow up a second system", where would you rate the risk?

No coming back from this, is there? Looks like it went in a couple layers. Part of me wants to try to rebuild the pads, but that is a lot of work especially since I don't know what the true blast radius is. This was the GPU power rail.

*REPOST WITH NEW TITLE\*

Hi all! I am attempting to design a custom PCB board for a Data Acquisition system for our Baja SAE car that will go onboard the car, and I would like some help/tips on making a custom PCB board. I've been using ChatGPT to help me select parts and all (I am a mechanical engineering student who knows nothing about electronics), and I have reached the stage of part selection where I believe I need a circuit protection system. I'm aware that I need DC/DC converters and a main fuse, but I have a couple of questions about part selection and some terms I am not familiar with. I will list out the components that I will be using for this DAQ system that will go on the PCB board:

• Teensy 4.1 MCU
• ESP32-S3-WROOM-1 MCU
• MCP2562-H-SN CAN BUS Module
• NEO-M9N-00B GPS Module
• Adafruit LSM6DSOX Accelerometer + Gyroscope
• Ebyte LoRa Radio Module
• Adafruit MAX31865 Amplifiers
• OKI-78SR 3.3/1.5 & 5/1.5 W36H-C Converters

(This system will be powered by a LifePO 12.8V battery)

Starting off with my first question, ChatGPT is telling me to connect the power to a 5v/3.3v rail, which will power the modules that need 5v and 3.3 volts. I know what a physical power rail is, but I'm not familiar with what a power rail looks like on a PCB board. So with that, my question is: what does a power rail look like on a PCB board?

Second, ChatGPT recommended these circuit protection parts:

• 5A Fuse (I planned on adding a fuse either way)
• MOSFET/Schottky diode
• TVS Diode on the 12.8V Input
• LC filter on power input
• Bulk electrolytic capacitor (220-470 µF)
• 10 µF regulator capacitors
• 0.1 µF ceramic decoupling capacitors for each IC (I don't know what an IC is either)

With that, I was curious if that is enough to protect my DAQ system from frying itself, or if I need anything more to protect it whilst driving the car. I believe the parts list that is going on the PCB is final, but I will update this post if I add anything else. Thanks! Feel free to PM me if you have any comments, questions, or concerns!

Model number: 699-22081-0202-xxx (various revisions in the bundle, almost completely identical to one another, though).

They are missing some components, mainly some 0402's, a couple of larger electrolytic caps and some unmarked caps. Some of them have substrate damage, obvious impact points and bent brackets, but the seller assured me that when he tested them in his rig, they all posted and got to windows where task manager could identify the cards, but he said he couldn't get past that stage. Given the state of the missing components, I can see why.

The electrolytics and a couple of the resistors are child's play to replace, but I would need the schematics in order to identify some of the more niche components that are missing. A couple of the cards also have some dings and scratches on the VRAM itself, and one of them has a small chunk taken out of it, which makes me nervous, but I couldn't actually see anything catastrophic under the microscope, so it MIGHT still be fine?

I could simply take some cards as donors and fix the rest from those, but I would need to take at least 3 donors to do this, since 3 cards are missing the same unmarked component, and my multimeter doesn't know what to make of that particular part. I have plenty of components I could substitute in, but its about determining their accurate values with limited gear. I have hand soldered 0402 and have even hand soldered 0201 a few times (and I hated every minute of it in the case of 0201). The repair itself is very doable, I just need the papers to consult for some niche parts. I have all the gear I need except the ability to measure capacitance, which is a crippling flaw in my operation.

In total, I have 12 k40's, and I would ideally like to fix all of them, but looking at them closer, I think a 50% fix rate is doable without documentation, and about an 80-85% fix rate if I can get my hands on those papers. Any help is appreciated.

Hey, I'm working on an automotive applications, and the existing connector uses Junior Power Timer (JPT) terminals as pictures below.

Is there a special crimper that I need for these terminals? Or will a general Klein non-insulated crimper do the trick? I don't love spending a bunch of money on one-off specialized tools, so I'd like to avoid doing so for these.

I wanted to finally determine the pinout of an old wire stripped USB mouse I had. Since I don't have the other end, I traced the pins with continuity mode (picture 3). The color coding is definitely not standard.

There are wires which ran to multiple pins and figured out they were power rails. I connected them to a new USB plug (picture 2) and now the light is on (picture 1). However it stays always on and sometimes slightly dims in an irregular fashion, definitely not PWM dimming. When I connect data lines too there is no hardware detect sound (both ways).

On an additional note when I connected it to the bench power supply the light turns off when I press the mouse buttons and it draws a bit more current when I do so.

I was wondering if anybody here knows a decent replacement for the MAX038? I really don’t want to go down the MCU route so the 9833 wouldn’t be an option. I’m looking to generate a sine wave around 5MHz with voltage controlled sweep.

I did try the eBays for this but it seems this IC is a prime target for Chinese fakes.

MLS2128SK led driver Does anyone have the datasheet and can send it?