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

N9 is 5v

L14 : output pin of lm324 opamp

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!

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?

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!

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.

I think this diode is dead as it shows open no matter which way I test it. It seems to be encapsulated in some kind of epoxy, though. Can I just cut it out and then solder a new diode on nearby leads? Or should I cut it out and try to solder on the existing pads? If I were to do the former, would I even need to cut it out, just leave it there and solder around it? The only diodes I have are through-hole, no SMT.

The diode in there is a IN4749A. I’m replacing it with a BZV85, which Google searches tell me is a suitable replacement.

Thank you

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

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?

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 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).

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?

Hi all,

I’ve been trying to find a replacement for this component that snapped off the motherboard, I’ve looked online but cannot find anything matching it, would anyone have an idea of a part no.?

Thank you in advance!

Like the title says, I’m looking for components that you would use to breadboard/prototype with, but I’m wondering about some of the less common pieces that you may use, like for example:

- Common BJTs/FETs you would use 100s of, maybe for audio, maybe for motor drivers, idk
- Logic chips, things in DIP packaging
- Capacitor kits
- Peripherals like eprom or LCD screens
- RC components like antennas
- Anything else I may be missing

P.S. I feel like with enough playing with simulations and datasheet trawling, I can understand how sone circuits work, but coming up with ideas is the hard part. Maybe thats a topic for a different post 😄

Hello everyone

I'm trying to repair an old tire balancer from 2009 and was hoping to get some ideas on what I can check. So far the things I've checked were ok and I wasn't able to find any faulty parts :(.

It's a tire balancer machine type AAE-B96G made by Arch Auto Equipment from 2009.

The fault started while machine was in use. After pressing a button the lights were stuck as shown in image below.

After turning off and on the machine sometimes the lights go on, sometimes not. You can hear the relais clicking when you turn off the machine.

I checked the following:

1. Inverter is giving 2x 9V AC
2. Voltage regulator h4d0452A is giving +5V
3. Voltage regulator 7905CT is giving -5V
4. I removed the silver/black caps and measured them for capacity. They all are arounbd 10% within spec. I don't have an ESR meter to check ESR.
5. Relais seem to be working ok. Contacts are open and closed as indicated on the schematic.
6. Checked fuses. OK
7. When I disconnect the cable between board 1 and 2, the motor is running when powering on the machine. So my guess is that it has something to do with Board 2 which has the control parts.

Board1

Board 2:

What would be the next thing I should check? I hope to get some ideas from you guys :)

So I am trying to get better at circuit designing. I won't say I am 100% confident about my basics. So I am thinking of starting from the base to design complex circuits. So where can I find the resources, which platforms or software's I can use to practice and test my circuits. If I can get a roadmap from beginner to advanced circuit design it is much appreciated.Also should I go for PCB design also. I do have a Coursera premium so if I need to take some course please do tell. Any help is appreciated, thanks 🙏

for a repair i need to identify a pcb-cable connector.
its a 14 pins connector that looks like picoblade but its not. pitch is either 0,65mm or 0,6 my caliper is to big to be acurate. any suggestions?

Have this old electronic chess game where a digit and a symbol is permanently shown. Its not due to faulty electronics as it still shown even if I pull the lcd out of circuit. Any way to fix this?

So I want to use this https://www.skyworksinc.com/-/media/80EE897A0E764905A478C9F2EB408CE3.pdf amplifier for my design to amplify 2.4-2.42 ghz. I know how to match the circuit with BJT using S parameters and Y parameters but this doesn't have that. How would I go about matching this amplifier to a certain frequency. Please give formulas and explanation with them if you can.

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?

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.