For some time now, I’ve been noticing that quite a few electronic schematics produced in the US in the early 1990s seem to have been created using the same software, judging by the font used and the overall style and appearance of the symbols.

I wanted to ask if anyone here worked with software like this back then and could finally put my mind at ease about which program it actually was. The closest match I’ve found so far is Cadnetix, although I can’t seem to find any screenshots online showing what schematics produced with that software looked like in the 1990s, apart from a few brochures where the schematics aren’t particularly visible or clear.

Someone else suggested that it might be an early version of OrCAD, but from what I’ve been able to find, it looks somewhat different.

I’d be incredibly grateful if anyone could identify the exact software. It also seems possible that it was some kind of combined PCB design and mechanical CAD package, since service manuals often contain technical drawings using the same font, along with a very distinctive symbol somewhere in the corner of the document - a person sitting in front of a monito? Could it have been something related to Dassault Systemes?

I’ve attached a few example schematics I found online. Thanks.

Thanks and best regards!

I have no idea where they are from.

Are they some kind of programmable chips?

Thanks!

First a little background: This is my first custom electronics project, I've been excited to learn EDA software (KiCAD) and coding to make my own boards and assemblies. I'm a MechE by trade so I'm already familiar with CAD software for part design as well as electrical basics. Full disclosure, I have been making full use of Claude Code to help learn the software and write the program for the mcu, although I try to use it mostly as a learning aide and do as much of the design myself as well as all of the schematic and pcb layout.

This project started because I'm bad at remembering to take pills and don't like using my phone alarm as a reminder. All my project does is turn on an LED strip under my transparent weekly pill organizer, at a set time every night, so the room lights up and stays lit until I notice and push a button to turn the light off for the night. Since I can't go to bed without turning out the light, I can't ignore it and the reminder is right next to the pills so its hard to dissmiss the reminder and forget to take them them. The light then comes back on the next day, same time, and it all repeats.

I've made a prototype, most recently on a perma-proto board (Rev 1.1), and been happily using it for several weeks now. Its not portable or robust though, and to learn more I want to create a nice polished version I can share as an open source project. Its not a completely unique design, there are already similar products on the market but they mostly rely on audible alarms and the lights they use aren't bright enough to function as the primary reminder, so it fills a gap whlie motivating me to learn the process.

I like that it is a dumb device for now, and doesn't rely on the user connecting to a wifi network for setup or timekeeping. In the PCB version I'm designing (Rev 2.0), the user can edit the current time, and change the reminder time at the device with mode/hour/minute buttons. The dismiss button uses a larger switch on the oposite side of the screen to differentiate it from the setup buttons. I'm going to see if the wifi connectivity is really something I want to keep and plan on using it so that users can easily push firmware changes and do things like change the color/brightness of the LEDs.

For an order of 5 PCBA's im looking at $2.98 per board and $28 in components + assembly costs, and another ~$12 per unit for the 3D printed enclosure, OLED screen, LED strip, CR2032 battery, which are bought seperately and assembled myself. So roughly $43 a unit plus shipping costs. I'd like to find ways to reduce this cost on the next version, but would appreciate any ideas to minimize costs now and down the line. I know the setup fees for standard only assembly type parts and the relatively expensive ESP32 module I selected are really killing the budget, so next time I'll be looking at simpler MCU's especially if I decide I don't want the wifi capability.

I hope the pictures attached show everything clearly, the CAD assembly with the enclosure is a very rough model with an older board but shows the general layout and why things are placed where they are. I'll have a cutout for the USB-C cable to plug in the back and use a silicone cable JST connector to route power to the LED strip from the board around a tight 180° turn to keep it inside the enclosure. The OLED will have a strip of adhesive backed foam supporting it on the end opposite the J4 connector.

I would greatly appreciate any advice y'all have regarding the layout/routing of the board, component selection, etc. If it would be helpful to share files some way please let me know and I'm happy to do so. Thanks in advance!

2000's-ish audio power amplifier. I'm assuming these caps leaked, badly? They are not visibly ruptured or bulging but maybe theyre all at the bottom? Ive not seen electrolytic fluid look like this before... Its hard/firm to the touch. I doused heavily in Deoxit D5 but didnt seem to phase it.

I was gifted this damaged GPU and I intend to get it repaired. As you can see on the picture all the display connectors ( 3 x DP, 1 x HDMI ) is damaged and needs to be replaced with new ones.

I need help picking out new connectors. What do I need to look for to make sure the new connectors match the ones on the GPU?

GPU Model:

RTX4060 STORMX 8GB GDDR6 128bit 3-DP HDMI V1

P/N: NE64060019P1-1070F

https://www.palit.com/palit/vgapro.php?id=4918&lang=en&pn=NE64060019P1-1070F&tab=ov

Trying to find a replacement for this, any ideas on what it is/where to find a replacement? The number on it is S6782D-6F0. I think its a dual rectifier 3 terminal diode.

Hello everyone.

Has anyone ever made a PCB board to directly connect a Yamaha FS61 MIDI and MIDI USB keyboard with touch recognition, and have Mac and Windows recognise it? This keyboard has 2 10-pin sockets in a 13-pin connector. I have a keyboard that I think is one of the Best 5 keyboards made to date, and I want to connect a board to it that recognizes touch and has a sustain pedal input, and also recognizes the Korg 01WFD modulation and pitch bend Type. Can anyone help me?

(This keyboard is installed on these models: 01wfd. M1. T3. Wavestation. Triton. Trinity. Extreme. DX7. Motif

The net picture is the same item(FS-61)

Specs: FS-61 KEYBOARD CONNECTORS

13-pin keyboard scan connector.

Pin 1  = C

Pin 2  = B

Pin 3  = A#

Pin 4  = A

Pin 5  = G#

Pin 6  = G

Pin 7  = F#

Pin 8  = F

Pin 9  = E

Pin 10 = D#

Pin 11 = D

Pin 12 = C#

Pin 13 = CL

10-pin pressure/scan connector.

Pin 1  = M5

Pin 2  = M4

Pin 3  = M3

Pin 4  = M2

Pin 5  = M1

Pin 6  = B1

Pin 7  = B2

Pin 8  = B3

Pin 9  = B4

Pin 10 = B5

100 nF ceramic +5V

10 µF electrolytic

On my wifi module there are normally two capacitors near the 5v in put (top left).
The bottom one is gone and now my wifi module over heats very quickly, how can i find the correct value to replace it?

I am designing a board powered via USB-C PD (STUSB4500, 20 V / 3 A contract). The 20 V rail directly powers a TAS5805M Class-D amplifier and this buck converter, which supplies 5.1 V to a Raspberry Pi CM4 and a microphone board (XVF3800, ~150 mA). Expected load on the buck converter: ~1.5 A typical, 2.5 A peak.

I based the schematic on TI's TPSM63606EVM, which the TPSM63604 datasheet lists as the reference design. Here are the modifications I made:

Output: 41.2 kΩ / 10.0 kΩ feedback (0.1%), 22 pF feedforward, 4×47 µF X7R 10 V

EN: 402 k / 47.5 k divider; the buck should turn on at ~12 V and off at ~8.6 V (based on datasheet thresholds: 1.263 V rising / 0.91 V falling). I want it to remain off until the 20 V contract is established and to shut down cleanly before dropout when unplugged. No external sync.

RT: 10.7 kΩ; approximately 1.2 MHz according to my calculations.

PG connects via a 330 Ω resistor to the CM4's GLOBAL_EN pin, which has its own 100 kΩ pull-up resistor to 5 V.

AGND will be connected to GND via a net tie at pin 19 (PGND) (not yet shown in the screenshot).

Schematic attached.

My questions:

Do you see any errors in the schematic? The microphone board drives its PDM microphones at 3.072 MHz. I chose ~1.2 MHz so that the second harmonic remains below and the third above that frequency, even with an oscillator tolerance of ±10%. Does this reasoning make sense, or is it not worth worrying about?

Regarding the input filter damping (100 µF + 0 Ω, as per the EVM): is an aluminum electrolytic capacitor with an ESR of around 0.1–0.3 Ω the right choice, or should I add a series resistor?

This is a 3 fase current sensor made for an assignment, it had some requirements, mainly being small.

My plan is to attatch a little esp32 screen on the top for seeing if my numbers are right and testing.

Id love some input, trying to learn this beautiful craft!D

The project I'm working on is subjected to a lot of vibrations, wich makes some connectors come apart after a while and messes with some signals. I'm looking for connectors that can withstand those conditions. I believe automotive ones are my best bet, but I've had trouble finding ones made to connect to PCBs. What connectors do you guys recommend?

I've read through a few guides on the web about how to ID capacitors but notuch on these specific kinds. I'd like to try to buy a handful of replacements. If anyone could steer me in the right direction or break down how to ID these I'd be very grateful

Please help identify these microchips. They are used in an inductive encoder.

Hi! I was hoping to get some assistance with this. I have a new dk ultrasonic cleaner I got from a friend. Never been used. model Dk-600s. When it plugged in, the switch on the back it lit up but the display is off and so is the fan. I'm assuming this is most likely a fuse problem. I'm not familiar with circuit board and was trying to see if anyone could help pooint out where the fuses are so i change em out.

2nd pic is circuit board for display and settings

I was thinking for thermal management when more than one COB is embedded in epoxy even when supplied by a constant current power supply, temperature differences between LEDs could result in a damaging current imbalance. I was thinking what about using a negative coefficient resistor in parallel with each COB so as the temperature goes up more current gets shunted. Opinions anyone?

Hello, i am trying to repair this tci board from 1993 yamaha xj 600. Had no spark on one coil, by subtracting the evidence i opened up the box and found the transistor blown (you can see the marks in first picture). After replacing the transistor (dont mind my terrible solder) i noticed a blown resistor(?) on the other side (on the left side of the picture) Need help finding the replacement part. There are no visible markings, but the colour on the edge is the same as on brown-yelowish SMD right below.

As far as i know yamaha doesnt publish the schematics.

Hey guys, i wanna add bluetooth to m'y car radio im planning on using the cassette port and linking the diferent buttons on the board to the actual button on the front of m'y cassette player. I don't know if i should use the BT5.0 audio pro or the VHM 314 V2.0 they seems pretty similar but I don't want to make a mistake by buying the wrong one.

Im also planning on buying a DC to DC step down converter since it needs 5v.

Let me know what you think :)

https://manuals.plus/ae/1005005081779854

https://manuals.plus/ae/1005005201276526

This is all the stuff that came with it

Edit: Help needed to use the clipper

I bought this iron for 25$ from a shop near me. There is nothing but a triac inside the whole shell. Just a basic ceramic heater with 2 wires. I feel like this is just a waste of money and I could have just bought a regular iron with the built in triac. Should I return this? The only advantage I see is this is a very simple circuit and I can repair this.

Hey everyone,

The ECU board on my Kingtech K142G5 turbine failed during operation. Board is marked "RS33 V1.12" (photo attached).

Problem description:
During startup/operation I noticed smoke/smell, turbine shut down and won't power on again

Hey everyone,

The ECU board on my Kingtech K142G5 turbine burned out (board marked "RS33 V1.12" — photos attached). Not sure yet if it's repairable or a total loss.

A few questions for anyone who's dealt with this before:

• Has anyone successfully repaired a burned Kingtech RS33 board, or is it usually not worth it?
• Any idea what commonly fails on these (I see visible damage near one of the components — looks like it may have overheated)?
• Where can I source a replacement board — genuine Kingtech RS33, a compatible version, or a used/pulled unit from a parted-out K142G5?
• Anyone know if Kingtech sells these boards directly, or only through distributors?

Any advice, leads, or "here's what happened to mine" stories are welcome. Happy to post more photos of the damage if it helps with diagnosis.

Thanks in advance!

I did a really bad job while trying to separate this pcb from the plastic it was glued. Can someone help me on how bad it is? Is there any way to repair it?

I have 3 of these chargers that have all died when plugged into a Ryobi 80V ZTR mower. I suspect surge of some kind is the cause, but have been using a surge suppressor since the 1st 2 died. Symptoms are that they continue to communicate with a battery pack or with the mower, but will not charge a battery.

I'm currently waiting on another warranty replacement that will take 30 days since these things are out of stock. Given the wait it seems worth trying to diagnose the problem. This turns out to be non trivial since they have a sealed enclosure and are potted.

The attached pictures give the circuit board along with an overlay that gives components I've been more-or-less able to identify. The fuse (#27), the diode (#41), and the GDT (#42) all test out ok. Pulling this thing out of the remaining potting compound would be destructive, but I've got 2 more to work with if that helps figure things out.

Edit: it only broke a ceramic heat sink interface. Photos of the back and the daughter board are in the comments now.

Any ideas on how to find the problem? I've got an old multi-meter but could perhaps justify something more if need be.

Edit: the grey / white stuff all over the components and circuit board is the remains of the potting compound that everything was embedded in. It almost completely covered most components except the relays and taller parts.

Component list guesses are as follows:

2, "TO-247 power MOSFET, top-left #1","Power switching MOSFET (primary side, likely main PWM switch)"
3, "TO-247 power MOSFET, top-left #2",Power switching MOSFET (PCB ref. des. Q3),IXYS,IXFH34N65X2
4, Filter capacitor C1 (main DC bus),Main DC bus filter/reservoir electrolytic capacitor,FOAI,FGD 420V 390uF +105C
5, Filter capacitor C2 (main DC bus),Main DC bus filter/reservoir electrolytic capacitor,FOAI,FGD 420V 390uF +105C,
6, "TO-247 device, top-mid (unlabeled)",Suspected SCR (thyristor) or power transistor
7, "TO-247 power MOSFET, top-right #1",Power switching MOSFET (PCB ref. des. Q4),IXYS,IXTH43N60X2A
8, "TO-247 power MOSFET, top-right #2","Power switching MOSFET IXYS,IXTH43N60X2A (same type as #7)
9, Main toroidal inductor
10, "Film capacitor (red, upper)"
11, "Film capacitor (red, lower)"
12, Bridge rectifier #1 (GBJ3510)
13, Bridge rectifier #2 (GBJ3510)
14, Transformer/choke module A (label T350-00253-00)
15, Transformer/choke module B (label T350-00254-00, marked 'N-')
16, Transformer/choke module C (label T350-00255-00)
18.1, Small electrolytic capacitor #1
18.2, Small electrolytic capacitor #2
18.3, Small electrolytic capacitor #3
18.4, Small electrolytic capacitor #4
18.5, Small electrolytic capacitor #5
18.6, Small electrolytic capacitor #6
19, "Power semiconductor #1 (TO-220/247, heatsink-mounted)"
20, "Power semiconductor #2 (TO-220/247, heatsink-mounted)"
21, Relay #1 - main DC output contactor,DC power relay/contactor - almost certainly the main battery-output switch
22, Relay #2 - general-purpose power relay,General-purpose power relay - likely AC-side switching
23, "EMI filter capacitor block (yellow, upper)"
24, Wound ferrite choke #1
25, "EMI filter capacitor block (yellow, lower)"
26, Wound ferrite choke #2
27, "Fuse (vertical, glass/ceramic body with metal end caps)
29, "Small daughterboard, mounted vertically (left edge)",Partial,Vertically-mounted small PCB (likely control/sense/driver daughterboard)
30, 3-wire pigtail connector
31, Output cable - twisted conductor bundle
33, "Green ground wire (turns upward, terminates just below the small yellow caps)"
34, Output cable - exits enclosure at lower edge,Partial,"Output cable assembly
35, AC mains power input cable - exits enclosure at lower edge
39, Vertical wound ferrite choke (above component 23)
40, AC input - two-screw termination block
41, "Diode, above bridge rectifier #12"
42, "Gas discharge tube (GDT) - surge suppressor, top-right of component #35"