I'm troubleshooting a reel controller board for an IGT slot machine. The digital section seems to be dead. There is no USB communication, PC or utility program for flashing firmware do not see it but they do see good/working boards. I noticed the waveform on the crystal is very erratic/asymmetrical/glitchy on the bad one compared to the nice even waveform on a good board. My question is would this most likely be caused by a bad crystal or something gone bad in the circuit loading it down? I'm attaching a couple pictures of my scope probing the good and bad boads.
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adjust the timebase on the scope to see less waves but in more detail.
but crystals do degrade,
i often change them on old amusement gear - i like to change the small ceramics too - incase they are the cause.
it's probably not usb, just using usb cables to save money - sega does that and uses usb cables for RS485 serial comms.
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Yesterday I swapped crystals with a working board, got a nice clean waveform but the board still doesn't work. I then put the crystal from the bad board onto the good board and also have a nice clean waveform and that board still works as well. Maybe I had a bad ground or something?
Also at my work I only have an old 20mhz scope. I've been here 22 years and it was here when I started. I don't really use a scope often enough to budget for a new one. I also have a Fluke 97 scope meter rated at 50mhz so that gives me a little more detail.Last edited by Keshenatech1; 02-27-2024, 09:20 AM.Comment
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fluke 97 is nice when you can see it, those EL backlights are crap.
i have a 97 put away - it was my first scope
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Hi just wondering if anyone knew the part ID for the crystal Oscillator on the Steam Deck i've attached an image of the broken part on my board.
Thanks...02-02-2024, 12:56 PM -
Hi friends of electronics
What you see in the video and pictures attached is the circuit for charging the batteries of a DC motor.
The problem is that this circuit cannot charge the batteries (3 1800mAH NiMH batteries) any more. When the circuit was OK, its green LEDs lit up one at a time to show that the batteries have charged more. But now that the circuit is flawed, LEDs light up as you see in the video and at the same time successive beeps are heard.
Please help me fix this circuit.
(the datasheet of the IC: https://pdf.datasheet.live/28... -
Hello friends,
Its been a while, i wish you an happy new year 2025 !
I have this laptop doesn't start, power light up a second when pluging USB-C charger.
Laptop take 0.11A.
All signals and voltages before SLP_S4# are OK but no SLP_S4# , S3...
I get no oscilation on XTAL 32.768 KHZ
Battery is not charging but charging led is here.
PCH heat at 30° approximatively. (with no heatsink)
I think this crystal might be dead, i have only boardview giving me this: XTAL 32.768KHZ 12.5PF/20PPM.
It's a 2 pins Crystal.
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Hello.
I have seen a short circuit tester made with 3 * 9V batteries, a voltage limiter component and a resistor connected to the probes of a multimeter.
The theory is that the meter becomes sensitive enough to read very low resistances and the lowest resistance to ground on a circuit is likely to be a short circuit in that area.
Link
The Amazing $1 Short Finder Upgraded! Convert ... - YouTube
https://www.youtube.com/watch?v=0eixDdCpiO4
My multimeter isn't normally sensitive to very small resistance, but when I put a 1 mega ohm resistor... -
Hi,
I am repairing a ups which doesn't turn on ,it has the following ICs:
SG3525 used to drive inverter mosfets.
couple of uc3483, one for the power supply and another to drive a big mosfet at the output stage(i think the technique is called boost)
A LM358 and TL074 for control mechanism and of course the uController.
The SG3525 is shutting down every time the ups is turned on.
I want your help to know the function of LM358 and TL074 in the system.
I reverse engineered the LM358 circuit and i think that one of the block(A) is used for battery level...
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