Re: Help ID a sot-23 device
Ok, just had a chance to solder in the 470ohm resistor. It did power it on... which was great... but unfortunately it acts just like the burnt component. The menu and start buttons don't function, and it doesn't power itself off as it should.
theagent
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Last Activity: 09-10-2015, 12:36 PM
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Re: Help ID a sot-23 device
Ok, I can try that... do I connect the resistor in series? So like this? [url]https://www.dropbox.com/s/7m1muloh6s581es/RacewheelGND.jpg[/url]Re: Help ID a sot-23 device<br /> <...lGND.jpg[/url]Leave a comment:
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Re: Help ID a sot-23 device
I see. So perhaps the SI2301 mosfet is the correct part, and something else isn't working correctly?Leave a comment:
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Re: Help ID a sot-23 device
But it must be... it powers on, and stays on with the original damaged component. The only problem is that it powers on by itself, and the menu button doesn't function (the menu button is the power button, with the device powered on. Same button).
You know what, I'm sorry, I was wrong... Q3 doesn't go to the IC. I just looked at it more closely and did some continuity tests... it just goes through the resistors, then to the battery. It looks like it's just contained in that little group that I traced out.Last edited by theagent; 07-08-2012, 02:52 PM.Leave a comment:
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Re: Help ID a sot-23 device
At the Drain it's 0V before pressing power... and ~2.3-2.5V when pressing/holding the power button. This is with the Si2301 in circuit.Leave a comment:
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Re: Help ID a sot-23 device
Well, it is doing the switching part... but isn't acting like a latch. It is getting a steady voltage to the gate (or base). I don't really know what else to try. What is responsible for keeping it "latched?"...Leave a comment:
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Re: Help ID a sot-23 device
Ah, that 2SJ243 looks promising. With the Si2301 in circuit, the gate is 4.057V to ~3.0-3.2V with the power button pressed. I don't see it in sot23 package, which is what the part is however....Last edited by theagent; 07-08-2012, 12:52 PM.Leave a comment:
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Re: Help ID a sot-23 device
That makes sense. But the PNP transistor didn't work. Is it possible that it's a PFet? I read this on a different forum:
Remember when I said that the voltage is rising to certain level, then quickly dropping at Q3? This sounds exactly like what's required of the mosfet, according to that quote. And it did in fact attempt to power on with the mosfet I tried. But didn't stay on. Perhaps I just needed a different mosfet....Leave a comment:
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Re: Help ID a sot-23 device
The resistors tied to Q3 go to one of the IC chips covered in epoxy.
U8 is a DC-DC step-up converter
and
U1 is a voltage regulator. [url]http://www.datasheetarchive.com/6206a%20sot%2089-datasheet.html[/url]. The datasheet corroborates the fact the the center pins are connected.
I believe they're both ok.Re: Help ID a sot-23 device<br /> <...age regulator.Leave a comment:
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Re: Help ID a sot-23 device
I traced out what I thought was important... would this help? [url]https://www.dropbox.com/s/535l3gv1b9b6u4f/racewheelboardtraces.jpg[/url]
It's the battery that's connected... the line that says +5v is for the power adapter, which isn't connected.
I also ran the board through Adobe Lightroom and brightened it up quite a bit. [url]https://www.dropbox.com/s/6qqhxomi93bwoj2/racewheelboardBRIGHT.jpg[/url]Re: Help ID a sot-23 device<br /> <...aces.jpg[/url]Last edited by theagent; 07-07-2012, 05:10 PM.Leave a comment:
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Re: Help ID a sot-23 device
With the red probe on Emitter and black on Base, it's showing 0V unfortunately.Leave a comment:
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Re: Help ID a sot-23 device
Well, I went ahead and tried the PNP transistor. It didn't work. No lights, nada. The only other time the wheel lit up was when I used the SI2301 mosfet, but like I said, only for a millisecond.Leave a comment:
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Re: Help ID a sot-23 device
Thank you for taking the time. I'm getting a steady 0.103V from all 4 pins of U1. Do you still think Q3 is a PNP transistor? I believe I found one I can try... it's 45V 500mA bipolar... do you believe that would work?Leave a comment:
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Re: Help ID a sot-23 device
It's actually behaving very oddly. Setting the meter to ohms, it is now jumping up to about 20Mohms, then quickly falling to about 500kOhms then 0L, then jumps right back up in the megaohms, and repeats. That's with the probes on the right side of the cap, and on the collector.
Here's the breakdown.
Meter set to Ohms.
Probe on right side of EC3
Probe on Collector
Jumps to 20-23Mohms, then falls quickly to 500Kohms, then 0L and repeats
Probe on right side of EC3
Probe on base
1.36Mohms,...Leave a comment:
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Re: Help ID a sot-23 device
Seems to be connected yes. The left side of EC3 is connected to the collector with 640ohm between them. No connection to any pins of the transistor from the right side of the cap.Leave a comment:
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Re: Help ID a sot-23 device
Ok, great! Thank you for the help, I really appreciate it. I do have scrap boards. I will have to go through them and see if I can find one that will work. I will report back Thanks again.Leave a comment:
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Re: Help ID a sot-23 device
Oops... ok, desoldered it and tested the pads.
I have ~4.056V for the Base (left), ~4.253 for the emitter (right), and 0V for the Collector (middle/top). Of course the unit wouldn't power on without the transistor in place, but the batteries were inserted, so there was voltage to it.Leave a comment:
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Re: Help ID a sot-23 device
Ok, just soldered it back on and took the readings...
Looks like they're fairly similar at each pin.
~3.580V on the base, ~3.650V emitter, and ~3.555V collector. Thanks.Leave a comment:
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Re: Help ID a sot-23 device
Thanks for the reply. I'm not too experienced... can you tell me how I would test that? From the base to ground I get 23ohms, from base to vcc 0.9ohms, and from vcc to ground I get 23ohms as well. Setting my multimeter to the diode setting I get 0.001V base to ground, and 0.020V base to vcc, and 0.020V with vcc to ground. I get this result regardless of the orientation of the probes (pos to base or neg to base). And it beeps continually, as if it's shorted (and it probably is).Leave a comment:
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Help ID a sot-23 device
Hi. I was hoping someone could help identify this component.
I'm trying to repair an xbox wireless racing wheel that someone had plugged a random power adapter into and blew. The wheel would not power on. I saw damage to this sot23 component and an smd tantalum cap... I replaced the cap and the device powered on... however it powered on by itself, and the middle button which functions as both a power button and menu button wouldn't work properly. It also would not power itself off as it should. My conclusion was that it was this sot23 component for obvious reasons (giant hole).
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