Need help identifying value of this bad SMD cap.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

Okay Budm, I get new results.

When the Blue LED is on, the collector measures 1.45VDC. When I switch it off and measure the collector, I get 0.45VDC but it's counting down. After a few minutes, it reads 0. However, if I switch on the mouse and the blue LED does not light up and then I turn off the mouse, the collector measures 0.004VDC.

[shortchange]

Re: Need help identifying value of this bad SMD cap.

http://img0051o.psstatic.com/1026616...interface-.jpg

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

Yup, that's mine.

The collector goes to the positive terminal (anode) of the LED. It goes through a diode and possibly a few other things. I think I know what this transistor does. I think it's what makes the LED blink when you move the LED. With the mouse, if you flip it upside down, the LED flashes. It doesn't do that now that the cap is missing.

[budm]

Re: Need help identifying value of this bad SMD cap.

Yup, that's mine.

The collector goes to the positive terminal (anode) of the LED. It goes through a diode and possibly a few other things. I think I know what this transistor does. I think it's what makes the LED blink when you move the LED. With the mouse, if you flip it upside down, the LED flashes. It doesn't do that now that the cap is missing.

The NPN Q5 is connected as Common Emitter, so when it is turned on it should sink the LED current to GND to turn on the LED, so the Cathode (-) of the LED should be connected to the Collector, the Anode (+) should be connected to current limiter resistor and then to the Boosted B+ (Probably around 4VDC) or so. The LED should not be always on to save the battery power, there must be some thing that detect the movement of the mouse to turn on the LED. At this point you can try using cap from .01~.047uF in place of the broken cap to see what will happen.

http://www.eecs.tufts.edu/~dsculley/...nsistors1.html

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

Thank you Budm! I will give it a shot and see what happens. I will also read the links you have posted once I'm done.

[stj]

Re: Need help identifying value of this bad SMD cap.

what chip is in this mouse?
there is probably an example schematic in the datasheets.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

From the last article you linked to, when they say:
"Here, the control signal will turn power on and off to the load. Note that the load sinks current into the NPN transistor when it's made to act as a switch."

Does that mean the transistor provides a ground connection to the load? I'm specifically asking about the "load sinks current into the NPN transistor" statement.

[budm]

Re: Need help identifying value of this bad SMD cap.

"Does that mean the transistor provides a ground connection to the load? I'm specifically asking about the "load sinks current into the NPN transistor" statement."Yes. Sink mean the one end of the load is connected to the VCC, the other end is connected to one end of the switch (Transistor, Relay contacts or MOSFET), the other end of the switch is connected to GND to complete the current flow, this can also be called LOW side switching.
The other way to supply the current to the load is to Source the current (or HIGH side switching), the VCC is connected to the switch (Transistor, MOSFET, Relay contacts), the output side of the switch is connected to the load, the other end of the load is then connected to GND to complete the circuit.

http://electronics.stackexchange.com...high-side-load

http://www.eetimes.com/document.asp?doc_id=1272366

http://www.infineon.com/cms/en/produ...3dfda067250219

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

what chip is in this mouse?
there is probably an example schematic in the datasheets.

Two chips that I can see. One is a 20-pin chip that says,
NRF M
24L01+
1049CY

The other one is an 8-pin chip that says, (kinda hard to read with my magnifying glass):
24AA32A
SN (some symbol) 1114
(some symbol) 83C


I believe the NRF24L01's datasheet is here:
https://cdn.badcaps-static.com/pdfs/...19552854b8.pdf

And the 24AA32A's datasheet is here:
https://cdn.badcaps-static.com/pdfs/...9f3f041a3a.pdf

I believe the NRF24L01 is a 2.4GHz wireless transceiver and the 24AA32A is an i2c serial EEPROM.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

"Does that mean the transistor provides a ground connection to the load? I'm specifically asking about the "load sinks current into the NPN transistor" statement."Yes. Sink mean the one end of the load is connected to the VCC, the other end is connected to one end of the switch (Transistor, Relay contacts or MOSFET), the other end of the switch is connected to GND to complete the current flow, this can also be called LOW side switching.
The other way to supply the current to the load is to Source the current (or HIGH side switching), the VCC is connected to the switch (Transistor, MOSFET, Relay contacts), the output side of the switch is connected to the load, the other end of the load is then connected to GND to complete the circuit.

http://electronics.stackexchange.com...high-side-load

http://www.eetimes.com/document.asp?doc_id=1272366

http://www.infineon.com/cms/en/produ...3dfda067250219

Thank you. So whenever the load sinks current into the transistor, it will always be an NPN transistor and whenever the load sources current from the transistor, it'd be a PNP transistor.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

So, every time I try learning about transistors (I've tried a few times but I didn't know enough about electricity to understand them, I know a bit more now), I've always seen people use switches to control them. I know transistors can be used as an amplifier or a switch. Right now, I'm just worried about the switch mode ones. We could use something like a PIC to control a transistor, right? But a PIC, we can use the I/O lines like a switch anyway. The only time we'd want to use a transistor there with a PIC would be if we wanted to control a high amount of current, is that right?

And a little off topic here, I'm not sure I can word my question in such a way where it's clear, but I know we need a complete path for the voltage to flow through a circuit. From what I've read, a battery supplies energy to move a charge from it's low energy, low potential terminal to the high energy, high potential terminal.

What if I have a complete circuit with a battery but I take another battery and hook only one end of the battery to the circuit? Would the battery eventually drain and the energy in the one battery will move to the high potential terminal in the other battery? Or because the other battery isn't completely hooked up to the circuit, only one of the terminals, would the energy in the battery never get used?

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

The NPN Q5 is connected as Common Emitter, so when it is turned on it should sink the LED current to GND to turn on the LED, so the Cathode (-) of the LED should be connected to the Collector, the Anode (+) should be connected to current limiter resistor and then to the Boosted B+ (Probably around 4VDC) or so. The LED should not be always on to save the battery power, there must be some thing that detect the movement of the mouse to turn on the LED. At this point you can try using cap from .01~.047uF in place of the broken cap to see what will happen.

http://www.eecs.tufts.edu/~dsculley/...nsistors1.html

I just found a 110 nF capacitor, same colour and it appears to be the same physical size as the one attached to Q6. That would be .11 uF, right? And that'd be too big to try using, right? I'd want something that was 10 to 47 nF in size, right?

[budm]

Re: Need help identifying value of this bad SMD cap.

You can try it, you measure the resistor that is parallel with the cap to be only 400 Ohms so the time constant will be very short with 0.10uF cap.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

I put the 110 nF MLCC cap in, no change. I noticed something funny though....when I press on one of the crystals a bit, it will almost ALWAYS light up when I turn it on. I'm wondering if, when in my fit of anger, after throwing the mouse on the table real hard, I somehow managed to break the crystal inside. I have an oscilloscope but I don't think it works right anymore. When I was trying to learn how to use it, I watched a short tutorial and a few videos. I tried using it to diagnose a bad circuit board that had a built-in power supply. When I was testing stuff by the power supply side, it sparked really bad and made a loud bang. I think I ruined my scope. Not 100% sure how to test it. I got a signal generator (old school). When I hook it up to the scope, most of the functions appear on the screen but I don't think they're right. Like when I have it set to square wave, it should be a certain voltage on the graph but it's way off. Maybe it'd be enough though just to see if the crystal is producing a waveform or not.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

When I hook a 1x probe to the adjustment connector on the scope, I get a signal, which is good. It's a .5v signal and when I have the scope set to .1v per division, I see that it's taking up 5 divisions, so I'm guessing it's good.

When the blue LED is lit, on one crystal, I'm reading a voltage drop of 0.672VDC (black probe on negative terminal of crystal, red probe on positive terminal of the crystal). With the other crystal though, I always get 0.000VDC. Would that imply I broke the one crystal that's reading 0.000VDC? Or does that just mean the one crystal might not be being used right now so it's not getting any voltage? Maybe it's for a different part of the circuit or something that isn't active at this moment?

[budm]

Re: Need help identifying value of this bad SMD cap.

Possible that the Xtal is damaged and also the MLCC (easy to damage), and also cracked solder joints.
Can you read the printing on the Xtal?

[budm]

Re: Need help identifying value of this bad SMD cap.

BTW, you also broke the Ferrite on the right inductor (L4: 1R8?):
https://www.badcaps.net/forum/attach...4&d=1450117322

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

Possible that the Xtal is damaged and also the MLCC (easy to damage), and also cracked solder joints.
Can you read the printing on the Xtal?

What's the Xtal? The crystal? If so, yes, I can read it. It says:
CMT-LLAZ1C. I'm not so certain it's the crystal anymore. When I checked the two terminals against the battery ground, I got no readings. But I think I discovered something. When I was using the needle probes (when the mouse was on, no blue light) to check the voltage going to the transistor after replacing the cap, when I pushed down hard on the base, the blue light clicked on and when it was on, I ran my finger over the sensor and the blue light flashed, like it does when I'm moving the mouse. Maybe when I removed the transistor and put it back on, I didn't get all the pads soldered properly? I'm gonna take my iron and touch it to each pin to see if that fixes the issue.

[Spork Schivago]

Re: Need help identifying value of this bad SMD cap.

BTW, you also broke the Ferrite on the right inductor (L4: 1R8?):
https://www.badcaps.net/forum/attach...4&d=1450117322

We noticed that but because the copper wrapping was still good, we thought it was fine. Do we need to replace that as well? It appears it's just the top plastic part that's broke...

[budm]

Re: Need help identifying value of this bad SMD cap.

Xtal = Crystal, That is why you see Crystal designator as X1, X2, ETC.