Have I fried the circuit board?

[GB452]

So I shall start by saying I am a HUGE novice in all of this. But I do love to tinker.


Thanks to an unneeded PC speaker wire that I cut open to access the white/red wiring, I have a very crude way to provide direct recordings of all the various sounds from this toy.

It's not pretty:

But it has yielded some nice results from a first try this morning:

zyuranger_capture.avi - YouTube


However just a moment ago, one of the exposed speaker wires touched the area right below (where the red/black wires are near the on/off switch) where the yellow wires go to the circuit board, and now the toy seems "dead". No sound, no lights... Not really sure WHAT happened...(the circuit board has those two wires as "P23 BAT" and "BAT" respectively... so the wire touching caused some type of short?).

Here is a photo where I've unscrewed the battery compartment to show the board:

I'm not entirely sure if the wire (seen to the far left of the photo) touched just the black wire with red stripe, or the full red wire... or both... which I would assume could create some very wrong "connection" between the two points.


Is there ANY way to get it working again?

 

[enjunear]

From looking at the lower image, the red/black wires should be "BAT" and "BAT-", for "Battery" and "Battery, Negative terminal". I believe P23 corresponds to a pin or via near the IC in the center of the board (under the ball of black potting material). I'm not sure what voltages are present on your speaker/microphone wires, so it's tough to say. I'd hazard a guess that the errant wire caused you to short-circuit the battery, which could upset other circuits (put a voltmeter across the red & black wire to check that the battery still is providing power). Also, the wire could have connected +battery voltage to some trace on the board that wasn't supposed to have +battery volts on it (and subsequently fried a circuit, somewhere).

For such a simple board, I think it's probably dead if you can't identify any simple issues like no supply voltage reaching the chip in the center, etc.

 

[GB452]

Thank you for a prompt reply. I took a closer look and yes, there is just "BAT-" and "BAT+" underneath. I don't own a voltmeter at present (wish my grandfather was still alive, he'd have one... most likely three), but I suppose I can get one soon enough (I assume this will do just fine?).


Hypothetically speaking, if the voltmeter does register voltage, what would the next step be? If not, then as a "dead" board... there isn't a way to "revive" it, so to speak?

If nothing else .... I've learned a good lesson about making sure wires don't slip and touch what you don't want them to.

 

[enjunear]

Thank you for a prompt reply. I took a closer look and yes, there is just "BAT-" and "BAT+" underneath. I don't own a voltmeter at present (wish my grandfather was still alive, he'd have one... most likely three), but I suppose I can get one soon enough (I assume this will do just fine?).


Hypothetically speaking, if the voltmeter does register voltage, what would the next step be? If not, then as a "dead" board... there isn't a way to "revive" it, so to speak?

If nothing else .... I've learned a good lesson about making sure wires don't slip and touch what you don't want them to.

That multimeter should be just fine for most everything you'll need to do in the next many years (I have a few low-dollar meters in various toolboxes for odds-and-ends testing needs, and they work just fine). Multimeter = voltmeter, ammeter, ohmmeter, etc... all rolled into one = what you are planning to buy :smile:

First, determine what the proper voltage should be. Looking at your first image, I see two AA batteries, so in series that would be 1.5V * 2 = 3 volts. Turn off the power switch to the board (should disconnect all circuits from the batteries, giving you an "open circuit", and will not load down the batteries (which could distort your measurements). If the batteries read 3V, then check the voltage at the BAT+ and - inputs, confirm 3V. Then, flip the power switch. This will apply a load to the batteries (current will be drawn by the circuit). Check to see if 3V is still present on the BAT+/- inputs. If so, then you're getting power to the board. If the voltage droops significantly when you apply a load, then something is drawing a lot of current (i.e. a low resistance path), which is not a good sign in low-power electronics like this toy would be.

As for repair... unless you are a skilled electronics technician with the right tools, then I'd say your chances are slim and none. Check out the resistors and capacitors, if any looked burned or broken, then you might be able to replace them, but again, that's a looooong shot. I'd probably just buy another toy to rip apart.

If all else fails, use your voltmeter to poke around and check out voltages on various points in the circuit. Just be careful that you don't let your probes slip and short adjoining traces together... you can get just as nasty of an effect as having an errant wire brush across traces :shock:

 

[GB452]

Thanks once again for your input and help. Purchased the multimeter.

Just note of clarification: AAA batteries, not AA.

From the time of posting, I have poked and prodded around, and nothing appears burnt or broken. I'm not going to say I'm particularly skilled in this area.. but with the right equipment and reading up, I do master new "tricks" with ease.

In the end, as just got my second one in the mail this evening... I may just save up (these go for $60-80 or more on eBay) enough for a third. As for what I do with the "dead" one if it is totally unrecoverable.... part of me wondered if with enough knowledge, tinkering, modifications, equipment, resources and time... if I couldn't somehow modify it into a functioning cellphone. Though I supposed it'd lack a screen, unless I figured some area for it, and would be pretty "thick" (see photos) for a phone used in 2012.

 

[mvs sarma]

It might be discouraging for you, but,with a COB as major part of the circuit board, perhaps not much can be done.

 

[enjunear]

Thanks once again for your input and help. Purchased the multimeter.

Just note of clarification: AAA batteries, not AA.

From the time of posting, I have poked and prodded around, and nothing appears burnt or broken. I'm not going to say I'm particularly skilled in this area.. but with the right equipment and reading up, I do master new "tricks" with ease.

In the end, as just got my second one in the mail this evening... I may just save up (these go for $60-80 or more on eBay) enough for a third. As for what I do with the "dead" one if it is totally unrecoverable.... part of me wondered if with enough knowledge, tinkering, modifications, equipment, resources and time... if I couldn't somehow modify it into a functioning cellphone. Though I supposed it'd lack a screen, unless I figured some area for it, and would be pretty "thick" (see photos) for a phone used in 2012.

I think your plans to turn this device into a cellphone are a bit grandiose. The circuit you currently have is a very simple system that takes some entered commands/values, and plays out some sound clips. There is nothing there that functions equivalently to a cellphone; you'd need the entire radio unit, not to mention a system that is authorized on an existing cellphone provider's system. Also, these devices have to be qualified to some regional testing authority, like FCC in the US.

Maybe this is what you were thinking, and I just missed the concept in your prior posts. The easiest way to make that device into a cellphone would be to rip the guts out of it, take a working cellphone, remove the electrical components from it, and install them into the Mobirates plastic case (as you mentioned, cut a hole for the display), and then tie the buttons into the existing keypad interface. It's not a simple undertaking, but it could be do-able with some heavy research and tinkering.