RIP "Kid's Way" Keyboard?

[omgphil]

Let me start by saying hi!


My name is Phil and I have been making chiptune for quite a few months.
www.myspace.com/omgphilmusic

Seems like a really good community you have here so I thought I would ask for help. Sorry for being so n00by.

I recently started bending, and after a fried kids keyboard followed by some soldering practice and a successful bent furby, I felt pretty confident. I went to a local carboot and picked up loads of goodies including a Kid's Way toy keyboard which was overpriced but beautiful so I couldn't resist. I opened it up and found some amazing bend points, distortion, loops etc. However after crashing it a few times it wouldn't turn back on. I tried everything, resoldering the battery joints, speaker, replacing the batteries, turning it off and on again several times and no luck. But then it did turn on briefly but made some pretty awesome distorted sounds and died again. Now its totally dead. Have I killed it or is there light at the end of the tunnel? (I miss it already.)

Sorry for the essay.

[catweazle]

hi,

difficult to say if its really dead. The integrated circuits are damageable on some pins. The oscillator pins (there where the crystal or the resistor is connected) are very weak protected against voltage overloads. So if you connect a voltage on these pins (>5V or so) it can demage the clock circuit inside so the toy will never work again. Always use a resistor (>100 Ohm) for bending. Take care that you never connect voltages >5V to the integrated circuit on all pins, most ICs (integrated circuits) have protection diodes inside to protect against electro static discharge/ "high" voltages but not all have them. "black blops" are very demageable (i've freid some McDonalds toys too)
Safty bending tip:
Measure the voltage on the bend-points to ground (-)  if the voltage is above 5V don't use it!
Don't connect the oscillator pins with other pins.

Maybe some ICs have a programming pin, that means if under some circumstances you have entered a "program" or "debug" mode and maybe you have "reprogrammed" it with a empty code -> original code is overwritten/deleted.

But there is a little hope, check the diode after the power input connector (if there is one) it's a part (mostly black or transparent) with an ring on one side -this part can be demaged (input voltage polarity protection) or a capacitor is blown which often results in a short circuit. Measure the resistance (OHMS) between + and -  if its around 0 Ohm a capacitor (around the power input)  is blown (short circuit).

I hope that was not too technical

Gtz
Eric

[ne7]

in addition to catweazles excellent post - also look for largish resistors on the board - some toy keyboards and kids alphabet desks have these and they fry REALLY easily - u can just bridge the connection (bypass the resistor) and it'll work like new

[omgphil]

Thanks for all your help, i tried these things and they didnt work, but it woke up after a couple of days!

It keeps on dying like that so I figure I've got to be careful which points i clip together.

[Circuitbenders]

If it woke up after a couple of days theres a possibility you just needed to discharge a capacitor somewhere on the board by shorting its pins together, although i can't imagine there's any caps big enough on a kids way keyboard to actually matter so i could be talking rubbish.

[omgphil]

How big are we talking?

I tried discharging some of the larger resistors but that didnt seem to work. Since then its pretty easy to crash and doesnt wake up for a couple of days. Driving me crazy!

[catweazle]

There could be only big capacitors on the power input to stabilize the operating voltage, maybe the biggest one is dead, try to desolder it (should work without it) and or replace it with an equal value or higher if you do not have the exact value lying around, the exact value for the capacitance doesn't really matter, but be aware of the voltage value that should be equal or higher. Typical values is 100uF / 16V   

PS:
resistors do not hold electrical charges, you don't need to discharge resistors 

[omgphil]

Fixed it

I found that short circuiting a particular resistor makes it work again.

Whats more, I've found some good crashes and glitches.

I'm sure you're all sick of being asked this, but how do I find the pitch resistor? Any tips? Will post photos of the board if helpful.

[catweazle]

As mentioned from Circuitbenders at
http://www.circuitbenders.co.uk/forum/index.php/topic,441.0.html

A lot of replaceable resistors can be found with the lick your finger and poke the circuitboard technique. If something happens narrow it down to which solder point is creating the effect and replace that resistor, if it is a resistor.

Otherwise , find a likely looking resistor and temporarily bridge it using a pot of equivalent or higher value. When you turn the pot and the resistance goes lower than the bridged resistors value, the current will take the path of least resistance and you'll get a rough idea of what would happen if you replaced that resistor. Remember that you'll only get the effect of what would happen with a LOWER resistance. To find out what will happen with a higher resistance you'll have to actually remove the resistor from the board.

It really helps if you have some kind of electronics knowledge in order to select which resistors to try but as with most things in circuitbending, stay away from where the power comes into the machine. Bear in mind that most circuits probably won't have any resistors that you can just replace at random and create good effects. Unless its an analogue machine i'd be surprised if anything has more than one or two, if that.

If there is a pitch-resisitor you find it that way (pitch goes higher if you touch it)
But sometimes a crystal or tank circuits is used for clock generation.
The pitch - resistor is always placed near the black blop/main controller IC.

A picture where helpful   

Good luck!

[omgphil]

Okay so I've finished soldering all the points with switches, pots, resistors etc., whats the best/cheapest tool to make holes in the casing?

[Circuitbenders]

umm, a drill?

[omgphil]

Aha okay that sounded kinda stupid admittedly.

I mean is there any drill i should look for in particular on the internet that's ideal for the job. Links would be kinda cool (:


Thanks for being so patient everyone.

[Circuitbenders]

well, you don't need anything specific. I usually use a power drill i picked up for about £15 from a hardware store with a HSS drill bit set i think i got from cpc electronics, but you can get such things in lots of places as they are nothing special.

If you are intending to do a lot of circuitbending then a hobby drill like a Dremel with a selection of bits like drills, grinders, circular saws and sanders is invaluable. Something like this:

http://www.dremeleurope.com/dremelocs-uk/Category.jsp;jsessionid=01F62BB48FFCD2BDD30AADBCE0736C69?&ccat_id=471

Real Dremel models aren't cheap but in my experience its not worth getting a cheap copy.

[omgphil]

That's helpful, thanks.

I'm pretty sure there's a drill in the shed somewhere so I'll check out getting some decent drill bits on the interweb.