I have a box of childrens toys of the sound making kind. And among them is the "Vtech precomputer developer" I opened it, and to my surprise I can't find the meat of the machine. My guess is that its around the screen, because that's the only place that I have not checked. Anyone here done one of these? Here are two pictures taken of it. in the picture of it opened you will see a circuitboard. all there is behind it are contacts for the bottons in the first picture. any sugestions would be nice. I feel like I'm over my head.
picture.(http://0319062104.jpg) (http://0319062107.jpg)
I've never bent this specific machine but i have come accross a few machines by grandstand / IQ builders where all the electronics are round the back of the screen and the rest of the case exists just to support the keypad. In fact once i had a wierd babies laptop thing where i couldn't find any electronics whatsoever, i can only assume that it was 'black blob' chips actually inside the screen assembly.
One thing to be careful of on a lot of Vtechs. They often have a low value resistor inside a piece of clear tubing on the board. This acts as a kind of fuse and will blow if you even look at it in a funny way. Just bridge it and the thing will leap back to life.
Pictures didn't show up there, which is odd
I opened it up the back and started to play with all the components, and the only part that does anything is a black chip that shorts it and you have to restart it every time. everything else is really small. Lets see...three black chips labeled as: LH5S4R40( it makes noise when you touch the connectors) 84CF33T, and 8018J. 4 capacitors, about 18 resistors. the "black blob" which I assume is what holds the information. I also see the "fuse" thing you were talking about. I have a basic knowlege of bending, and this thing has so many small circuits. So it proves to be most difficult. any cool tricks that I can utilize for this project?
in my experience 'black blob' circuits are rarely good for bending apart from the fact that they tend to have a clock speed resistor that can be replaced with a pitch pot, but not always.
I suspect most of that circuit is the power supply and speaker amp.
V-tech's are wierd in that some have very high build quality and circuit design and can take a lot of punishment where as others look like they were built in a shed in someones garden in china. Some of the cheaper ones tend to be useless.
Quote from: Circuitbenders on March 20, 2006, 04:06:38 PM
One thing to be careful of on a lot of Vtechs. They often have a low value resistor inside a piece of clear tubing on the board. This acts as a kind of fuse and will blow if you even look at it in a funny way. Just bridge it and the thing will leap back to life.
Yeah, this worked to bring my alpha desk back to life, good advice.
thanks for that advice on the resistor in the tube :) fixed up one of my alpha desks... :)