Repairing Lilliput touch controller / Fried Zener - Page 2

rando · 08-12-2004, 09:40 AM

Quote: Originally Posted by Batmanatthenewb

Rando,

My controller died too. Looked at it and there was some indication of the over voltage (compared to the other pictures in this post). I removed the zener and mine still doesn't work. I saw the one side was 5v rail and other was ground. did you just leave the zener off and it worked again, or did you put something in its place until the replacement from Armen got there?

Batman

Once I removed it, the touch kit worked again (albeit unprotected from any kind of power issue). I assume this means the zener fried into a short, or at least a near short. It crumbled into pieces as I unsoldered it. The replacement part was important to restore the limited over / reverse voltage protection.

If your controller isn't working without the zener then I assume you have other issues. It's fairly lucky (in my case) that the zener burned to a short. Once it burns to an open, you'll no longer have any protection and your ICs are next in line to get fried. Check the data sheets on some of those components. They are fairly clear that they cannot survive even momentary spikes beyond 5.5V.

In other words, the zener provides only limited protection and eventually the controller will be killed by errant input voltages.

rando · 08-12-2004, 09:42 AM

Quote: Originally Posted by Curiosity

Well, this is what it looks like when it's shorted from over voltage.

Yep, though mine was much blacker than that. It scorched the circuit board and even melted the solder joints.

superdude · 08-25-2004, 08:38 PM

Quote: Originally Posted by rando

OK, that was it. Who would have guess that the red wire was ground and the black wire was 5v. Apparently the 5v did refer to the zener and thus it was reverse biased ... the planets are aligned again.

Armens replacement zener came in today, it's installed, and my touch controller is safely working again. BTW, the markings CJ5.1 appeared on the part and I conrfirmed it to regulate around 5V.

Thanks to each of you that helped and a special thank you to Armen for providing the replacement part.

Who or what is armen?

archimense · 08-25-2004, 08:50 PM

Got to love the Lilliput controller boards with red for negative and black for positive.

I fried my controller because I assumed they followed standards.

rando · 08-26-2004, 12:26 AM

Quote: Originally Posted by superdude

Who or what is armen?

It might help if you actually read the thread before you post.

Quote: Originally Posted by digitalww

I can probably take this component from one of the bad controllers I have and send it to you, for a $1

What do you think?

Armen

As you can see, Armen is DigitalWW. DigitalWW is Armen. I think that about clears it up.

blackpacu · 03-26-2005, 12:55 AM

I have the same problem with my lilliput.
I have a friend zener diode in the same spot, when i removed it the touch screen started working again.

I have a diode from radio shack part# IN1733A 5.1 V Zener diode

I believe it is a 1 watt diode. where the one that burned out was a .5 watt diode. Will using this diode as a replacement be accecptable?

Curiosity · 03-26-2005, 03:02 PM

That should work fine. It will just take more to blow it, but it will still protect the components.

egon · 01-23-2007, 09:36 PM

I also fired this diode... I power a few different devices off of molex connectors (terminated in barrel plugs) and accidentally plugged one carrying 12 volts into my USB hub. Several toys lost their lives as a result. I further screwed things up by crushing the diode upon removal.

1. I would like to replace it with an identical one, so if anybody can identify it from the pictures in the post linked below i would appreciate it.

2. Will any 5.1v zener with 1w dissipation work? I have an IN4733A.

3. Will running the touchscreen w/o this diode or with an improper one just cause harm to the Lilliput? or will it hurt my mobo?

http://www.mp3car.com/vbulletin/show...ight=datasheet