Brads Electronic Projects Forum

First I want to say this project is pretty epic and I´ve been working on the table and matrix. But when finally everything was connected and I turned the table on nothing happened at all. So that´s why I´m here to see if I made a mistake or just something really stupid

So first of all I created the matrix with Blue LEDs (http://iteadstudio.com/store/index.php? ... cts_id=101) connected a four battery holder to the plus and min on the board, connected two buttons for mode and select. Connected all the cathodes and anodes of the matrix and programmed the chip with version 2 with a pickit 2 and connected every potentiometer.

So when I placed all four batteries nothing happened, not even a blinking row or a single LED and that's where the hard part is, I don't know where to look or if the board is working at all.

I measured a couple of things first: I receive 6.2V from the batteries, this gets transformed to 2.5V in the converter and when I measure a random point on the matrix with a multimeter I get 0.0V-0.5V. First I thought I made some bad solder points and soldered everything better on bought sides, but no changes. I even removed the mode and select button to focus on the screen. I could remove the potentiometers to only have the matrix connected

Hopefully you guys can help me and here some pics of the set up and board. For more information or pics just ask Thanks!!!

Hi cnribbens and welcome to the Forum..

Looks like you've got some strange voltages? I would start with checking the voltage at this pin first, and let us know what you got?.

OK, I measured the voltage on the right pin and it´s 2.55V and thanks for your help!

No worries well you should have 5volts output at that pin, What are the part numbers on that regulator? its abit hard to see from the pictures.

L7805CV is the part number

It certainly is the correct part, there should be 5volts on that output line.. I suspect you might have a short?
All I can say is double check all your connections, and make sure none of the pins on all of the chips are shorted?.
Maybe Brad might have some other ideas he can add?.

I think I´ll also remove the potentiometers and then see if something changes because then I know for sure it´s not the buttons-controls. But there isn´t much before the convertor only the batteries and the capacitors.

Yeah its worth a try removing the pots and retesting the voltage at the convertor (voltage Regulator).
It sounds like a case of elemination, I wouldn't rule out the capacitors either though, as they can cause alsorts of issue. I guess you have them the correct way around?.

Ok I finally have some progress. I removed the potentiometers, but that didn´t solve anything so I went back to the regulator and capacitors and I discovered something weird but promising:

When I resolder the center leg of the regulator I see quickly the start screen where you select how many players and then I see a nine or six (I guess it's a nine). So then I thought I solved the problem by resoldering but that's not the case. When I turn off and on the game five times it stops working and goes back to the same problem as before. When I resolder the center leg again it works again, but after five times on/off it stops working again.

So I guess it's a bad solder point (not likeley because I've resoldered the thing multiple times and not even touched it) or bad regulator or maybe bad capacitor. I checked to see if the capacitors are correctly placed but they are the minus image/line on the capacitor is on the right side. So when I resolder the leg, the legs get heated and maybe works then, or I change the voltage or something. So this at least is something that makes things easier for you guys

Oh and when it's doing something the power from that pin is 4.5V and the middle line on the photo was not working because the cable was not connected, so the nine is showing properly now.

Thanks for the update cnribbens, I would expect a voltage between 4.5v - 5v on the output from the regulator.
Im glad that you have something working now, maybe it is a fault with the regualtor?. I guess the only way we will know is if you replace it?

Very sorry for the late reply here - have been quite busy these few days.

Great to hear that the circuit is working (at least with the numbers) but is everything else working now? Can you play the game etc...

Also - what is your power supply rated at?

Thats the other thing I was thinking about yesterday? if the supply voltage from the four 1.5volt battieries is 6volt and drops to a threshold that the 5volt regulator cant handle then that could give issues with the regulator..

Most regulators need a min of 1.5volt above there min working condition. for example a regulator marked up as a 5volt regulator would need a min of 6.5volt on the input side, maybe 7volt in some other cases.

That's right, I forgot that you were using the four batteries. As long as they are good batteries then all should be fine with your 5v regulator.

Having said that, it should still run fine at 4.5v.

Thanks for the feedback, I'll order a new regulator, so that will take a few days . And then I can reconnect the buttons and try again. I guess it's correctly that the game goes to the nine because there are no buttons connected and this results in presses or no presses.

When I can start the game then I will reconnect the potentiometers again and should it work great!

I'll keep you updated!

And luckily the regulator is only like 40 cents.