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Topic: Scoreboard project: Random segments lighting up (Read 2259 times) previous topic - next topic

MrGibbage

I want to make sure I am ordering the right this. How's this:
Docooler-1pf-100nf-Capacitor-Assorted-Assortment

Would someone mind explaining to me what the functional difference will be in the circuit? Also, how confident are you guys that making this swap will fix the problem?

LarryD, when you say "soldered right at the pin", do you mean the same hole in the perfboard as the pin, or is the hole next to the pin good enough?

By the way, the caps I have installed do indeed say "0.1 uF" on the side. Of course, that doesn't do me any good since they are the wrong type.

2016-03-11%2011.33.18.jpg


2016-03-11%2011.35.16.jpg

Zapro

Would someone mind explaining to me what the functional difference will be in the circuit? Also, how confident are you guys that making this swap will fix the problem?
Dave just did it:
Dave Jones (eevblog) explains decoupling-capacitors.

// Per.

pwillard

#17
Mar 11, 2016, 01:47 pm Last Edit: Mar 11, 2016, 01:48 pm by pwillard
AHA!

I gave you credit for having a tiny green 0.1uF cap near the header connector...

Wrong location anyway...  I stand by what I said.  Place the 0.1uF cap as close to the IC's Vcc and GND pins as possible...   I have often solved this on bad PCB designs by attaching the capacitor leads directly to both pins on the underside of the board.

MrGibbage

Oh yeah, I meant to mention that yesterday. That green thing by the header pin is just a jumper wire. I can see how it would look like a small cap though.

Boy, I am really hoping that I have the same luck and that when I get these caps in, all of my problems will be solved.

larryd

The picture in post 13 is what you need.
Butt solder the capacitor to the same pads as the pins on 17 (+5)  an 14 (LGND).

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MrGibbage

#20
Mar 11, 2016, 04:45 pm Last Edit: Mar 11, 2016, 04:54 pm by MrGibbage
Larry, do you have any pictures you can share of a bypass cap soldered in place? If I understand you correctly, I will need to solder the cap on the bottom side of the board to make it happen. The socket for the TPIC covers the holes too much on top to get the cap in there. I guess it would be OK to solder it on the bottom, but I don't think I've ever seen it done like that before. Also, can you explain the "butt solder"?

larryd

#21
Mar 11, 2016, 08:44 pm Last Edit: Mar 11, 2016, 09:18 pm by LarryD



See:
www.thebox.myzen.co.uk/Tutorial/De-coupling.html


"butt solder"
Just solder to the existing pads on the bottom pad pins 17 to 61-15-14


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MrGibbage

Well, I put the .1uF caps in ("104") and I still have the same symptoms. I soldered them on the bottom of the board, and got them right on pins 17 & 15.

I also watched the video about bypass caps, and based on what I saw there, I also shortened up all of the power wires. I don't know what else to do.

Bypass Cap

larryd

#23
Mar 12, 2016, 03:44 am Last Edit: Mar 12, 2016, 03:45 am by LarryD
It does not appear 14, 15 and 16 are connected to GND, please confirm they are.
Are 6 and 5 connected to ground also?
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MrGibbage

Yes, they are connected to GND. Refer to pictures 12, 16, & 17 in post #3.

larryd

#25
Mar 12, 2016, 03:56 am Last Edit: Mar 12, 2016, 04:10 am by LarryD
Quote
The power for the board comes in on the ribbon cable.
Maybe bring the +5 and GND to your boards with 22AWG wires.
Work on one board at a time..
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larryd

#26
Mar 12, 2016, 04:05 am Last Edit: Mar 12, 2016, 04:06 am by LarryD
Confirm with an ohmmeter (Arduino turned to off) you are using the correct wires in the ribbon cable.
i.e. from pin 13 on Arduino to pin 8 on all registers.
Do this for all other pins.
Use a highlighter, mark off each signal line in the schematic, as you check each signal with an ohmmeter
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MrGibbage

I made a separate 5v and GND power line for the TPIC boards and so far all tests have been satisfactory. I need to more permanently wire it up, but I am feeling good about it.

Thanks for the help, everyone! I'll be sure to come back and let you all know how it worked and and maybe share a pic of it "in action".

larryd

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