PCB assembly discussion

[adminbear]

I'm going ahead with my construction, but can i safely assume (after a set of random tests) that the holes in the PCB are plated through?? Do I need to solder resistors on both sides?

Thanks!
jack

[Tony]

They're through hole plated so you only need to solder one side.

[Riddler357]

Hello World!

Hello everyone My name is Victor and had a couple of questions about this project. First just to let you know that i have been building electronic devices for years and everyone of them worked the first time, example 8x8x8 led cubes(not powered by arduino boards) larson scanners, and different robots. This project seemed to be pretty easy project to be put together. I got up to the first test part and found that the LED's were not working except for the ir one. So did some trouble shooting and didn't find anything out of the norm. The leds work because i always check LEDs before i put them into a project. So i was wondering if you had a wire diagram of your work. I could just use the PCB but would like something i can follow. I would really love to get this working.

Thanks Victor

[Tony]

If the IR led is working the controller is probably OK. There was a problem using the notches to identify polarity and the instructions were amended to mention it though you've probably built it since then.
There's really not a lot that can go wrong here if the PIC is working, could you measure current being drawn and the voltage across the LEDs and let me know.

[vtluu]

I received my kit today and started assembling it, but then got to the LED step and ran into a problem. 1 of the 5 LEDs has the flat side on the opposite side from the rest. Suggestions?

I went ahead and mirrored the anode/cathode layout of the other 4 for this one, but please let me know if one was actually supposed to be 'off'.

I had the exact same issue, and dealt with it the same way you did (which appears to be the correct answer).

[vtluu]

I've managed to get up to first "power it on stage" but am not seeing any light from any LED (which one is supposed to light up?). Unfortunately, my MM doesn't do mA (just amps), but I get a flat 0.0 across R28 when plugged in. I've run across the board testing everything I can think of, and everything seems to be correct. Would you mind if I emailed you some macro shots of my work so far and maybe you can spot something I've missed? Or perhaps give some additional troubleshooting hints on what may be wrong?

I'm currently at this stage and in the same predicament, though I've done less debugging so far (will next have time to spend on it this weekend).

I'm worried I may have really borked things, because in the process of soldering on the surface-mount IC, one of the pads came off the PCB. I *think* it was intentionally shorted to the other pads in which case I could just substitute a solder bridge, but I'm not sure.

Worse comes to worse I hope I can purchase a replacement PCB + first-step components (not including the expensive stuff, namely the tubes) and start over.

In hindsight I should have taken detailed photos of back of the blank PCB so I would know for sure what's an inadvertent solder-bridge (two close solder points shorted together that aren't supposed to be touching) and solder points that are close and connected by design. Tony, is there any chance you could provide such a photo? Thanks!

[Tony]

Have a look in the 'troubleshooting' thread for the PCB layout. Could you check the voltage across the LEDs and at pin 14 of the PIC. There's very little to go wrong in hardware that can prevent the LEDs working. The PIC can hang before that stage though if it doesn't receive a signal from the sensor - without any data there's nothing to display so they're switched off.

Check first:
MPSA42 and 92 transistors haven't been mixed up
Voltage across LEDs
Supply to PIC (though if the IR LED is working it should be on)
Bridges around the SMD IC, the DHT11 and the 5k6 resistors.

Let me know the results.

[Tony]

Just realised that I replied to the wrong question

Just to clarify, is your problem no current at all being drawn?. (we fixed that one via emails)

I've managed to get up to first "power it on stage" but am not seeing any light from any LED (which one is supposed to light up?). Unfortunately, my MM doesn't do mA (just amps), but I get a flat 0.0 across R28 when plugged in. I've run across the board testing everything I can think of, and everything seems to be correct. Would you mind if I emailed you some macro shots of my work so far and maybe you can spot something I've missed? Or perhaps give some additional troubleshooting hints on what may be wrong?

I'm currently at this stage and in the same predicament, though I've done less debugging so far (will next have time to spend on it this weekend).

I'm worried I may have really borked things, because in the process of soldering on the surface-mount IC, one of the pads came off the PCB. I *think* it was intentionally shorted to the other pads in which case I could just substitute a solder bridge, but I'm not sure.

Worse comes to worse I hope I can purchase a replacement PCB + first-step components (not including the expensive stuff, namely the tubes) and start over.

In hindsight I should have taken detailed photos of back of the blank PCB so I would know for sure what's an inadvertent solder-bridge (two close solder points shorted together that aren't supposed to be touching) and solder points that are close and connected by design. Tony, is there any chance you could provide such a photo? Thanks!

[vtluu]

Thanks for the quick reply Tony. I didn't have my multimeter with me at the time so I couldn't measure current or anything, only visually inspect everything. Unfortunately I won't have time to pick up this project again until Saturday... But when I do, I'll check everything you mentioned and report my findings here.

[Riddler357]

Hello World!


Hello again,

So here is what i did, I really didn't care for the LED's being there in the first place, so i went ahead and did the rest of the project without the LED's. Got everything in and and did the second part of test, so when i plugged it in, again nothing lit up:( at this point i figured that the LED's are part of the circuit. So i started to test with the circuit using the amp scale. When i touched one end of my meter to where the power side of the LED was ..the nixie tube lit up and started to go through its numbers. So I put the LED's back in and when i plugged it in nothing came on. I tried different LED's same size and again nothing happened. I put some 100k resisters in and it started to light up again. I really don't care for the LED's being there, but if i have to have them there why does it only work when i put a dummy load on it?

Thanks
Victor