Bongo Fury

As related on another thread (speed alert) I have obtained a small kit to build a speed alert device. This is the first time I have tackled this sort of activity but I thought it would be fun. And so it is however having finished all the assembling, soldering etc I have now reached the testing stage and I could use some knowledgeable input. As an ex programmer I am accustomed to debugging code and have tried to apply similar principles to this testing. The kit uses a microprocessor which via various buttons to control modes drives 3 display leds to give the speed display. The kit comes with the microprocessor pre-programmed.

In accordance with the instructions I have verified that there is +5v at a particular pair of pins on the micro. After this when connected to a 12v supply the displays should light with the default config. As they dont light I reasoned that I should check continuity between the micro pins via the printed circuits and up to the led displays. I've attempted this with a multimeter and it seems to be ok.

I've emailed the kit supplier (in Australia) and await their response but I wondered if anyone here could suggest anything else I might try while waiting.

The kit came with very detailed diagrams and photographs - it all originally appeared in a magazine SILICON CHIP.

Ron

I hope you cleaned the pcb tracks with a fibre-glass pencil prior to fitting components and soldering them in.
And that you used a micro-soldering iron with a tiny tip.

Now you need a magnifying glass and a bright light.

Double-check that there are no solder bridges between pins and that there are no dry joints.

Then check again, each one, from a different angle.

Then check that you inserted any "polarised" items (IC's, transistors, electrolytic capacitors, diodes) the correct way round.

If any of these checks reveal you have done something wrong, just pray that you have not duffed any components by doing so.

I speak from considerable experience as an expert - who has made all the mistakes (and not learnt from them!).

Thanks for the fast reply Pippin. I didnt know about the fibre glass pencil so no I didnt do that. In checking for continuity I placed the probe on the tip of the component wire and reasoned that if the next point along the printed circuit registered ok then the joint between pin and print should be ok and the track working. I found some that were not ok and resoldered and retested.

I used a small magnifying glass and got close up to a table lamp and checked all round each joint. The ones that failed as above usually appeared like a doughnut around the pin.

The instructions pointed out polarity where it mattered and I followed the instructions.

When I embarked on this project it was with the realisation that 'fools rush in' however thats how I started programming and in due course I made my living from it!

I dont know if I've duffed any components along the way - I guess that someone doing a lot of this would have the gear to check resistors, capacitors, etc, etc and since I dont it maybe that I've reached an impasse.

Ah well......

Ron

Hi ronhud take heed of pipin ....wise words indeed ....i bet pipin has, like me, draws and cupboards full of part started / salvaged and dead circuit boards, radio hams just cannot throw anything away! with me its an illness, but what the hell ..i have the room! anyway have you had a practice taking components out , cleaning the board and refitting the component back ? before getting stuck in to the assembley ? what are you knocking up a binary counter? are you looking at the alternator output square wave/ pulse ? tell me more ...oh and why all this is your speedo duff ? also what type of soldering iron have you used leaky, earth ? wattage ? have you cooked the components some components are near indistructable ! and some are "pow" then gone in a second, thanks Rich.... ps some IC's require you stripping down to your Y fronts, clipping a jump lead to your left ear lobe and then to a 6 foot spike banged into the ground... then wet the spike and surrounding ground for a week, ...then you MIGHT be ok

Hi Rich I really appreciate Pippins words.

When I was working I did on occasion use a suction type device to remove solder - this was making up 9 pin connectors for pc use.

I have used a fine tip Weller 12w soldering iron on this project.

I started into this because within a week of getting my Freda I had picked up 3 points for speeding and from then on realised that I found it v difficult to stay under 30 in my Freda. Extra height above the road, more comfortable driving position - I dont know but i wondered if a device was available to beep if a set speed was exceeded. I looked around a lot but the only way I could see was with certain type of sat navs and apart from the cost of these I didnt want to be paying subscriptions. And I enjoy using maps! However I came across an article on the web taken from SILICON CHIP mag describinbg the building of just what I fancied. Although it included getting a pulse from magnets on a drive I checked with the author and he confirmed that it would accept the electronic pulse driving my current speedo. So as I said on an earlier post -fools rush in -
and I ordered the kit. If it becomes one of the never finished jobs then so be it but I've enjoyed the challenge. It may be that more experience and tools are needed than I thought.

Ron

I have a binger that came on my old town ace and when attached to the back of the speedo assembely it beeped at 100 kph townace long gone but still have it
If its any use to you your welcome to it

Thanks for the offer. I'm looking for something that can be adjusted while driving and switched if need be.

I think Pippin has covered most of it. I wouldn't worry too much about the fibre-glass pencil thing. As long as you have a good connection between the board and the component then things should be fine.

Most likely explanation is either a solder bridge or something in the wrong way round (check the IC is the right way up!).

If you were really heavy-handed you might have overheated something when soldering. ICs in particular can be damaged by too much heat.