Crash Sync cut out problems

[Freddy205]

Hi there I recently built a Crash Sync (Using the pcb layout from John Hollis' site) and it was working fine and dandy. But now I play it and it only works for a couple of seconds after I connect the battery, it works again when I dis/connect the battery again but only for a few seconds! Does anyone know whats going on? Has my 555 chip died?

[jmusser]

It sounds like a good old fashioned dead battery, but you may have already tried a fresh one. It sounds like it has enough juice to power up the circuit, and when it gets to the minimum operating voltage, it dies off completely, then charges up enough to start the process over again once it's disconnected. In my short experience, chips are working or not, and don't "kind of" work. This could also have something to do with one of the two 10uf caps for the power supply, if they're going bad. It could also be something as simple as a bad solder joint off the battery snap to the board.

[Freddy205]

I've already tried changing the battery/10uf caps This is really frustraiting. I just can't find the source of this real strange problem! I have a feeling it may have something to do with my 55 actin more like a monostable than and oscillator.

[jmusser]

It could be so many simple things. It would be worth changing the timer chip, just to rule it out. one thing I have seen (only once) is a bad pot. Sometimes you get a bad one even if it's new, and sometimes it can get dirt in it, and cost intermitant problems. It is sounding like there is something to do with not having a constant voltage source to the timer. What you have to look at, is what has changed since it was working. For ecample, was it working great out of the enclosure, but started having problems once it was in an enclosure? Have you looked everywhere underneath the board for a solder bridge, or a piece of component lead that has sneaked out from under wiring or components to short something out? This could be something that's taking the power to ground somehow. Unfortunately, there are a bunch of variables in these circuits, and the problem could be anywhere. I know it's frustrating because I've been there. The main thing, is to start ruling things out. Know that your circuit is wired correctly, no "iffy" solder joints, nothing grounding out against the enclosure, etc. Read "what to do when it doesn't work" to rule stuff out. The main thing is to get this one ironed out, and it'll make subsequent builds a lot easier to debug. This will end up being a simple error once you find it, and probably something you "knew" was correct and wasn't all along.

[jmusser]

Any luck yet?

[Freddy205]

unfortunatly not! Ive tried changing the power supply caps, batteries and check all the solders but it still does this cut out after a few seconds!