logical fault finding - ten tips for when things go wrong
When everything works there are no worries, but
when things go wrong where do you start? When you are under pressure and the
screens are black, and everyone is looking at you, it's tough to think straight
and the danger is you just grab stuff and start unplugging, and make things
work. Here are some possible tips.
There are some basic rules about fault finding
that will make it more likely that you will find the fault quickly and be able
to work around it in a hurry.
1. Think before acting. The temptation is to dive in and do something, but pausing for a moment to think may well allow you to dive in and do the RIGHT thing.
2. Question your assumptions - there's no point in saying "Well, I KNOW that DVD player is OK" when you have selected the DVD input and are getting a blank screen. Test every assumption by experiment.
Try connecting outputs directly to monitors to see if you get a picture, try swapping inputs - does the fault follow the swap or not?
3. What did you just do? Usually the problem will be that you did something that caused an unexpected effect. Retrace your steps and undo whatever you just did.
4. Actual equipment failure is quite rare - operator error or misconnection is much more common.
5. This is when you are going to REALLY wish you had labelled all your main cables, especially the long ones.
6. If you have actually lost live video during a performance, and need to get something up on the screen quick, then consider removing things in the chain till you get the most direct connection. Ultimately this may mean connecting your VCR output directly to the projector input, at least until you get a chance to do something about it.
7. OK, now down to the logical bit - You start at one end of the chain and work back along checking every connection, every input and output. Once you STOP getting a signal (or START getting one) you know you have found the problem item or cable, and can swap it out or bypass it.
You can either start at the end (projector) and work back, or start at the input (camera) and work forward.
What is especially useful for this is a battery powered LCD monitor that you can plug in as you go down the chain, to check where the signal is getting to.
8. Remember to mark suspect cables or connectors IMMEDIATELY otherwise you will waste time retrying stuff you have already tried.
9. Swapping out gear or cables is the quickest way to bypass any fault. Always make sure that you have spare cables, or have worked out some alternate way of connecting your critical path items. Design your system, then think "What would I do if this gear/cable failed?"
10. Try to only change one thing at a time then test - if you change too many things you won't know what fixed it, or you might fix it, but then unfix it without realising.
1. Think before acting. The temptation is to dive in and do something, but pausing for a moment to think may well allow you to dive in and do the RIGHT thing.
2. Question your assumptions - there's no point in saying "Well, I KNOW that DVD player is OK" when you have selected the DVD input and are getting a blank screen. Test every assumption by experiment.
Try connecting outputs directly to monitors to see if you get a picture, try swapping inputs - does the fault follow the swap or not?
3. What did you just do? Usually the problem will be that you did something that caused an unexpected effect. Retrace your steps and undo whatever you just did.
4. Actual equipment failure is quite rare - operator error or misconnection is much more common.
5. This is when you are going to REALLY wish you had labelled all your main cables, especially the long ones.
6. If you have actually lost live video during a performance, and need to get something up on the screen quick, then consider removing things in the chain till you get the most direct connection. Ultimately this may mean connecting your VCR output directly to the projector input, at least until you get a chance to do something about it.
7. OK, now down to the logical bit - You start at one end of the chain and work back along checking every connection, every input and output. Once you STOP getting a signal (or START getting one) you know you have found the problem item or cable, and can swap it out or bypass it.
You can either start at the end (projector) and work back, or start at the input (camera) and work forward.
What is especially useful for this is a battery powered LCD monitor that you can plug in as you go down the chain, to check where the signal is getting to.
8. Remember to mark suspect cables or connectors IMMEDIATELY otherwise you will waste time retrying stuff you have already tried.
9. Swapping out gear or cables is the quickest way to bypass any fault. Always make sure that you have spare cables, or have worked out some alternate way of connecting your critical path items. Design your system, then think "What would I do if this gear/cable failed?"
10. Try to only change one thing at a time then test - if you change too many things you won't know what fixed it, or you might fix it, but then unfix it without realising.
Posted: Sat - September 6, 2003 at 09:44 AM |
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This site contains my personal views, ideas, tips, tricks and rants about doing live video, IMAG or graphics at live events on a very low budget. They are published as I get time, in a style closely approximating a weblog. Dave C.
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My name is Dave Chalmers and I live in Edinburgh in Scotland, UK. My background is in Electronics, but for 10 years I have been helping to put on live video at events in central Scotland in my spare time. Through the course of these events, nearly all on very constrained budgets, I have learned a few things about what works and what doesn't. While I would not claim to be able to give you all the answers, I can at least help you avoid some of the mistakes.
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Total entries in this category: 16
Published On: Jul 06, 2006 11:37 PM
Total entries in this category: 16
Published On: Jul 06, 2006 11:37 PM