# Projector Keep Tripping



## RyanP.Joll (Jun 7, 2020)

Hi,

I haven't recently been given a projector because it was 'broken' as It wouldn't turn on! When I first opened it up, the first thing I noticed was that the fuse has blown - I replaced the fuse and it turned on! However, when you press the on 'button' it caused my electrics to trip which is very odd! I have done some research into this and have found out it could be due a faulty capacitor. I have also looked into getting a replacement part but unfortunately the projector is discontinued so the part isn't available. 

This is the part that seems to keep causing the projector to trip after a process of elimination:




On the back there is a what a believe is a 'metal protector' that is soldered all the way round the circuit board. Do you think this is whats causing the electrics to trip and what would you say is the best way to go about this?

Thanks,


Ryan.


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## DrewE (Jun 7, 2020)

The metal shield (to prevent excessive RFI emissions, primarily) is not the cause of your problem. The circuit board appears to me to be a little switching power supply, and the big capacitor would be the main line-side capacitor and probably (though not certainly) is not the root cause of the problem. If you do want a replacement of the large capacitor, it's a 220 uF, 450V electrolytic capacitor with a 105 degree temperature rating; they would be readily available from any electronics supplier (and probably come in a few different physical configurations). Take care to observe that the polarity is correct when putting in the replacement or you'll be in for a very rude surprise when you plug in or turn on the projector.

As I said, though, I would not guess that this particular capacitor is the root cause of your problems. Rather, I would suspect either a bad solder joint (as many of the joints on the board you pictured look quite questionable to me and may be intermittent), or a problem with something else consuming more current than it should and causing the power supply to shut down. For the latter case, a likely candidate is the lamp or the lamp driver circuit; a discharge lamp such as most projectors use, as it wears and gets old, can get harder to start and cause problems or damage, which is one reason they have a timer for lamp life on most projectors. The other main reason is that old lamps get increasingly likely to suddenly self-destruct (explode) when starting, which is not exactly an ideal situation to encounter.


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## RyanP.Joll (Jun 7, 2020)

DrewE said:


> The metal shield (to prevent excessive RFI emissions, primarily) is not the cause of your problem. The circuit board appears to me to be a little switching power supply, and the big capacitor would be the main line-side capacitor and probably (though not certainly) is not the root cause of the problem. If you do want a replacement of the large capacitor, it's a 220 uF, 450V electrolytic capacitor with a 105 degree temperature rating; they would be readily available from any electronics supplier (and probably come in a few different physical configurations). Take care to observe that the polarity is correct when putting in the replacement or you'll be in for a very rude surprise when you plug in or turn on the projector.
> 
> As I said, though, I would not guess that this particular capacitor is the root cause of your problems. Rather, I would suspect either a bad solder joint (as many of the joints on the board you pictured look quite questionable to me and may be intermittent), or a problem with something else consuming more current than it should and causing the power supply to shut down. For the latter case, a likely candidate is the lamp or the lamp driver circuit; a discharge lamp such as most projectors use, as it wears and gets old, can get harder to start and cause problems or damage, which is one reason they have a timer for lamp life on most projectors. The other main reason is that old lamps get increasingly likely to suddenly self-destruct (explode) when starting, which is not exactly an ideal situation to encounter.



Thanks for you reply! There is another circuit board that I believe is the lamp circuit board (which I can get a picture of tomorrow), whenever I unplug this from the projector - the electrics are still tripping. Which I know this doesn't mean that particular part isn't tripping the electrics but it proves that something inside the power supply module is tripping the electrics as when I remove this, it stops the projector from tripping but of course the projector then won't turn on!

Im not sure whether its a dead projector thats worth repairing or possible to.


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## RyanP.Joll (Jun 7, 2020)

RyanP.Joll said:


> Thanks for you reply! There is another circuit board that I believe is the lamp circuit board (which I can get a picture of tomorrow), whenever I unplug this from the projector - the electrics are still tripping. Which I know this doesn't mean that particular part isn't tripping the electrics but it proves that something inside the power supply module is tripping the electrics as when I remove this, it stops the projector from tripping but of course the projector then won't turn on!
> 
> Im not sure whether its a dead projector thats worth repairing or possible to.



Also adding onto this! Since the projector won't even turn on ( you plugin it in and it will trip). Surely its got nothing to do with the lamp? Or am I wrong in saying that?


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## DrewE (Jun 7, 2020)

What exactly do you mean by "tripping" in this case? The fuse blows? The power supply shuts itself off uneventfully?

It does seem the power supply is having troubles, from what you're saying and the testing you've done. I'd try reflowing the solder joints on the card first. After that, it's standard switching power supply troubleshooting, which should be fairly straightforward for most anyone who deals with electronics repair these days; there's nothing really special about this one vs. any other one, or at any rate I'd be very surprised if it were. Capacitors can be a frequent point of failure, to be sure, but there are others common ones as well, such as the switching transistor (very often a MOSFET) or snubber/freewheeling diode.

As to whether or not it's worth repairing the projector, if it's a standard lower-priced projector, such as is found in a classroom or office meeting room or similar, it's probably not economically sound to pay someone to repair it, but there's certainly no harm in seeing if you can get it working if you're doing so on your own time or for your own edification. For high-end projectors I suspect the economics are completely different (and replacement parts are presumably more available).


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## RyanP.Joll (Jun 7, 2020)

By tripping if I mean, it trips then MCB in the house. Doesn’t even trip a RCD plug for some reason.

It’s a low end projector that I’m trying to repair for my own education to learn from and see what’s similar with these and other projectors.

I know it’s not worth sending it to a professional because it’s not something that I’m that bothered about saving but it’s a learning curve and if I can repair it then great! If not then there is no loss.


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## FMEng (Jun 7, 2020)

The power supply module is available.
https://www.aliexpress.com/item/32952219161.html

Whether an old projector is worth gambling the money is hard to say. Consider the cost of a lamp when that eventually fails, because they can be quite expensive.


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## RyanP.Joll (Jun 8, 2020)

FMEng said:


> The power supply module is available.
> https://www.aliexpress.com/item/32952219161.html
> 
> Whether an old projector is worth gambling the money is hard to say. Consider the cost of a lamp when that eventually fails, because they can be quite expensive.


Yeah I saw them on AliExpress but I know it’s definitely not worth paying that much for. Especially since it’s something that might not even be real if I did think to buy it.


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## Crisp image (Jun 9, 2020)

If you plug the power board in to the mains without the output attached (so it i just the board on the bench) does the CB trip?


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## RyanP.Joll (Jun 9, 2020)

Crisp image said:


> If you plug the power board in to the mains without the output attached (so it i just the board on the bench) does the CB trip?


Yeah! If if only plug that board in with no other board it still trips.


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## Crisp image (Jun 9, 2020)

Then there is your problem isolated to the power supply. 2 choices really. Figure out what is the problem or replace the power supply. I know which way I would go.
Regards
Geoff


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