Re: failed PCB circuit - anyone able to have a look? (long shot)

[<xslash@xxxxxxx>]

forget to mention. It also can have a battery backup (12DC) which i have
tried
(without the 230V) and it exhibits the same syptoms



Quoting slashcomfort <xslash@xxxxxxx>:

> I have a gate opener circuit which worked up to a few hours ago.
> Rather than go through the process of sending it back to be repaired,
> I'm thinking it will be a simple component thats gone in it and so
> I'm going to ask those experienced with power supply type circuits to
> see if it obvious. Will send jpg of board to those interested in
> having a quick look.
>
> Nothing looks blown, all fuses are ok, no components looked cooked
>
> The unit takes 230v AC into a toroidal transformer and outputs 12v AC
> (yes, AC). This work ok as when the board fails, i still see 12V on
> the board from this. Somewhere along the line it gets converted to
> 12vDC and 5vDC.
>
> Theres a LED labeled 5vDC that is always normally on, since the fault
> this starts off bright as it should, then slowly fades (after about
> 5 - 30 seconds - the board still works as it should during this short
> period but its not long enough to open/close the gates) - this is
> what appears to be at fault - I beleive the boards brains work off
> 5vDC and its failing.  Also, theres a Normally open switch that you
> press to activate the gate, this read 5v while the LED is bright
> (normal) then just drops to zilch. To me (and i havent done
> electronics for years) primary components not including the relays
> (used for switching motors on/off) are a couple of transisters
> mounted on a heatsink (power conversion?) and a large capacitor.
> Could it be the capacitor has blown and not holding its charge?
> email me for a photo of the board if interested
>
> any help appreciated
>
> thanks
>
> Ade
>
>
>
>
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