On Tuesday, 27 August 2019 10:39:00 UTC+1, wrote:

Thank you everyone for the amazing help so far. I'm learning so much with this.

I feel like I should've perhaps mentioned that I'm pretty much a beginner when it comes to circuit boards. I've replaced fuses, capacitors and resistors before, after doing some research and finding the correct replacement parts, in order to bring back life to old/broken appliances/toys.

useful to know

Also, something else to note is that the local (Cape Town, South Africa) place where I get all my electronic parts is Mantech (https://www.mantech.co.za).

A lot of parts can be taken from dead e-junk.


I've also followed the advice to remove the remaining epoxy from the chip and look at it under a magnifying glass (unfortunately I don't own a microscope).

I'd approach it by looking at the circuit connected to it. That usually makes it clear what a part is.



@Phil: If I understood you correct, you are saying the because of the blown part, the opto is likely blown as well? If so, which opto should I try to replace it with:
https://www.mantech.co.za/Stock.aspx?Query=817+optoand

Unfortunately I have no idea what happened as I got this from someone that was throwing it out, since they had already replaced it. I'm trying to see if I can fix it.

With mains stuff it's useful to test it by running it in series with a filament lamp if there's a possibliity of shorting.


Also, we have had load shedding happening in the past, which would some times have caused voltage spikes when the power came back on.

Lots of mains appliances consume a large current surge at switch on, together these reduce mains voltage rather than cause a voltage spike or 'surge'. 'Surges' is one of those topics on which plenty of misinformation is believed.

Don't know if that could've cause something like this to happen? I know people have lost appliances to that, but not sure if it could be related.

to all 3 of those points, I doubt it.


@whit3rd: So you reckon, I just try to replace the blown part with a TL431 (any particular one from the list? https://www.mantech.co.za/Stock.aspx?Query=TL431and) and then also replace the optoisolator (any particular one from the list? https://www.mantech.co.za/Stock.aspx...=817+optoand)?

what caused what to blow?

I'll do a check of the diodes. Would testing in circuit be sufficient or should I remove the diodes from the circuit for testing?

It varies. In-circuit testing will sometimes tell you they're ok, sometimes not. Far quicker than taking time out of course.


NT