this post was submitted on 10 Mar 2026
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A bug in the system. (infosec.pub)
submitted 1 week ago* (last edited 1 week ago) by tuff_wizard@aussie.zone to c/askelectronics@discuss.tchncs.de
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Merlin rollerdoor (Australian garage door brand) stopped working, when investigating I found a bug had shorted itself across an IC (labeled HVS004).

Luckily Merlin sells the whole replacement unit for only $449AUD. Before I pull the trigger on that I was wondering if anyone here could advise me on my chances of success if I just replaced the burnt bit.

I’m happy with larger electronics but I’m struggling to even identify any fuses on the board to check.

I’m also unable to find a replacement IC online as the code on it seems to be associated with some kind of blue LED. (I also don’t know for sure if the IC needs to be programmed or if it is just standard)

The back of the board is fine, just thru-hole solder connections.

here are some more photos(new link, should work now), hopefully in good quality.

Thanks in advance

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[–] partial_accumen@lemmy.world 20 points 1 week ago (1 children)

For others looking at this, the damaged IC is silkscreened as IC7 (red square in my edit of OPs pic). OP, the fuse on this board is the green SMT device (that I put a green square around). Here's the sales sheet for that fuse.

OP you gave a part number for the blown IC as HVS004, but from what little I can see in the picture I'm wondering if its something else. I've put a BLUE square around another IC8. I'm guessing thats in the same family, from where it is in the board. However, I can't see what the part number is on that one. Can you share that one?

[–] tuff_wizard@aussie.zone 3 points 1 week ago (1 children)

hey mate, I've added changed the link to the album. those two both have the HVS004 code on them which you can see in one of the new images

[–] partial_accumen@lemmy.world 2 points 1 week ago (1 children)

Much better pictures, thanks! I had suspected that both those ICs work together (and it looks like they do), but I couldn't find any part that matches it in any searches. It could be a specialized ASIC they made, or they could have bought proprietary marked ICs specifically to prevent the kind of repairs you're wanting to do.

Apologies I can't help further, you may be stuck buying a new board. Maybe keep the dead one around in case you need a replacement part in the future.

[–] tuff_wizard@aussie.zone 2 points 1 week ago* (last edited 1 week ago)

Ok, thanks. Considering no one here can identify the part and I don’t have the skills to work out exactly what it does, I’ll have to fork out the money. I suspect you are right and it’s just an off the shelf part with a custom code on it to trip up DIYers.

I know enough to know they’re making a fat profit off that module though.

[–] Nawor3565@lemmy.blahaj.zone 4 points 1 week ago (1 children)

It seems like the Imgur album only has a photo of the back of the board. I think HVS004 might be the wrong number, can you take a close up photo of the chip (and surrounding circuitry) with a flash for a clearer view?

It's also weird that a bug could have fried itself across a chip that only runs off a few volts. "Bug zappers" usually use at least a few kV. Maybe that IC runs off the 33v line or it was a particularly wet bug, but I suspect that might not be your issue.

[–] tuff_wizard@aussie.zone 1 points 1 week ago

hey mate, I've updated the imgur link with more, better quality photos. it might not have been the bug but it sure did short as you can see from the images

[–] mvilain@fedia.io 2 points 1 week ago

Had a slug short out the power supply on an ancient Doorking security door. They don't make that version any more so we upgraded both systems. Now AT&T is charging $350/mo just for the phone line, so these systems have to go. Don't know what the HOA decided, but at least it won't cost a monthly fee. Let's just hope the HOA President stays in office as we use her Internet connection to run the entire complex's network.

[–] tofubl@discuss.tchncs.de 2 points 1 week ago

Looks like a switching regulator. Why there are two of them I don't know, but all those electrolytic caps, inductors, and beefy diodes around there are very telling.

The fuse is labeled as PTC so should be a resetting type that does not destroy itself on overload.

If the problem was indeed a bug shorting out the IC itself you probably have a good chance of getting it back by just replacing the IC, if you can identify it.

[–] Notsosuperfloh@discuss.tchncs.de 2 points 1 week ago* (last edited 1 week ago)

I'd desolder the burnt ic and check if there is a short across the 16v caps. if there is no short power it and check if any of the 16v caps has any voltage on them. if theres no voltage on any of them also remove ic8. if you have a lab psu set it to 5v and current to 0.1 amp and inject it to the 16v caps and if you're lucky it powers up. if not slowly turn the voltage up until something happens. if it's working get a buck converter and solder the input to the 35v cap set it to to the same voltage as the psu and solder the output to one of the 16v caps.

id say 5v should do, as those caps go directly to ics. if both, ic7 and ic8 work independently from each other probably need to inject 5v to at least two of those 16v caps.