Repair emergency light  - Page 1
Forum section: electronics / repair

author: Ghoghnoos
author_rank: Newbie
timestamp: January 30, 2023, 06:15:20 pm
content: Hello.Does anyone have a circuit or photo of KM-7655 (Kamisafe) emergency light ?

author: cantata.tech
author_rank: Regular Contributor
timestamp: January 30, 2023, 08:21:28 pm
content: Quote from: Ghoghnoos on January 30, 2023, 06:15:20 pmNo, but if you have a unit, perhaps you could unscrew the unit and upload a photo of the board ?Sometimes it can be very hard for people outside of Japan to get circuit diagrams of products like that, but I'm open to be proven wrong.Is there anything wrong with the unit? or are you looking for it for curiosity ?

author: Ghoghnoos
author_rank: Newbie
timestamp: January 31, 2023, 01:01:40 pm
content: These are its photos. But due to its damage, the wires are disconnected and I need to know how its wiring diagram is in order to repair it.

author: Ghoghnoos
author_rank: Newbie
timestamp: January 31, 2023, 01:04:36 pm
content: Also, the amount of burnt resistance is not known

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 31, 2023, 01:49:06 pm
content: Quote from: Ghoghnoos on January 31, 2023, 01:04:36 pmIt looks like the resistor is in series with the LED and if so that makes it a bit strange that it is burned like that.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 31, 2023, 01:54:32 pm
content: Mass produced devices like that are usually cheaper to replace then to spend time and money trying to repair them. Are the batteries even still good? Chances are that buying new batteries will cost more than the complete device.Manufacturers of cheaply made devices like that seldom provide any schematics so the only way of knowing the value of the resistor would be to find an identical device and open it up and see. Or you could draw a schematic based on the board that you have there, then post it here and someone could give you an educated guess as the value of the burnt resistor. As I said in the first paragraph, it's probably more trouble than it's worth.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 31, 2023, 01:56:45 pm
content: Quote from: Stray Electron on January 31, 2023, 01:54:32 pmI wanted to suggest that too but I don't know op's situation of course. A quick google learned that the thing costs like $10 new.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 31, 2023, 01:56:51 pm
content: Quote from: PA0PBZ on January 31, 2023, 01:49:06 pmI'm wondering if C2 hasn't shorted out and that caused the resistor to burn up?

author: Stray Electron
author_rank: Super Contributor
timestamp: January 31, 2023, 01:59:15 pm
content: Quote from: PA0PBZ on January 31, 2023, 01:56:45 pmThat's true. It might be one of those situations where they can't simply replace it and they HAVE TO fix it. I'm just making the point that repairing it isn't economically justified.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 31, 2023, 02:00:50 pm
content: Quote from: Stray Electron on January 31, 2023, 01:56:51 pmIt looks like C2 is across the low voltage supply, and so is the resistor and the LED. If C2 was shorted the resistor would not burn

author: robert.rozee
author_rank: Frequent Contributor
timestamp: January 31, 2023, 02:02:19 pm
content: i see an AC 110-240v input, and a DC 12v input. i do NOT see any sort of isolation between the two.my first thought is that this is an item that is NOT SAFE TO OPERATE. keep the rechargable batteries and bin the rest.cheers,rob :-)

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 31, 2023, 02:05:36 pm
content: It has a plastic enclosure so reasonable safe to put it up on the ceiling. Not so safe to tinker though

author: DavidKo
author_rank: Frequent Contributor
timestamp: February 01, 2023, 06:46:55 am
content: It seem to me that the electrolytic capacitor is inflated.When you want to change the resistor you need to carefully clean the board from the burned part - it can be conductive and risky to use even after removing the burned part.You can make your own diagram from the board itself (it will be very simple) and then it will be easier to find out the issue. If something went wrong and high voltage was on the resistor, it simply burned. I'm suspicious, that the current was also passing through PCB itself in later stage and created bigger damage.

author: jpyeron
author_rank: Regular Contributor
timestamp: February 04, 2023, 06:27:56 pm
content: Think about, is the cost of re-failure in an emergency and arguing that it was not your fault worth the cost savings of your repair vs replacement?We add emergency lights to the parts bin when the unit fails and just change it for the 15$ it costs.