Alarm Siren issue

[slybunda]

Apologies if this is in the wrong section but being a car alarm siren that makes noise i thought it be best to put it in the audio section.
Had weird alarm issues where siren made a strange noise: https://www.youtube.com/watch?v=ZjsqndhionU
took siren out of the car and checked it out and pics attached seem to be the source of the issue.
shockingly the alarm still makes its normal sound if i trigger it manually so speaker seems to be intact.
getting a replacement is gonna be next to impossible, its a Toad Ai606 which is no longer in production and cant see to find a replacement siren on ebay etc.

i suspect the battery leaked out and either the mosfets tried to keep charging the battery and burnt out or the battery acid shorted some stuff out.
is this gonna be fixable? im gonna run it without the battery so im guessing some parts of the circuit may not be needed if they are dedicated to battery charging?
iv put this up on few other forums for as much assistance as i can get. car is 28 years old and this alarm was fitted in 2002. surprisingly the caps look good. lol.

[petehall347]

they aren't mosfets but bjt tip32c , those are common and easily found . clean it up and see whats left

[slybunda]

would these be the same: https://uk.rs-online.com/web/p/bipol...s/4859777?gb=s ??

also what would these be used for? could they be audio amplifiers in this circuit?

[petehall347]

would these be the same: https://uk.rs-online.com/web/p/bipol...s/4859777?gb=s ??

also what would these be used for? could they be audio amplifiers in this circuit?

yes they work for audio

[slybunda]

I see, so im guessing the 2 that are not burnt out handle the alarm sound when it is triggered (which still works) and the 2 burnt ones handle the chirp noise when arming and disarming which no longer makes sound any more.
could this be it?

[petehall347]

no they may be part of the amplifier , also could be used in power supply . where does the speaker part plugs in ? and where does the battery plug in ?

[redwire]

The four power transistors make an H-bridge to drive the speaker. The IC generates the tones.
It looks like the battery leaking caused the bridge to kill itself along with the horn driver possibly. A lot of corrosion around the battery. Since when are NiCd's needed for a siren?
The board is badly burned, I don't see it worth repairing.
cross-posted https://www.eevblog.com/forum/chat/c...rm-siren-issue

[slybunda]

no they may be part of the amplifier , also could be used in power supply . where does the speaker part plugs in ? and where does the battery plug in ?

speaker plugs into the connector next to the transistors battery plugs in on the connector next to the aluminium capacitors, can see the wire had to be cut for the battery the connector is corroded. battery had red and black wire, speaker had black and black with white stripe wire.

[slybunda]

The four power transistors make an H-bridge to drive the speaker. The IC generates the tones.
It looks like the battery leaking caused the bridge to kill itself along with the horn driver possibly. A lot of corrosion around the battery. Since when are NiCd's needed for a siren?
The board is badly burned, I don't see it worth repairing.
cross-posted https://www.eevblog.com/forum/chat/c...rm-siren-issue

too hard to get a replacement item these were aftermarket alarm systems and production stopped many years ago. iv posted this on many other forums, car forums and electronics to get as much help as i can.
the speaker in the alarm unit still works the car can make its alarm noise like normal when ultrasonics or door switch is triggered. but the harming and disarming of the alarm doesnt make any sounds from the siren like it used to do, it just makes that constant noise here: https://www.youtube.com/watch?v=ZjsqndhionU
thats why the siren gets warm and is draining the car battery too.
so this should mean that the speaker itself is working fine still.
will get some components desoldered today and see whats left to work with.

[slybunda]

more pics after desoldering stuff, zener diode is toast its broke in half so not sure what to do there. the 2 burnt out resistors seem to both have the same resistance of 100ohm so maybe they are 100 ohm or they both got cooked to the same temp to give same wrong reading? not sure there. some trace damage too looks like a single layer board so not sure now.

[CapLeaker]

problem you have here is that massive amount of burnt carbon which is conductive and needs to be fully removed and leaves you a huge hole in the PCB.

[petehall347]

https://www.toadalarm.com/product/toad-ai606/

https://www.caraudio4less.co.uk/shopping_cart.html?zenid=30hbv53uecildcgphvea7inl93

[redwire]

problem you have here is that massive amount of burnt carbon which is conductive and needs to be fully removed and leaves you a huge hole in the PCB.

You have to wonder if this siren is properly fused- obviously not. Toad Alarm should be liable for damages and the fire hazard. I'd push for a free replacement siren... get them to recall their unsafe product.

[CapLeaker]

You have to wonder if this siren is properly fused- obviously not. Toad Alarm should be liable for damages and the fire hazard. I'd push for a free replacement siren... get them to recall their unsafe product.

I think the problem started with the leaking batteries and it progressed from there. But I agree... I would show that fuck up to the manufacturer too.

[slybunda]

Spoke to someone from toad any they not taking any liability saying the alarm should be serviced every year at a cost of £100 which is stupid since over the 20 years iv had it that would be £2000 wasted on alarm service lol.
they offered a siren replacement at a cost of £130 plus delivery which is a total ripoff.
I need to work out what circuitry is for battery charging and what part is for the actual siren operation. May be able to then reverse engineer something onto a breadboard and if it works move it to a perf board or even have jlcpcb etc make a replica.
If i had photos of a working siren with no damage im sure i could do this.
Will have to hit up all the scrapyards i know to see if i can find something.
According to another car alarm fitting company that siren for the toad is not totally unique since they said a sigma or scorpion alarm siren is compatible with the ai606.

[redwire]

I'd confirm Toad's operating instructions- as if there is a mandatory maintenance clause that would hold up in court. Every Toad battery pack is going to leak, you aren't the only person with this happening.

Toad just went to an OEM of car alarms in Asia for the product. Green custom plastic for the horn. Looks same as many others. "Vb" logo would tell more could be Viper. What a UK scam to outsource a cheap car alarm and charge a fortune for it.

What is the wiring to the siren? How many wires? It might simply have the bonnet switch combined in the wiring harness but otherwise is a generic siren.

IMHO the PC board is too burnt up to repair so I would source a replacement or connect an external siren. Look at cheap "SIR1TBB01".
You could draw a siren schematic if you really want to replicate it but the custom IC DIP-8 MCU not known if it lived through the roasting, it drives those transistors. Attached is a generic schematic of your burnt up H-bridge section to help. PCB number Vb 160-2758590

I did see the same eBay replacement battery packs 6 NiMH cells making 7.2V 250mAh for the Toad A101CL and Ai606, Laserline 670, Scorpion SA30, SA35 and Sigma S30, S32, S34. What do their sirens look like?

First time I've seen an alarm sensor for catalytic converters that Toad offer, I wonder how it works one wire only must be a steady ground unless the O₂ sensor or cat bolts being removed.... but they just saw them off here.
Ain't nobody got time to unbolt anything lol.

[slybunda]

thanks for that info above. iv got someone sending me a siren from a cobra alarm so will see how that is inside.
the siren has a single cable which has 3 wires in it that go to it from the control box. the 3 wires are Ground, Trigger and Vbat, so im guessing its just 12v + and - along with a signal to trigger the siren.
im wondering if the zener diode that broke off was for the battery, is it possible it is forward biased when it has above something like 9v and then reversed bias when the car battery voltage drops too low to power and trigger the siren?

[redwire]

Only 3-pins then any generic siren could work, just some have (+) trigger others have (-) trigger. I don't know if the siren sounds when unplugged as a tamper alarm? TRIG is normally pulled high at the MCU.
It looks like a crappy constant charging circuit, add that to the Toad lawsuit.
Z1, Q1 are possibly for the switchover to battery power. But you don't want false chirps when trying to start the car batt voltage drops so there must be no tamper detect for power disconnect.
Or the zener Z1 is for charging. Not sure without pic of the top area there.

[slybunda]

pic of the top added here. missing zener is marked Z1 on the board.
my siren had a nickel cadmium battery, later revisions seems to have switched over to nimh battery.

im sure the siren used to sound when battery was removed from car if alarm was armed i think. cant remember that far back and this battery seems to have been dead for a long time.

[slybunda]

removed the sticker of the small chip and its got some markings on it:

12C508A
04/P01V
0113

maybe if i can find a datasheet for this it may give schematic info of whats supposed to be connected to it and how?