This is one of the most common Optima XM problems I’m fixing now that most of them are over 20 years old. Take a normal Optima XM board, and at first you wouldn’t visually think there’s anything wrong with it, would you?

It visibly looks fine, but your system is still exhibiting weird symptoms. Do you have any of these symptoms on your system?

  • Power light on, but no other sound, keypad locks out?
  • System works apart from sounder or strobe/PIR’s?
  • Appears to work, makes all the right noises but won’t accept any codes?
  • External siren makes weird humming/buzzing noises along with internal siren when wired together?

First if you do get symptoms you should check all zone and tamper wiring/switches, as it’s a big misunderstood issue here on TideLog. Then you should check the transformer for continuity, and around 17 to 18v AC on its output. Once you’ve checked all that and are still scratching your head, undo the screws and bolts holding the keypad chassis to the board, suddenly you see the problem area:

The area I’ve labelled 1. contains the main voltage regulators. They take the incoming voltage from the transformer, smooth it out, then pass it on to the rectifiers in Step 2. above them, these convert the AC into DC, smoothing it out even more to make sure the power isn’t dirty, or has spikes in it, with help from the big capacitor to soak voltage up. From there it is then distributed to all the sections of the board, being split into all the different voltages for the board’s computer, EEPROM memory (where your code, entry/exit delay times and bell on time are stored), and timer chip, and the terminals for all the zones, tampers, strobe, bell etc.

Those rectifiers get hot, the big three legged things in Step 2 that had the keypad chassis bolted through them, the keypad chassis acts as a heatsink to help dissipate heat. Slight signs of burning and blackening on the plastic panel casing around those are perfectly normal, the rectifiers tend to burn off any dust that lands on them. NOTE: When reassembling, the rectifiers MUST be bolted back through the keypad chassis, if they are not dissipating to a heatsink type device firmly fastened they can burn out pretty quickly. The rectifiers go over the top of the keypad chassis lip, the screws go through this and bolt on to the back. Thermal compound isn’t necessary on these.

When used in switchmode power supplies (SMPS) you’ll see them bolted to thick heatsinks with thermal material between them. They are often used in Plasma TV’s they are in droves inside those as they contain several power supplies!

The most comon reasons for the system to fail are:

  • Defective transformer. If there’s too many surges or spikes, over the average 20 year lifetime of most of these Optimas, they take a hell of a beating, the two sections of the regulation circuit take the brunt. The transformer is wired straight to the mains, with no spike/surge circuitry built in, only a fuse.
  • Wear. When semiconductors and resistors wear out they sometimes (not always) short out, stressing the rest of the circuitry out.
  • Defective battery. As mentioned before both the transformer and battery are wired to the regulators so any damaged shorting battery will cause stress, as well as a fault in the battery charging system, also handled by the rectifiers. The battery fuse (the two fuses near the AC and BATT terminals are the Bell & Battery fuses) doesn’t always blow for some reason. I’ve deliberately shorted one out, the battery caught fire (I was in a controlled environment) but still the fuse didn’t blow!

A short on the terminals themselves won’t normally cause damage, as they have a line of resistors and solid state relays along the top of the terminal blocks. Some early versions of Optima boards don’t have relays, the one in my picture doesn’t, but I have boards for repair that do. The terminals to the right have rectifiers as they are voltage rails, for the Strobe, Bell, and 13v rails for the PIR power.

If you have a strange symptom, get in touch and I’ll help 🙂 Just make sure you’ve already checked zone and tamper wiring 🙂 And don’t forget, the transformer output wires to the board are not polarized, but the battery ones are!

The fix to this problem isn’t just replacing the burnt resistor. I always check the diode banks on either side for continuity as the resistor often shorts them, resulting in them all needing replacement. If they’re not checked damage to the battery (overheating, fire or explosion) may result as those diodes control the charging system. An overvolted or overcurrented battery can explode violently like a shorted capacitor!

I can fix this issue for you, get in touch. I normally charge around £20 for the components, soldering, testing plus return postage. I set the repaired system up on my test bench and full load stress it for 72 hours complete with battery.

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118 Responses to “ADE Optima XM Alarm – Burnt Regulators”
  1. justin moorhouse says:

    hi,i have optima xm6 & the alarm is going off all the time & i cant reset or do anything,the keypad works but i cant switch so i just keep disconnecting the mains cable,any help would be great.thank you

  2. justin moorhouse says:

    hi,i have been haveing a few problems with mine xm6 alarm keeps sounding the alarm off all the time,(when i have taken the keyboard off)i can see on the circuit board that there are 2 burns marks around 2 of the resistors,can you still repair one off these circuit boars,thanks justin

  3. d field says:

    i have just had my optima xm alarm replaced after many years of good service . would you like the old alarm for free . e-mail telephone no,0208 595 4801

    • Tidosho says:

      Hello Mr/Mrs Field,

      I would be delighted to take it off your hands for refurbishment! I have emailed you with postage details. If you’d like a contribution to the postage costs, let me know 🙂

  4. Ian says:

    Hi my nan has got this panel and I have checked the battery, connections and the fuses but when set it goes off randomly in the night any ideas.

    • Tidosho says:

      Hi Ian,

      This could be either a zone wiring fault, or a resistor issue. By “it goes off randomly” do you mean just the internal speaker of the panel, or a full blown alarm?

  5. Mike says:


    I have an Optima XM alarm which I don’t actually use. Its making a weird clicking and buzzing noise outside. Can I disconnect somehow which will give me some time get the problem fixed without annoying the neighbours. Many thanks.


    • Tidosho says:

      Hi Mike,

      If you want to disable the whole alarm then you need to disconnect the battery and the mains. Turn off the mains to your panel, then remove the panel front cover, you’ll see your battery, disconnect the red and black leads from it, this will disable the whole system.

  6. Tim Richardson says:

    If the charging voltage is more than the normal 13.6v is this due to a failure of the rectifying diodes.Some of my systems give a charging voltage over 14v.

    • Tidosho says:

      Hi Tim,

      The charging voltage is actually supposed to be over 14v, normally 14.2v for a 12v battery. I made a mistake in the article as I used a faulty system as a reference. If the voltage is much too high, like 16v + It could be any one part of the input rectifier circuit. I’d check all components to be safe.

  7. anne stone says:

    Hi, I have an Optima XM and last night the alarm started buzzing for no reason and won’t stop. The alarm has not been used actively for a short while now. Putting in the code makes no difference to the noise amd when removing the front cover, there is some blackness at the top and it is warm. Have you any suggestions? Thank you.

    • Tidosho says:

      Hi Anne,

      This is a classic symptom of the regulator having failed. The blackness and warmth is actually normal as it runs warm and burns off dust, can you actually see if the resistor is damaged?

  8. Hayley summers says:


    Wonder if you can help me? Just moved into a new house and we have an optima xm alarm, we thought we were activating the alarm but when we tested the outside bell it doesn’t make any sound. The strobes and zones are fine just the outside bell doesn’t sound and the inside one does. We have changed the fuse for the bell output to no avail, any other suggestions we can try?
    Many thanks

    • Tidosho says:

      Hi Hayley,

      It is either the sounder itself has failed, or the 12v rail inside the panel has failed. Do you have a multimeter to hand, or know someone who does? On the terminal block inside the panel you’ll see terminals marked BELL with + and a – for the polarity. If the wires are inserted correctly (red for + and black for -), check the voltage here, it should be 12v. If it is, the outside bell box sounder or its wiring has failed.

      If there is no voltage here, the panel circuit board needs to be diagnosed and repaired.

  9. Manc says:

    I have a optima xm fitted around 2007 / 2008. The panel is making a buzzing noise, when I try to enter the code by pressing the buttons there is no noise plus the code is not accepted. At the time when the alarm started making the buzzing noise it was not in use. I have checked internally and cannot see any burnt areas but I did find one of the battery connections was not connected.

    I reconnected the battery connection and reinstated the alarm. The buzzing noise came back and there was no noise when I tried to enter the alarm code. The panel will not accept the alarm code.

    I have removed the battery and disconnected the power.

    Any ideas what has failed?



    • Tidosho says:

      Hi Steve,

      I removed your duplicate posts, be sure to only press submit once, I have to approve the first comments from new posters. Your next one will show straight up. The first rule in electronics is that components don’t have to look bad to be defective, they can look perfectly good, and test OK out of a circuit, but as soon as it is under load in circuit it fails. From the buzzing this is definitely your regulator and charge circuit that is dying.

      I no longer have the spare time to be accepting other people’s boards in the post for repair, so the best advice I can give is to consult an electronics engineer. Don’t ask an installer, they won’t be trained, or know what you’re on about as soon as you mention regulators!

  10. Phil says:

    Just moved and inherited a optimaxm6 and power on light showed but alarm keypad did not respond .Replaced battery and got the system up and running replacing codes through clearing nvm and all tests were positive .System worked for three days then day light went out and system failed.Suspect the battery lasted three days and was not being charged.Have you a view on my theory.

    • Tidosho says:

      Hi Phil,

      It looks like your regulator & charge circuit is worn, and breaking down under heat and load. I no longer have time to be accepting people’s boards for repair in my spare time, due to taking a second job, so the best advice I can give is try to find a circuit board repairer/electronics engineer who will do it for you. Don’t ask an alarm engineer, they normally aren’t trained in board level stuff, only basic installation.

  11. Kieran says:

    Hi Tidosho,

    i have an optima xm here and the keypad wiring has burnt out and broken over time, i need a new one but cant seem to find one, any ideas on where i can get parts or do you have one yourself with a working keypad that you would be up for selling.

    Many Thanks

  12. Andrew says:


    I have an Optima 6XM alarm which works fine until there’s a mains power cut.
    The alarm then rings and there is no power to the Keypad.
    After replacing the battery|I discovered the 1.6A battery fuse had blown
    and a new fuse blows immediately.
    Can you please help?

    Thank you


    • Tidosho says:

      Hi Andrew,

      There’s a short on the battery charge circuit, likely one of the transistors or diodes has shorted, this will keep blowing fuses until fixed. What happens if the fuse is replaced and the system powered with no battery? Does it blow again?

  13. Robin Hunter says:

    Hi, Can you help please, we set our alarm (Optima 6XM) on going away last weekend, on return the blue strobe light outside was operating, when we opened the house the alarm did not sound (there had been no attempt to enter the property). We have now found the control panel will not respond to any touch, including reset. The strobe is still flashing. The only light showing on the box is power all other lights are off including “Day”. Any ideas what could be wrong please?

    • Tidosho says:

      Hi Robin,

      Have you tried powering the system down completely, removing the battery and killing the mains? I suspect you have an electrical issue, the regulators are worn and the strobe is using all the power, hence why it doesn’t respond to anything. If you remove the cover, can you see the state of the regulator? Can you try powering it without the battery? If the battery is old and the regulator worn, the old battery may be putting too much resistance on the system.

  14. Steve says:

    I found your site whilst looking for some advice re a couple of optima alarms, had an issue with the house alarm (optima concept, remote keypad) when you turn off the power it alarmed and once powered back on had reset to default settings, checked the battery and only 8v, 9v with alarm powered, swopped battery from my garage alarm (optima XM) and now getting 13v with alarm powered, so I suspect it’s the battery, when i opened up the garage alarm I tried to test for transformer output to check the charging (intended to do a comparison with the house) but unable to get a voltage reading, reconnected everything and the garage alarm now won’t respond properly, it will accept the default code once and let you change the code then it won’t do anything, no codes work, it won’t go into engineering mode, I had to remove the cover and disconnect the battery to stop the alarm sounding, no sign of any heat/burning as per your pictures, though there was a bit showing on the house alarm panel, both alarms getting on a bit now, have you any suggestions? Thanks

  15. Al Pacino says:

    Hi I have a Optima house alarm box and the internal alarm just randomly went off with the tamper sign displayed. I entered the alarm code successfully and managed to stop this with the lights still remaining on. I noticed there seemed to be a slight burning smell around the area of the box.

    The battery was replace a few months ago do you think this could be the cause?

  16. peter storey says:

    Hi we would like you to repair the circuit board on our old Optima XM alarm system. as it as had a power surge and as now burnt like the one in your picture. Can you tell us the procedure for you to do this for us. Many Thanks

  17. Geoffrey Hudson says:

    hi I’m after a front panel for my optima xm could you please advise were to buy from please
    thank you

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