TideLog Archive for the “Security System Repair/Installation/Upgrade” Category

This is another wear related symptom, and often occurs on power down of an old system after a power cut. It is again to do with the input regulation circuit (the main resistor, diodes, and rectifier transistors bolted to the keypad chassis). If your Optima starts OK on battery, but not on just the mains, the cause of this is the CPU isn’t getting enough power to start up from the AC to DC rectification stage. The start sequence goes visually like this:

  1. Power is applied, the regulators get up to working voltage, and start supplying power to the CPU.
  2. The LED’s all come on, briefly, as the CPU boots up, doing its self test of itself, and the NVRAM, containing your code and exit/entry timers.
  3. Within a few milliseconds of 2 above, once the CPU has started, the LED’s go out, and the alarm now goes into a full alarm condition, leaving just the Power LED on, and any open Zone LED’s. If no zones are open, just the power LED is on.

If the LED’s all stay on with no more activity or sound, the CPU isn’t starting correctly, because the voltage to it is insufficient coming from the AC to DC rectifier stage. Allowing the alarm to start here going into full alarm, would cause too much current inrush, and voltage drop to sustain keeping itself running, due to the strobe/bell and 13v PIR’s drawing power when there isn’t enough.

The transformer puts out 16.2v AC. If the voltage at your battery charge terminals with no battery connected is less than 14v, (the last one I did was 10v) the whole system is being starved of power. The two transistors that are bolted through the keypad chassis need to be replaced, the big three-legged things top right of this picture with the holes through the tags:

Optima-XM-board-faulty-regulators

I always replace both to make sure, as they can be quite stressed out at such an old age, and be breaking down under load, as does the 47 ohm battery resistor. I also check the capacitors accompanying them. The leftmost transistor is a Toshiba TA7805S Positive Voltage Regulator which seems to be the battery regulator, I’ve uploaded the datasheet to Tidelog HERE. The second (rightmost) transistor is an ST Microelectronics LT8I5CV, for which I cannot find a datasheet, and I assume is the AC rectifier stage’s main DC regulator.

I am attempting to find suitable modern equivalents for these regulators, so if any electronics guys out there can help, I’d be most grateful, as finding info on these 15+ year old components is tricky! I’m running out of working ones to cannibalize off old unrepairable Optima boards! A good alternative to the Toshiba TA7805S is the Panasonic AN7805F, the datasheet is on TideLog, HERE, for you to take a peek at, if you understand electronics 🙂

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I recently had a TideLog reader, Steve, contact me about his Menvier TS800 control panel, saying the panel was fine, but the charge voltage was intermittent, even with a new battery. A few days afterwards he dropped it off to me, lo and behold, just like the Optima, a worn resistor, under the keypad. Here’s a picture of what it should look like, and where it is located:

Menvier-TS800-resistors-locationThe one I’ve highlighted in green, labelled R52, supplies the +ve 13.6v feed to the battery, via D14 to the bottom left of it, which also seems to supply the telephone module terminal block with +ve voltage too. R83, which is the green resistor highlighted in blue, supplies the AUX 12v for PIR’s and such, and 12.6v to the bell.

Check both resistors, and all diodes for continuity and correct resistance, use my band code chart, in the Optima article, by clicking HERE. R52 on Steve’s board wasn’t badly burnt, but the resistor ceramic coating, along with the colour bands, had come off, there was slight burn evidence at the solder joints, and the voltage was stable until the board was under load, once the resistor warms up it breaks down when loaded with a flat battery on the charge rail.

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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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The Optima XM posts on my blog have proved to be massively popular, with many people asking for help with their systems. Recently I have had a big influx of people asking if I would fix their PCB’s. I do fix them, but have a specific way of doing things to prevent your system being inactive for extended periods and a risk of burglary.

I don’t normally accept boards for straight repair-while-you-wait services due to waiting times depending on chips needed, like the CPU as they need to be ordered and imported specially. Then I need to solder the components and soak test (not in water! See link to Wikipedia article!) the repaired board under full simulated load with PIR’s, siren etc in my test lab for 72 hours. This leaves you vulnerable as your alarm is inoperative.

My procedure is a part exchange service, one of my repaired working boards exchanged for your non-working board, and part cash, that way you’re less at risk as it takes much less time for your system to be running again. My cost is £15 cash and your old board, the money covers postage via Recorded Next Day or courier of my working board. Funds can be transferred via PayPal or bank transfer for security.

The working board will be factory reset so make sure you make a record of your old board’s arm/disarm code and delay times. I will program the new board for you with those settings if you so wish before sending it to you. Your old board is then repaired in my spare time, reset to factory settings and used in the exchange cycle all over again. Recycling is really cool 😉

 

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I’m seeing a massive trend on the Internet, and I don’t like it. People are taking free service manuals available on the internet, collecting them, and then selling them on. I feel this is illegal, because:

  1. They don’t own the copyright to the service literature.
  2. They don’t have the rights, nor permission to SELL for profit, or a license from manufacturers.
  3. They often charge extortionate prices!

All for stuff that isn’t theirs! Tradebit, eBay, and all the other sites that charge on a per-manual basis, I don’t agree with, and detest them hugely. Add to that they often slap their own watermarks on, secure the documents with passwords (tampering with stolen goods) so that no-one can edit them. Service manuals are only public because they’re ILLEGALLY LEAKED, so all these arseholes are committing a criminal offence, by selling stuff that isn’t theirs.

Sites that offer unlimited downloads for a tiny monthly fee I agree with, as these aren’t extortionate, and they host the files on a server they pay for, so you’re not actually paying for the material, just the right to access the website. The ones I use even have permission, and pay royalties to manufacturers.

So, eBay sellers like “servicemanualseu”, and all those Tradebit cowboys selling a single 3 – 30MB file for $19.99, AVOID them. I often find that a quick Google reveals the stuff is available free elsewhere anyway. I’ve reported people like these to manufacturers, and a few have actually been disciplined, good riddance to ’em and all! These cowboys’ excuse is “we charge so much to stop DIY’ers”, but it isn’t your place or right of decision to say who can have them and not.

I have links with people in the electrical repair industry, being a qualified technician. I pay far less for a bunch of manuals from a manufacturer that wouldn’t even buy me a Tradebit cowboy’s single manual!

 

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