TideLog Archive for September, 2012

This happened to me recently, while I was updating a few Cydia apps. After respringing, all my app store app icons were missing, but using iFile I could see the apps themselves were still installed to usr/mobile/applications.

No amount of respringing, rebooting or complete powering off brought them back and I couldn’t launch them via Terminal. I even tried using the Cydia app Poof! to turn the icons off, respring, then back on again, but nothing worked. What did work though was reinstalling one of my missing apps after backing it up and deleting it, all of a sudden the icon tiles came back, then after a reboot they had their icon pictures again!

Another weird “feature” of a jailbroken Apple toy!

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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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We all know that PC World are clueless when it really comes down to computer repairs. Charging £40 just to reinstall a driver, or as in the Sky News investigation, £229 just to reseat a memory stick, which should be a 10 second no charge job. When it comes down to their KnowHow scam, it gets worse. They used to be called TechGuys until they got so much bad publicity they had to rebrand and rename.

Here’s the truth about them. They get their staff from an agency called ADECCO. The people they take on have little or no electronics background, and only have about 6 months training with Adecco themselves before being taken on by PC World into their KnowHow scam, and are allowed to roam free on people’s televisions, washing machines and whatnot, with a multimeter that they don’t even really know how to use.

Their staff will come out, for example to fix a washing machine, and NOT know how to fix it (So they should now be called NOT KNOWHOW!!). I once set a TechGuys engineer up by putting faulty bearings in the tub drum of my washing machine, and calling them out. He went through a ton of basic checks, like checking hoses, the motor, and did a basic PAT continuity check, which failed (I know his test was wrong, because I professionally fix washing machines, and fix my own). After an hour he still couldn’t figure it out, after several calls to head office he decided to poke around a bit, then tell me the control PCB had gone, just to get a problem out in the air so he could have the £60 callout and diagnostic fee.

As soon as I came clean about what I’d done, and showed him my NIC-EIC electrical certificate, he soon got the finger when he still asked for £30 callout. He couldn’t get out the door fast enough he was so embarrassed, so fast in fact he left his multimeter behind. Lo and behold the battery LED was flashing, so his multimeter was giving false readings due to lack of power.

They always say a bad workman blames his tools, but in his case both he and his multimeter were wrong, poorly configured and short of power. Avoid the whole of DSG (Dixons Stores Group, including Currys, PC World and Dixons, plus PixMania) like the plague. Their latest KnowHow ads saying they’ll show you how all these new HD 3D TV’s work is just a cover, they don’t even know what 3D or HD even are!! They charge £100 to fit a flatscreen TV bracket, the cost DOESN’T even INCLUDE the bracket! In Kitamura Computers we fit and supply a HIGH QUALITY bracket for as little as £50!!

In my research of Adecco and KnowHow staff, I found out that everything KnowHow do revolves around output quantity, and nothing else, which really I already guessed. Things that are said to the general public might appear this is not so but don’t be fooled. Just go on the web and see their past history. Adecco staff I contacted on the web (remaining anonymous) constantly feared for their jobs if they didn’t meet these quantity targets, and they felt like Big Brother was watching their every move.

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