TideLog Posts Tagged “schematic”

I repaired a Luxor LUX-19-822-COB 19″ TV/DVD Combi unit for Greg’s aunt and uncle recently. It is a Vestel, and uses both a 17IPS16-4 combined PSU/Inverter unit and a 17MB46 mainboard. According to Greg, and his aunt & uncle, there was no sound or picture. It turned out there was sound and picture, but no backlight. Inserting a DVD made the TV start the DVD software, and the DVD began playing. There was sound and a faint picture on the screen. All voltages coming out of the PPSU section were present and stable, the TV was running quite happily, albeit with no backlight.

So the power supply was sitting in standby, all main voltages off. Pressing the Power button was bringing the PSU into full On mode, and the voltages were nice and stable, as they should be. This proved the TV’s MCU was interpreting the ON signal and pulling the PS_ON pin high, and the PSU was starting correctly. The DVD module would have shown if there was any failure on the voltage lines as it wouldn’t have accepted the disc, and would have been sluggish or appear dead. The TV wouldn’t have even booted to the DVD Software if the drive wouldn’t start, which I believe is stored on the DVD drive’s Micron EEPROM on these drives, it isn’t part of the TV mainboard.

Vestel-17IPS16-4-PSU

I connected two laptop backlights to it, they flickered then went out, there was no “2 seconds to black” symptom, or red tinge, it was a “blink-and-you’ll-miss-it” scenario. Connecting the TV’s screen lamps up to a laptop inverter revealed they were fine, with no ignition lag or red/pink tinge, so my diagnosis had narrowed the fault down to the Inverter/PPSU unit. Due to not having my oscilloscope or capacitor tester handy, I ordered a new PSU/inverter board, which will be fitted soon. I don’t know what the actual fault is with the original supply, but I will be repairing and re-using it. I’ll update this post when I do repair it. Here’s the TV with the cover removed, you can see how it all fits together:

Luxor LUX-19-822-COB-cover-removed

Another PSU/inverter combi unit that made life easier for me, due to it not doing the protection shutdown feature of separate inverters, where the inverter sends a signal to the TV’s MCU that it has a fault, this then causes the MCU to either not start the TV fully to software boot stage, or to shut down into protection mode if started. Combi PSU/Inverter units do make diagnostics easier, as the TV still starts if the inverter, well, doesn’t 🙂 If the whole TV doesn’t start, the PSU section needs to be looked at, you might have flaky fluctuating voltages coming out of PL804, the L shaped section of pins that connect to the mainboard. Here’s an image I made showing the pinouts of the 17IPS16 connector, the mainboard connector, and the DVD module connector, click it to view it full size:

Vestel17IPS16 PSU Voltage schematics pinoutPlease note, this is my image, I created it using a schematics drawing program, so please don’t distribute it. If you reference it on a forum, please link to it, don’t copy it or modify it.

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Description:

This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC’s and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a “system armed” indicator.The system is armed and disarmed with a basic keyswitch. This can be modified to use a keypad, but further circuit and microprocessor additions are required. This circuit is the basis of one of the most popular alarm systems I work on, the ADE Optima & Optima XM, which was later sold as the G3/G4 in a smaller form factor case. The Optima range was available in keyswitch and keypad operated versions.

The schematic is as follows:

5 Zone Alarm System

Circuit Notes:

Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Suitable switches can be bought from alarm shops and concealed in door frames, or window ledges. You can also use PIR (Passive Infra Red) detectors, these must be on the Immediate zones.

Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 – 5 are immediate zones, which will trigger the alarm with no delay. Some RF immunity is provided for long wiring runs by the input capacitors, C1-C5. C7 and R14 also form a transient suppresser. The key switch acts as the Set/Unset and Reset switch. For good security this should be the metal type with a key.

Operation:

At switch on, C6 will charge via R11, this acts as the exit delay and is set to around 30 seconds. This can be altered by varying either C6 or R11. Once the timing period has elapsed, LED6 will light, meaning the system is armed. LED6 may be mounted externally (at the bell box for example) and provides visual indication that the system has set. Once set any contact that opens will trigger the alarm, including Zone 1. To prevent triggering the alarm on entry to the building, the concealed re-entry switch must be operated. This will discharge C6 and start the entry timer. The re-entry switch could be a concealed reed switch, located anywhere in a door frame, but invisible to the eye. The panic switch, when pressed, will trigger the alarm when set. Relay contacts RLA1 provide the latch, RLA2 operate the siren or buzzer.

The panic button circuit can have as many buttons as you want connected. It is best to ensure that the system uses no more than 1A on an alarm condition (full load state) if strobes are used.

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