soarertvtunerrepairmanual

Figure 1

Press and hold the two buttons as shown on Figure 1.

Figure 2

Turn the ignition key to ACC, then to ON, ACC, ON, ACC, ON and ACC. Hold at each step for around a second.

Figure 3

The car diagnostics screen will appear as shown on Figure 3. Touch the button circled in yellow.

Figure 4

The screen on Figure 4 will appear. This screen will stay for a few minutes until the car diagnostics has finished.

Figure 5

Next the diagnostics results screen will be displayed. Note the yellow circle on Figure 5 show that the TV tuner test has passed successfully.

Figure 6

If the TV tuner test shows a digit, this is an indication of a fault. Figure 6 shows TV tuner error 12 – TV tuner power supply test failed.

Dismounting the TV tuner

For a step by step explanation on how to dismount the TV tuner from the car please see Soarer TV conversion with two audio/video inputs.

Figure 7

Figure 7 shows the TV tuner insides after the top cover has been removed. There are two PCB boards. The top one is the TV tuner power supply board. The bottom one is the main TV tuner receiver board.

TV Tuner error 12 repair

If the tuner test described above shows error 12, that means there is a fault in the DC to DC converter located on the top power supply board shown on Figure 8. This DC to DC converter generates +5V power rail for the tuner analog circuits and +30V power rail for the tuner tuning voltage. Note that the TV conversion kit (used for conversion in Australia, UK, Ireland and NZ) is not at all affected by this fault because it uses the digital +5V power rail.

Figure 8

The fault in all cases so far has been found to be in the transformer circled in yellow on Figure 8. What is causing the transformer failure is still unknown. For this reason, repairing the transformer only, does not guarantee that the failure will not occur again. The cause of the failure makes the +5V supply to start rising up. Once it goes above 6.8V a zener diode on the main receiver board blows and shorts the +5V power supply. The last event damages the transformer. A DC to DC converter with a damaged transformer tends to supply +12V instead of +5V. The final result is that both tuner boards are damaged. If a good power supply board is connected to the faulty main receiver board, it will be damaged (the transformer will blow up), because of the shorted +5V power rail. If a faulty power supply board is connected to a good receiver board, it will damage the receiver board because +12V will be supplied on the +5V power rail and this will blow the 6.8V zener.

The fix described below suggests replacing the whole DC to DC converter. The steps are:

-         Dismounting the failed transformer.

-         Installing +5V regulator chip.

-         Installing +30V (off the shelf) DC to DC converter.

-         Removing the faulty 6.8V zener off the main tuner receiver board.

Dismounting the failed transformer

The transformer needs to be dismounted to prevent any interference with the new DC to DC converter. First clean the transformer pins from the enamel and remove as much solder as possible with a solder wick.

Figure 9

Next heat the pins area with a heat gun and extract the transformer as shown on Figure 9.

Figure 10

Figure 10 shows the solder side of the power supply board after the transformer has been dismounted.

Figure 11

Figure 11 gives a closer view of the transformer pads and colour-marks the ones that will be connected with corresponding wire colours as shown later.

-         red pad +30V

-         yellow pad +5V

-         orange pad ground GND

Installing +5V regulator chip.

A voltage regulator 7805 will be used as a replacement of the original +5V DC to DC converter. It can be purchased from Jaycar Electronics for $1.20 – part number ZV-1505.

Figure 12

Figure 12 shows how the regulator is assembled on the heat sink at the back of one of the existing transistors K737.

Figure 13

Figure 13 shows the connection of the three wires on the other side of the heat sink.

Figure 14

Figure 14 gives a closer view of the connections

-         blue wire +12V

-         green wire ground

-         yellow wire +5V

Installing +30V (off the shelf) DC to DC converter

A suitable low noise +30V DC to DC converter is MAX5026EVKIT, a pre-assembled evaluation kit from Maxim. The data sheet can be downloaded from here:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3227

In Australia the kit can be ordered from Arrow Electronics for $47.48.

Figure 15

Figure 15 shows the component side of the board. The connectors circled in yellow need to be removed or cut to decrease the thickness of the board.

Figure 16

Figure 16 shows the solder side of the board. The pin circled in yellow needs to be removed or cut to decrease the thickness of the board.

Figure 17

Next do a solder join between the two pins circled in yellow on Figure 17.

Figure 18

Cover the solder side of the board with isolation tape as shown on Figure 18.

Figure 19

Attach four double-sided sticky pads on top of the solder side as shown on Figure 19.

Figure 20

Stick the kit board over the solder side of the tuner power supply board as shown on Figure 20. The yellow circles highlight four pins that could be used as a guide on where to locate the kit board.

Figure 21

Solder four wires as shown on Figure 21:

-         Black wire is ground.

-         Brown wire is +9V.

-         Red wire is +30V.

-         Orange wire is ground.

Figure 22

Cover the kit board and the wires with isolation tape as shown on Figure 22.

Removing faulty 6.8V zener off the main tuner receiver board

Figure 23

Remove the cover from the solder side of the main tuner board as shown on Figure 23.

Figure 24

Dismount the zener diode circled in Figure 24. Put the cover back and assemble the tuner.

Now the tuner should operate as per normal and the tuner diagnostics test should pass with OK.