Tell me, it still works on your car? I saw brownish color on the board behind transistors, resoldered them but asumed that won't work... This is an easy fix if works... So you said it's first and the last pin where you connect the step down? I see there is no - wire on last picture... where did you solder that pin?
Yes, the fix still works for me. Just resoldering them won't last. The step down module's input is connected anywhere you can find 12V, on the capacitor is a good point, very visible on the picture. The output goes to the first pin on the very left of the VFD connector. The output minus doesn't matter: this is a non-isolated buck, it is already connected to ground through the input pin's ground. So yes I only connect three wires.
Does that make sense?
I'm just testing the vfd module now... Connected it to 1.5v and 0.3A without any other power source... Shoud I attach power to complete motherboard or should it work without supplying power to the motherboard? If yes, what voltage should I give it? Because seem that vfd module is dead...
The VFD module is a passive device. You supply power to the filaments to heat them up, that is what the 1.5V thing is about. That is what is broken on the board.
It will not display anything until connected to the controller, so you need to power the motherboard. The motherboard takes 12V and my first picture shows the correct contact points. It's really easy ;)
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Hi Sven,
I did as per you instructions and orange lines appeared VFD. Tried to change voltage on buck module but then numbers are unreadable. Any ideas why?
I have the same issue. On my workbench I replace the 6 transistors. Some data: - power supply - 14.6 V - voltage C-E 11.3V - current 0.042A per transistor, total 0.25A for heating of VFD. - approx 0.46 W dissipation power per transistor.
I decide to cut a cooper heatsink for the 6 transistors and solder it to the tab of each one.
It's been a long time you shared that fix and it remains up-to-date, I did it today. Thank You ! I removed transistors & resistors all around the burnt area (didn't even try to fix them), soldered and insulated the buck module found on a famous chinese online shop, and there you go ! It worked right away and I can tell, as a bonus, that dashboard light dimming when I switch headlights on, still works. It took more or less one hour to carefully complete that job. One again thank you Sven !
It's been a long time you shared that fix and it remains up-to-date, I did it today. Thank You ! I removed transistors & resistors all around the burnt area (didn't even try to fix them), soldered and insulated the buck module found on a famous chinese online shop, and there you go ! It worked right away and I can tell, as a bonus, that dashboard light dimming when I switch headlights on, still works. It took more or less one hour to carefully complete that job. One again thank you Sven !
Perfect and easy fix.
Most of the work is taking the unit apart :-)
I left the broken parts on the print.
For the fixers: buy a buck module, connect it to a power source (12v) and adjust it to 1.5v BEFORE you connect it to the clock module otherwise yo might destroy the clock module cause of high voltage.
Succes !
Sven, thanks for sharing this !
Thank you, Sven!
A few notes:
- nominal filament power supply is 1V, and it varies a bit with main power supply fluctuations (but less then +/- 0.1V)
- it's good to remove at least these six 22 Ohm resistors from the PCB
- VFD dimming is done by PWM on segments (or grids) supply voltage, not by filament voltage adjusting
- there is a voltage drop of around 0.2V on PCB trace between leftmost transistor and VFD connector - I noticed that as I connected buck converter output to that transistor's collector.
- I replaced buck module's variable resistor with two resistors of calculated value
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