Dashboard Clock goes off?

[sven337]

OK, this is fixed! Hopefully this time for good.

I had an adjustable MP1584EN-based buck module ("D-Sun" chinese brand).
These super common modules you can find for a few dollars.
For example:
https://www.ebay.fr/itm/Ultra-Small-...-/322408214136

I used my poor man's lab power supply to test what were the minimal voltage and currents needed to obtain full brightness, and I found out that a constant voltage 1.5V supply would yield a steady 300mA current that would correspond to full brightness. Going to 2.5V would increase current to 450mA without any visible change in brightness, and starting at 4V the filaments would glow red.
(Sorry about the quality of my pictures, I was focused on solving the problem and only took the pics as an afterthought).
https://perso.aquilenet.fr/~sven337/...test_setup.jpg
https://perso.aquilenet.fr/~sven337/...k/halfwatt.jpg
https://perso.aquilenet.fr/~sven337/.../2halfvolt.jpg

Once this was proven working, I cleared some space on the board by removing the transistors and their base and emitter resistors.

https://perso.aquilenet.fr/~sven337/...cleanboard.jpg

Laid out a layer of tape to insulate, soldered the module and taped it in place. This fits with room to spare when reassembling everything.
https://perso.aquilenet.fr/~sven337/...lock/final.jpg

Sorry that final picture is so anti-climactic.. Everything works quite well for now. I hope it lasts, this time, but see no reason why it wouldn't.

[Kaanktm]

Originally Posted by sven337

OK, this is fixed! Hopefully this time for good.

I had an adjustable MP1584EN-based buck module ("D-Sun" chinese brand).
These super common modules you can find for a few dollars.
For example:
https://www.ebay.fr/itm/Ultra-Small-...-/322408214136

I used my poor man's lab power supply to test what were the minimal voltage and currents needed to obtain full brightness, and I found out that a constant voltage 1.5V supply would yield a steady 300mA current that would correspond to full brightness. Going to 2.5V would increase current to 450mA without any visible change in brightness, and starting at 4V the filaments would glow red.
(Sorry about the quality of my pictures, I was focused on solving the problem and only took the pics as an afterthought).
https://perso.aquilenet.fr/~sven337/...test_setup.jpg
https://perso.aquilenet.fr/~sven337/...k/halfwatt.jpg
https://perso.aquilenet.fr/~sven337/.../2halfvolt.jpg

Once this was proven working, I cleared some space on the board by removing the transistors and their base and emitter resistors.

https://perso.aquilenet.fr/~sven337/...cleanboard.jpg

Laid out a layer of tape to insulate, soldered the module and taped it in place. This fits with room to spare when reassembling everything.
https://perso.aquilenet.fr/~sven337/...lock/final.jpg

Sorry that final picture is so anti-climactic.. Everything works quite well for now. I hope it lasts, this time, but see no reason why it wouldn't.

Hi, thank you for sharing this. It is really helpful. Hope it lasts lifelong. :)

Could you please inform about the circuit connections on the board. I’m not bad with electronics but apparently not as good as you. Also i couldn’t find about detailed module connection schematics.

So i will appreciate and be very grateful for your reply. Thanks again. This forum rocks. :)

[sven337]

Originally Posted by Kaanktm

Could you please inform about the circuit connections on the board.

Are you asking about how to connect the buck module I had to the board? Assuming you have the same, but all buck modules work the same way anyway, you have three leads to connect: Vin, Vout, and GND.
If you look at my very blurry (sorry..) last picture, you can see two red wires and one black wire (at the bottom)*come out of the module. The black wire is GND, and I've taken it at the GND of the capacitor that is next to the blue inductor.
Vin was the + of this capacitor (I think the capacitor/inductor/diode here are an input filter, all I really care about is that there's a constant 12V power supply available there and it was the input of the NPN transistors).
Vout is the leftmost pin of the VFD connector (all 4 left pins are connected together).
I hope this helps you

[Kaanktm]

Originally Posted by sven337

Are you asking about how to connect the buck module I had to the board? Assuming you have the same, but all buck modules work the same way anyway, you have three leads to connect: Vin, Vout, and GND.
If you look at my very blurry (sorry..) last picture, you can see two red wires and one black wire (at the bottom)*come out of the module. The black wire is GND, and I've taken it at the GND of the capacitor that is next to the blue inductor.
Vin was the + of this capacitor (I think the capacitor/inductor/diode here are an input filter, all I really care about is that there's a constant 12V power supply available there and it was the input of the NPN transistors).
Vout is the leftmost pin of the VFD connector (all 4 left pins are connected together).
I hope this helps you

Actually i was quite able to clear up my mind after asking the question. With your answer it is now crystal clear. Thank you so much again. Hope it would last long.