Oct 16

While attending the 2017 edition of Mini Maker Faire at Aarhus central library (DOKK1) We (Labitat expedition) also went to the obligatory visit at OSAA (Open space Aarhus) and looted some stuff from their Limbo-shelves.

In between all the good stuff there, I found a Sony BDP-S360 BluRay-player. It went back home for exploring.

Upon powering-up it just sits there saying “Wait” on the VFD while making some mechanical noises.

As i have no interest in having a BD-player it was turned into parts. Nothing really useful was found inside. Bog-standard primary SMPS, 22 watts max output and mainboard with more or less single-chip-solution.

The mechanics had the old venerable KES-410-optical pickup (known from the ‘PS3 fat

As i have a special interest in VFD’s (Vacuum Fluorescent Displays) (amongst other older display technologies) i took a closer look.

BDP-S360 VFD Front panel

It has all the power supply circuitry onboard directly – usually the Filament-drive and VEE-supply is built-in in the main SMPS, but Sony apparently went for the simpler approach here. I like that!

2 minutes on Google yielded the service manual with nice schematics and pictures of the front panel-board foil and silkscreen.

Looking at the schematics for the power supply for the VFD it’s pretty bog standard-kinda-deal here.

Transformers have always been an interesting item – for most a “black box”. I would like to know the number of windings etc. so i took out the transformer, put it into Acetone for a minute and opened the core (the outer ring lifts off, revealing the windings)

BDP-S360 VFD Transformer pinout

BDP-S360 VFD Transformer opened up BDP-S360 VFD Transformer bottom view

I documented my findings here, in case that it might come in handy for someone else hacking with VF-Displays


Circular core, 10 pins.
Primary, pins 2,3,4
Feedback, pins 5,6
Secondary, VEE 1,10
Secondary, Filament 7,8,9
Tested at 160kHz
Primary inductance (end-to-end)    70 uH
Feedback inductance 2.2nH
Secondary, VEE 140uH
Secondary, filament 3uH
Winding order:
15+15 Windings 2-3-4 0.1mm
3+3 Windings 7-8-9 0.1mm
44 Windings, 10-1 0.1mm
5 Windings, 5-6 0.1mm
Voltages measured:
VEE is -18V
Filament supply is 5.4Vpp running on a -13.7V bias
Switching circuit runs at 216 KHz
The VFD-glass itself seems to be custom-part with special symbols for BD-player. I couldn’t find anything online on it.
The controller on board is the old and venerable PT6315. It uses a 3-wire interface and is very easy to interface with.
I will keep the board and parts for some more fun another day.
For kicks i tried making my own transformer on a EP-7 core with PC40-material.
Same number of turns, 0.1mm airgap (2 layers of Kapton tape)
Slightly higher output voltages, same switching frequency.
Jul 27


The newest addition to my swarm of never ending pile of interesting electronics is the Arduino Yún.

As I was getting some parts from Newark Canada, I just thought, well i’ll get myself an Yún to play with as well.

Yún means Cloud in Mandarin, so it’s quite obvious it is an Arduino meant to be connected to the cloud (Internet of Things).


As I usually do, I hack into the deeper workings of devices, and in the case of the Yún, there will be no difference.


I will dig deeper into it’s internals – have You ever seen the “Black magic” hiding under the shield? I haven’t.

Also, later I will look into how much power this unit takes, and to see if there is any way to tweak the power usage.



Setting up the Yún was a breeeze – I followed the instructions over at http://arduino.cc/en/Guide/ArduinoYun

Quickly I had it connected to my own WiFi-network, and programming it over Wifi with Arduino 1.5.7 (Beta at the moment) worked quite nicely.


Well, let’s get to the point, what exactly is hiding under that EMI-shield?

A quick desolder job with the Solder-wick (Chemtronics 10-100L, the best money can buy!) and the cover was off.

Yun uncovered - overview

Yun uncovered – overview


Aha! – three chips – that ain’t much.

On the left we have a Winbond W9751G6KB-25 – 16 Bit DDR2-RAM – this is the main memory for the DD-WRT linux-environment that the Yún runs.

In the center there is the Atheros  AR9331-AL1A Wireless SOC – This is where all the magic happens.

And on the Right, once again from Winbond, a 25Q128FVSG – a 128 MegaBit Boot-flash, using SPI-interface.


So, now you know what hides under the shield, and you do not need to void the Warranty on your Yún to find out 😀

– Due to time constraints, I will leave the power-measurements to the next blog-post, as I need some time to gather readings, and present them in a usable manner.