Fixing a blank LCD on a Yamaha EMP-700

The Yamaha EMP-700 is a great unit, but a common problem seems to be that the LCD display gets blank. Backlight is working but no characters are showed.

I recently bought one of these units and ran into this exact problem.

The service manual was quite easy to find on the net and I noticed that the LCD seemed to be Hitachi HD44780 compatible. So, I bought a standard LCD 2x16 characters and hooked up but it did not work, the same blank display.
Information on the internet is quite sparse about this problem, but I found a post in Spanish which I figured out indicated a problem with the contrast voltage, see schematics below. After changing the termistor/resistor voltage divider to a 2k trimpot, see image below, the leftmost marked rectangle, the hooked up display worked like a charm. This proved that the electronics controlling the main parts of the electronic circuitry worked. Changing back to the original display, it did not work, so I realized that there must be another problem. Also, there was no way to fit the hooked up standard display with its larger footprint into the crammed space of the unit. Back to the drawing board to try to solve the problem with the original display.

Another post about this problem, buried within a review on Harmony Central indicated that there might also be a problem with the capacitors connected to the LCD controller. I had noticed these capacitors, and thought that they might be the problem. Electrolytes have a tendency to fail over time and when I removed and checked them, there are three of them, all seemed to have failed. The value of these capacitors is 4u7 16V and I replaced them with compatible Tantalum capacitors. See image, the rightmost rectangle. I fired up the unit and the display worked again!

To solve this problem, first try to change the resistor/thermistor voltage divider. The only thing needed is to lift the lid of the unit. If this does not work, change the capacitors, which need much more disassembly of the unit, mainly including removal of a metal plate that covers the front panel from behind.

To

Developers life - Bra siter

Det finns siter som jag alltid återkommer till. För att ha referenser samlade på ett ställe, lätt åtkomliga lägger jag dem här och delar samtidigt med mig av mina findings:
- https://www.codecademy.com/, interactive kurser i b.la Python
- https://www.w3schools.com/, kurser och referensmaterial i allt som har med webutveckling att göra
- pythonfiddle.com, online Python

Raspberry Zero W and Wifi

I recently bought a Raspberry Zero W and immediatly run into problem with the Wifi-connection. The problem was twofold, as is often the case with seemingly unsolvable problems. I spent the good part of an evening trying to work this ou. The root cause is that we are living in an apartement block with at least fifteen quite strong Wifi-routers around us and right across the street we have a hotel with a paywayll wifi. The Raspberry happily connected to the hotel and I mistakenly added it once, and that was enough to cause the first part of the headache. The next problem was that I routinely move our router to the least occupied frequency band, which happened to be channel 13. Maybe there were some additinoal interference not showing up in the Wifi-monitoring software I have, or the Raspberry Zero has a problem with higher channels. Anyway, the solution was twofold.

First, editing the Wifi config-file, removing the hotel Wifi that made the Raspberry to disconnect from our own router. Edit via e.g. 'sudo nano /etc/wpa_supplicant/wpa_supplicant.conf'
 Secondly, moving our router down to channel 8 which is not ideal but good enough.

An additional update to the config file added a second Wifi in the form of a mobile phone hotspot and the resulting config file can be seen below. The Raspberry takes some time to switch between the two networks.

Norman Doors revisited

Utvecklare, UX'are och i det här fallet stater skall inte designa teknik så som de själva tycker utan utgångspunkten skall alltid vara att utgå från hur människor fungerar. Svårare än så är det inte.

https://medium.com/@markzee/mh17-a-darker-truth-21dc21879fa7

Fullscreen Powershell

Av någon anledning så öppnas Powershell på samma sätt om Command, dvs ett smalt fönster som inte fyller hela skärmen. Det finns ingen enkel inställning för detta, men i posten nedan så visas en enkel lösning, skriva bara 'mode 300' i PS.

http://stackoverflow.com/questions/5197278/how-to-go-fullscreen-in-powershell

Typografi i Alien

Smalt men oerhört läsvärt och som ger perspektiv långt bortom bara typografin, om man nu inte är intresserad av bara det: https://typesetinthefuture.com/2014/12/01/alien/

Merkuriuspassage 9 maj 2016

Från balkongen. Med ett Celestron Nexstar 4 och Nikon D90, utan adapter, taget på frihand genom okularet. Därav det dåliga ljuset.