OLED with SSD1306 debug issue

[mmarin]

Hi,
I'm looking at a problem I am having with the interface of a microcontroller to an SSD1306 based 128 x 64 OLED from Winstar. This OLED works on my previous board but don't seem to understand why it's not displaying correctly with the new custom board ?!? A little at a loss to why the Iref pin shows < 1V when I know it should be closer to 6,8V as on my previous board. Actually data sheet talks about (Vcc - 2,5)/Iref = R which works out to about 520K for 12,5uA and Vcc=about 9V. The Iref pin (and the VCOMH pin) is way below that voltage expected for the resistor. I'm baffled as this voltage is generated internally by the SSD1306 chip ...
The main difference between this new custom board and the older one is the new one uses an external Vcc set at 12V (but I'm using 9V instead for the moment). The older board used the internal charge-pump which generated about 6 - 7 volts. The Iref resistor was set at 390K and this worked no problems. With external Vcc I get no Iref voltage and this would make the brightness too low - the reason I'm not getting any display as usual.

Anyone had this problem before and what could be the reason for it ? Any thoughts on this would be greatly appreciated. Attached schematic for reference.

Cheers, Mike

[mmarin]

Nevermind, it would appear it's working now !!