Obx - Building Tips

If soldering small items is a problem try fixing it while solder the first pin.

There are some slightly different HAA15-0.8-A Power supply out there. Mine is different from this: http://www.cs80.com/crowbx/psmod.html

Mine has a slightly different layout. I used two 2k2 Ohm resistors. parallel to R52 and R79.

The Voltage is now adjustable between 8- and 20Volts.

So no Problem to justify for 19Volts.

• Voice Card BOM Typo:
  correct: Optional: for compliance with Oberheim ECO for PW trimming on VCOs, change R73/R74 to 46.4K 1% and R15/R16 to 34.8K 1%

• IC3 (CD4011) is lacking in the BOM

You have to solder a diode at the output of the 15V regulators

Documents:

Crowbx_calibration_host.pdf

Crowbx_mount_calibration_carrier_rev1.pdf

Power issues:

the Linear PSU´s have on startup some issues to bring both voltages (-15/+15V) at the same time, in result the voltage regulators blows on obx.

in my modular system i have on high load similar issue with this rootcause..

(picture from http://www.modularsynthesis.com/modules/DJB-power/djbpower.htm )

Open

Calibration Issues:

Hint for calibrate the Voicecards:

The IC1 and IC4 must not be inserted while doing the calibration, because the DMM- OHMs measurement injects to much voltage which falsify the measure.

Hopefully the Green Lines shows where the Testpoints are

The both multiturn pots must be adjusted to 61K.

Photos
	Voicecard passive Calibration
Knops are possible, but overlapping with white engravment :-(		Alignment Test of Switches,LED and Pot	Tempco with heat transfer paste
Just a spacing test before full soldering			Just a spacing test before full soldering
Resistors soldert well, almost	3500 parts	blank pcbs	Modify the HAA15-0.8-A