Beomaster 2400: Power Supply Checks and No-Load Current Adjustment

The lamps are now all replaced and tested.  I am ready to move on to the power supply checks.

First however, I installed the Beomaster 2400 control panel and rechecked the operation of the touch buttons and lamps. This panel is sometimes tricky to install as there is a spring contact for each of the touch control buttons.  Those must all align properly to their metal posts.

Here are photos of those checks. Note that the color of the indicator lamps isn't accurate to how they actually appear in person. It is always difficult to capture lighting pictures and still have enough light to see the audio component in the photo.

...and finally...Standby

Now for the voltage checks.

First is the +15VDC power.  Here is the +15V supply reservoir capacitor. 22V at the reservoir capacitor is a good value. Next is to adjust the output of the +15VDC regulator.

The service manual says to use the 2R151 trimmer to set the +15VDC supply to +15.0V making the measurement at 2TP15.

No problems adjusting that. Now to measure the Beomaster 2400 ±31VDC supplies. I measured those voltages at the two large 5000uF reservoir capacitors (0C7 and 0C8).

I have a couple of wires connected to the test points for the Beomaster 2400 no-load current adjustments.  The space is too cramped to easily attach measurement probes across the emitter resistors (2R256 and 2R356) for this adjustment so I like to temporarily solder some test wires for the no-load adjustment. Both channels easily dialed in to the service manual stated 12mA with the multi-turn trimmers I installed earlier.

Everything tested good so I can finish up the re-assembly of this Beomaster 2400 unit.