Notes
1. 1uF C6A & C6B are the release time caps and wired in parallel to make a 2uF cap.
If you have a capacitance meter, you can measure the capacitance of all the 1uF caps to match C6A & C6B on the left and right to ensure a matching release time.
If no capacitance meter is available, it is easy to add a 0.1uF cap to a 0.33uF cap under the PCB to the faster release channel during final testing to match.
2. Occasionally, you may see the last few bottom LEDs very slow release on a channel, First clean the solder side of the PCB with alcohol and an old toothbrush and retest. If this doesn't fix the problem, it can be caused by an out-of-spec TL074B. This can be proved by swapping the TL074B opamps between left and right to see if the problem follows the opamp or stays with the channel.
PCB Component Build maps
Display PCB
http://jlmaudio.com/builds/maps/VUPPM50 ... y_map.html
MAIN CPU PCB
http://jlmaudio.com/builds/maps/VUPPM500_map.html
COMPACT ANALOG PCB
http://jlmaudio.com/builds/maps/VUPPM50 ... g_map.html
Test procedure Analog input
Power up VUPPM Compact with the bottom of case removed so you have access to the 4 trimpots.
Press Meter Mode and Peak Mode together to go into led test mode. This shows all green then all orange and then all red.
Press peak reset to set brightness level to LOW, MEDIUM, HIGH.
Press either Meter Mode and Peak Mode to leave led test mode.
Send in 1k tone at 0dFS or +18dBu to 500 Input for left and Output for right.
Set mode to VUPPM mode RED PPM with GREEN VU over the top.
Adjust Left and Right level trimpots so left and right 40th red led just light.
Adjust Left and Right VU/PPM trimpots so left and right green led just light. (40th led may make yellow depending on peak mode)
