CAN YOU SEND THIS PROTECT CCT ON MY E-MAIL ptinarwo@sirdc.ac.zw i am finalising my B500 AMP. thank you
I cosidering to add signal led, fan control, VI limiter, triple darlington...
Hy! I measured BIAS, it's 30-35mA in cold state for both panels. I will make the other measures as i get home from work. Do i have to measure voltage between power gnd and Z1, Z2, R20, R21?
And one more thing: I didn't connect POWER GND to SIGNAL GND, can it be the problem? But if yes, why has one of the panels 7mV DC offset (i measured it again) and the other 300mV? I can't figure it out.
Any ideas are welcome.
Measure voltage across Z1, Z2, R20, R21. Try to use mached 2N5401/5551 and MJE340/350.
Yes, just 22k from overcurrent detect connect to used 0.33R/5W, +/-50V no changes for single pair.
Checked voltages
L Z1: 14,2V
L Z2: 14,4V
L R20: 446mV
L R21: 440mV
R Z1: 14,7V
R Z2: 14,3V
R R20: 444mV
R R21: 438mV
I used matched transistors (from the same series, and they were chosen from 15's batch with multimeter's HFE) and i used the closest possible values.
When i connect signal gnd to power gnd every reading is just fine (7-8mV offset on both panels) the 300mV offset only occours when the input pins left floating or the signal gnd is not connected to power gnd.
If it is a solution, to connect them together, then it will stay in this state.
Hello! I checked the voltages, the L and R indicates wich panel I am talking about. The R is the one with the high DC offset, the L was good so far.
L Z1: 14,2V
L Z2: 14,4V
L R20: 446mV
L R21: 440mV
R Z1: 14,7V
R Z2: 14,3V
R R20: 444mV
R R21: 438mV
I used matched transistors (from the same series, and they were chosen from 15's batch with multimeter's HFE) and i used the closest possible values.
When i connect signal gnd to power gnd every reading is just fine (7-8mV offset on both panels) the 300mV offset only occours when the input pins left floating or the signal gnd is not connected to power gnd.
If it is a solution, to connect them together, then it will stay in this state.
BX500 PCB design
Hi Miles....you mentioned that you were going to add these three things, are you redesigning the B500 pcb....I have added the indicator leds to my personal version of the pcb, but would like to see what your design comes out like...it is getting a bit too much for me to modify now, but I do like the XLR input stage you added a few days ago, it makes a lot of sense and actually saved me another board that had a preamp on it...less is better..still waiting to see how you will redesign the B500 to become a BX500.....