Hi everyone ! I'm trying to fix a mackie hd1531 amplifier module ! the problem is that I have no audio output on the mids and trebles! after checking the output mosfets I noticed that with the oscilloscope I don't have the clock signal for the 2 IRS20957s! I added the circuit diagram ! If you have any suggestions I'd be happy
Have you tried checking power (+/-15v) to those U13, U20 op amps? ... or quickly replacing them with any substitute TL082, TL072, NE5532, 4558, etc. . Or tracing back on M-in & H-in to check for signal?
More info on what you have investigated already would help ... 🙂
More info on what you have investigated already would help ... 🙂
the supply voltage is perfect! I have +/- 15V, I tried to replace the original ADTL082 with TL082CD but the problem remains
Have you followed M-In & H-In backwards and checked U9 (op-amp) and U8 (DAC) etc. ?
e.g. just U9 failing could cause your fault.
e.g. just U9 failing could cause your fault.
I checked the input signal by connecting my generator to the signal input connector and with the oscilloscope I saw the signal on the capacitors C95 and C123
the u 13 output is not short to ground ! the thing that makes me think is to try to change the bav99 diodes or the passive components C28,C92,R25,R140,C59,C121!
it is possible that some leaky passive component is causing this anomaly ?
it is possible that some leaky passive component is causing this anomaly ?
I tried to replace the 1 nF capacitors, I tried to replace the IRS20957 driver, I changed the TL082 again, but I still have the same problem! at this point I think I just have to try to replace the 1.6Mohm resistor and to check the resistors R32 and R42 and C88; maybe i think OCSET's irs 20957 has some problem ?
Good morning ! I finally found the problem! The problem was the connection of the 18v to the IN pin of U2! The runway was interrupted and the 12 V did not arrive at IRS20957! Now I have the square wave finally in the final stage !! Thank you all
