Crown PSA-2X Indicator Lights Mono Mode?

[toddalin]

They don't set a threshold. All I can see is that they prevent the output of u100d and u200d from dropping below -15.7 V. How that would false trigger the IOC lights, I don't get, either.

What's "IOC" mean?

Input/Output Comparitor. Lights up if output signal varies by more than 0.05% from the input signal.

I have noted that since I changed the existing good diode on Channel 2 to the matched pair, the one that had the good diode (Channel 2) IOC light does seem to come on more often now, more so than Channel 1 even, that was also changed.

Who knows, maybe the IOC lights would be coming on at these same times regardless but I just watch it more because of the changes? I know that the diodes have absolutely nothing to do with actual the signal path, even if the IOC light does come on more often..., only its perception of what the signal is doing.

The amp is great. The fan is extremely quiet..., much quietier than the hard drive in the DVR that runs continually 24/7. (I have to have the cabinet open with my head up to it to hear it.) There is no discernable hum or hiss even if you put your ear right up to the W15GTI that it is pushing..., effortlessly. And the amp barely even get warm whereas my Yamaha RX-Z9 gets to hot to lay your hand on.

[Rudy Kleimann]

Just a thought: maybe the output level lights are telling the truth...

Perhaps the two channels aren't running the same, gain-wise. These are older amps.

The mono bridge circuit and/or switches could be acting up, for starters. Do the left and right channel meters track the same (or closer) when the amp is run in stereo and fed the signal through a "y" adaptor?

Running a 60-cycle input signal, use your volt meter to verify that the left and right channel indicators turn on at the same input signal level and output level. Try in 2-channel mode, then in mono mode and bridged mode. Use a diode as a 1/2-wave rectifier to check each channels' output during the positive 1/2 of the cycle as well as the negative 1/2 of the cycle. Could be a problem there; after all they are class "B" circuits. The phase inverter circuit in bridge mode may be at fault. Could even be dirty, tarnished, or otherwise faulty switches. Check also for DC offset on each channels' output at idle.

Any of these problems would cause the channels to track differently, and your level indicators and the IOC is showing you that it is. A quick shot from a spray can of Caig Deoxit usually correct dirty switches, pots, and input connectors. I've revived many a piece of gear with it. Most Guitar Sinner stores have it for sale in the "Pro Audio department

[scott fitlin]

The amp is great. The fan is extremely quiet..., much quietier than the hard drive in the DVR that runs continually 24/7. (I have to have the cabinet open with my head up to it to hear it.) There is no discernable hum or hiss even if you put your ear right up to the W15GTI that it is pushing..., effortlessly. And the amp barely even get warm.

I must agree 100%. The PSA-2 is a legendary amplifier! Amazing sounding taught, and ryhmically alive, clean sub bass. And the transient punch is in the " Heart Attack " territory!

Mine run cool also, and I run em hard, all day till the wee hours of the morn!

Still works well in the future too!