Orion 3000.1DSPLX V4 - No Output switching

Weird one, new amp, very little play time, I get it in, can see nor probe anything damaged. I notice output is not switching but power supply and rectifiers have proper waveforms. Also weird is each IR2110s on each card is getting -102v to everything, vCC, In, Out, etc. gates of low side FETs getting -102v and middle leg of high side getting -102. When I pull the output cards output high side gets +102v (from what scope is telling me) Also when trace back preamp I get this wave from 1st opamp all the way to output riser cards even tho is is getting fed a proper 75Hz sine wave @ 1v.

Never seen an amp give -102v to so many complements and leads, or even one for that matter, and never seen a preamp sinewave like that. No idea where to even start as I’m used to the version 2 3kDSPLX where the middle riser card feeds the low side signal after getting it from preamp. Seems they totally changed the design (and used weaker FETs)

Is that 38483B supossed to be what feeds the low side drive wave to output section? Datasheet says pin 6 is output (direct drive power mosfet) but it doesn’t look like anything I recognize. So many firsts for me on this amp, really reminds me how much I still have to learn.


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No but their is a spot for one @ SVR1.

I’ve noticed more then once that some Orion Amps of the same exact version/revision sometimes have the pots and sometimes do not. Very odd

Of note; there is one on my HCCA 5000.1D that has no use that I know of, does not effect wave at speaker terminals (+\-) or dc offset.


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Wow, so IC172 is throwing up some weird waveforms I’ve never seen before. I tried snapping some pics during the video inbetween the waveforms transition to show what each pin is doing, Pin 1 is growing and shrinking back and forth like pic 1 shows, and Pin 7 is doing something similar as in pic 2. Looks as if both of waveforms are stuck in a loop trying to build but once it does it reverts and on and on.


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Not that I can see, unless this is considered it in pics, but by pulsing I’m used to very distinctive pulses. This just looks like feedback to me, both ends of both output inductors are 2v/Div, no output cards in. I would say no, but …


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I’m prolly overthinking this as well, signal looked like a flat line at 10v/div@10us, slightly bouncing like a sinewave that was zoomed in on too close in a way, not the typical pulsing I’m used to seeing, zooming out to 1v/div@50ms shows the below pic. This is without the output cards installed.


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Yes, initially it looked like a flat line but I adjusted scope til I got that. Yes it is pin 8/VCC of the LM393-ic172. And ya it does look like pulsing to me, but it’s very fast, not the 1-2 a second like you’re saying. when I had it zoomed out at .5 sec it was hard to differentiate the spikes but when zoomed to 100ms it looks like above picture, 2v/div. Auto set just looks like bouncing noise. So no I don’t think it’s pulsing, but it is doing that in pic


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Yes, rail voltage is constant @ 103.5v / -104v.

No, main power supply is not switching on and off, idle current steady at 2.5a, amp does ramp up to 4a idle, which is full amp operation but settles back down to 2.5a

Aux power supply seems way off tho, 1st pic is the IRFBC30 wave at middle leg, nothing detected on outer legs. Something seems off with the transistor signal tho, never seen it like this. Also the UC3843b seems to be “funky” as well, 2nd pic is of pin 4, proving it causes a little transformer noise and amp to pull an additional 1.5a, 3rd pic is of the wave on output/pin 6 of the UC3843b. I’m thinking maybe the UC3843b is shot? All Orion amps Ive repaired have the same Aux Power supply components and I’ve never seen them act like this.


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Pin 1: -91v
Pin 2: -96.3v
Pin 3: -98v
Pin 4: -95.5v (feedback and double amperage draw when I prove this pin)
Pin 5: -103.3v
Pin 6: -96v
Pin 7: -104v
Pin 8: -104v

I use my digital multi meter cuz my probe is off by a few volts, sometimes by 10+ at that high a voltage :/ The gates to the Low side FETs are also reading -104v. I also notice sometimes current pull is 2.8a and other times 2a. So something is def off somewhere. I’m thinking I should pull output FETs just to see? So weird bro. And sorry about the slow replies, getting swamped with other stuff and this is so frustrating, never seen anything like it.
Ok, so really weird. Neither IR2110s would have anything hi or lo in, but soon as I probed pin 4 of the 3843 that made amp make a feedback sound and make idle current jump 6+ idle current would steady to 3a vs 2.4a beforehand. waveform on the IRFBC30 would “stabilize” and the IR2110s would have hi in waves

That feedback and idle current doubling when probing pin4 of the 3843 wild happen wether I used scope probe or multimeter probe.

Yes, my bad I will reverse leads 😅