Hi
Long story short, amp turns on but produces gibberish at it's output. No shorted, burnt, damaged stuff.
Quick check did not find any missing or out of tolerance auxiliary or main supply voltages. All seems fine. No heating.
I've checked the class D switching frequency , one of the drivers (IR2010) is switching at 120khz but the other one at 330khz. Shouldn't they produce the same ? Shape is also a bit odd for the 120khz.
The inputs to the drivers (HIN and LIN) are inline with the output(LO and HO), so 120khz comes in 120khz comes out, so I suppose it's not the ICs...it is doing what it's being told to do so.
I do have a service manual but it's for the bigger brother from the same series Alpine MRD-M1005, so i've used that as a reference. I'm trying to understand what is setting the switching frequency input to the driver and why it is so much different.
Long story short, amp turns on but produces gibberish at it's output. No shorted, burnt, damaged stuff.
Quick check did not find any missing or out of tolerance auxiliary or main supply voltages. All seems fine. No heating.
I've checked the class D switching frequency , one of the drivers (IR2010) is switching at 120khz but the other one at 330khz. Shouldn't they produce the same ? Shape is also a bit odd for the 120khz.
The inputs to the drivers (HIN and LIN) are inline with the output(LO and HO), so 120khz comes in 120khz comes out, so I suppose it's not the ICs...it is doing what it's being told to do so.
I do have a service manual but it's for the bigger brother from the same series Alpine MRD-M1005, so i've used that as a reference. I'm trying to understand what is setting the switching frequency input to the driver and why it is so much different.
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I have an MRP-M1000 that has a bad op-amp that's causing the same issue. The op-amp wasn't readily available and the amp was doing what I needed so I never replaced the op-amp. One op-amp in your amp could be damaged and causing this problem. In the 1000, it was a 2-channel op-amp for both channels. Yours has two op-amps. You could try swapping them to see if the problem followed one of the op-amps.
The amp is two discrete self-oscillating amp circuits so, even if all is working properly, the oscillation frequency won't be identical.
I have an MRP-M1000 that has a bad op-amp that's causing the same issue. The op-amp wasn't readily available and the amp was doing what I needed so I never replaced the op-amp. One op-amp in your amp could be damaged and causing this problem. In the 1000, it was a 2-channel op-amp for both channels. Yours has two op-amps. You could try swapping them to see if the problem followed one of the op-amps.
The amp is two discrete self-oscillating amp circuits so, even if all is working properly, the oscillation frequency won't be identical.