Re: Denon AVR-1912
From what? The voltage regulaors?
From what? The voltage regulaors?
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Re: Denon AVR-1912
I know it's not the amp board audio transistors or resistors. Tried two amp boards. I know it's from a pioneer , but the output chips are the same and I adjusted dc offset to denon service manual specs. Kind of stumped here. The pop in the audio when i turn it on leads me to believe it's not a fault in the protection circuit, but elsewhere. Any ideas here? I'd really like to get my surround system up and running again.Comment
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Re: Denon AVR-1912
The pop is DC offset. Does it do this on all channels?
The offset occurs, for some yet unknown reason, because the conduction of the faulty channel(s) output transistors is not the same- one is powered from the positive supply and the other from the negative supply, and when all is well, in a perfect world, the conduction cancels to yield 0 volts DC offset. That unequal conduction can be from an offset voltage applied to the output stage from a previous stage, the transistors themselves, unequal power supply voltages (maybe), or something like that.
Someone mentioned the main filter caps. Did you check both rails of the power supply to see if they were equal, both with no signal and as you increased the signal? If there seems to be a problem there, be sure to carefully check the caps for value and the bridge rectifier diodes. One may be open, causing increased ripple and hum, and poor voltage regulation as the load is increased.
I don't have the schematic to look closer.Comment
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Re: Denon AVR-1912
Thanks. With check the area on the speaker board. How do i check the main rail voltage?Comment
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Re: Denon AVR-1912
Very, very carefully, of course.
Can you get to the rectifiers easily? I imagine they will be close to the main transformer and filter caps. Maybe one lead on them is marked with a + or -. Measure to the metal chassis, if you can't find the center tap of the transformer.
Another way is to be extremely careful and measure the voltage on each transistor lead. The transistor with positive voltage should have one lead that measures what the rated supply voltage is supposed to be, say + 50 volts or so. The other transistor, connected to the negative rail should have a lead that measures the same as the other rail, say -50 volts. You need the schematic to get the exact value.
Again, I don't have the schematic, but I am assuming it uses discrete output transistors in a fully complimentary configuration.
Be careful. It's easy to let a probe slip, and short the transistor leads together or to something. That almost always means blown transistors and stuff that you didn't have a moment before.
I'll look back through the thread for a schematic link.Comment
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Hello,
I know some might say... just buy another one. Sell it as parts..!
So had this AMP for quite some time. Recently I saw light smoke coming out of the AMP. Had my fire extinguisher close by. Just kidding. Turned immediately all devices off from mains.
Let things cool a bit, and opened up the amp device. I clearly saw on the main board which hosts the 5X amp (5.1), 3 10 ohms 1W resistors had their leads looking black, while the rest of the remaining 2 x 10 ohms were brownish as being installed from factory.
Spent some time downloading the Service...06-11-2024, 08:38 AM -
So like the title says, I have an old Stereo Receiver/Amplifier that I picked up from the goodwill, it's a HH Scott Model A510. When I first got it home it had zero output. Opened it up, notice the fuses are missing. Pop in 2 new fuses (AGC4A 250V) and try again, within 5 seconds the L channel fuse POP! I don't see any visible indications of damage or arc burns on the PCB, no popped resistors or diodes, no burnt traces or blown out caps. So I decide to just try another new fuse, POP. Swapped around my R and L speaker wires, and checked the integrity of all wires and connections. Everything looks... -
Hi everyone , I have a rx-A3010 that all alllll the channel working except of Front left , if someone can lead me on what to begin wit it would be very helpful
what I did so far ,
factory reset
test all other channel
tone test
dissasemble and look , visual inspection witout full dissasembly
looked at all the mosfet for temperature to see if they eas operating
scratch my head couple of time
thanks in advance all help is appreciated , service manual are welcome too ! =)... -
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Hi friends
I have reverse engineered this tester, schematic is attached and is complete except for capacitor values. These testers annoyingly have no model number but they are the ones you find on the first page of just about any website if you type in "18650 4-channel tester". There is also a 2-channel variant and a newer 8-channel variant. They are very cheap (about £15) and can measure voltage, current, internal resistance and capacity. They have a multicolour display for all these statistics. They also have terminal blocks so that if you want to use a breakout board...
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