If I pull pin 10 and pin 9 on the op amp the triangle. Waveform on pin 7 of the 4080 is gone or flat line
No.
It could be defective. It's not a particularly special op-amp like the 2274. Any 4 channel op-amp should work, for testing.
Is this amp like the fusion amp I asked about previously?
It could be defective. It's not a particularly special op-amp like the 2274. Any 4 channel op-amp should work, for testing.
Is this amp like the fusion amp I asked about previously?
https://elektrotanya.com/showresult?what=fp9001&kategoria=&kat2=all
Download the manual and look at the circuit. I figured you would have already had it.
Download the manual and look at the circuit. I figured you would have already had it.
FYI, The 10 turn POT is for current overload threshold. Same for the Earthquake. You should leave it where it is. Check the 2.2ohm 3w resistor behind the cap and make sure it's in tolerance. It likes to open up when the amp is clipped hard.
Do you have the correct setting for the pot's output to the comparator (to avoid having to do additional trial and error testing to get an acceptable trip point)?
Negative. I avoid fooling with it. Last time I did one I turned it all the way off. I then drove the amp hard into it's advertised minimum load and turned it up until trip. Then I dialed it back 1 turn. I halved the load and it tripped. Hardly scientific but seemed sufficient. I should probably take better notes about these thing!
I took notes for 20 of the 30 years I worked and it wasn't enough.
The way you did it will work. You could also measure (accurately) the shunt resistor value and use the rail voltage across the lowest rated load (giving current at full power) to get a voltage across the shunt at full power. Then use that to set the comparator trip point.
The way you did it will work. You could also measure (accurately) the shunt resistor value and use the rail voltage across the lowest rated load (giving current at full power) to get a voltage across the shunt at full power. Then use that to set the comparator trip point.
1. That 2.2 ohm resistor behind the no polar cap reads 2.4ohm
2. As for the current protection not sure if it’s set correctly but will tackle that once I can get a clean audio waveform after cranking the gain up, he. When the audio starts to breakup you. A start to hear the high frequency coming from the board. I have tried changing every ic on the board and wiggled every component and no change on the distortion of the wavforme
2. As for the current protection not sure if it’s set correctly but will tackle that once I can get a clean audio waveform after cranking the gain up, he. When the audio starts to breakup you. A start to hear the high frequency coming from the board. I have tried changing every ic on the board and wiggled every component and no change on the distortion of the wavforme
Did you replace the output cap with one that was within tolerance?
Does this amp use the JFET in the protection circuit?
Does this amp use the JFET in the protection circuit?
I own a bunch of the amps from this series. This one is essentially a de-scaled version of the D300/200/100HC. The Earthquake 200DHC Schematic is similar, just not spot on. The Bipolar cap needs to meet or exceed the rail voltage in it's power rating. Make sure that it does. I cannot recall how muting was handled on these but check the small number of to-92 transistors on the board for a j-fet. Might check that for audio signal to confirm. I'm sorry I cannot be of more help. I have one here on the 'someday shelf' with the same symptoms so i'm watching with interest. Seems to be a lot of threads with 4080 amps and a similar issue that were never resolved. user @rdiaz has a lot of notes on these amplifiers and may be able to help as well. Good luck!
So for the time being I was able to install 2 polarized caps in series just for testing, that did clean up my waveform.
Unfortunately, I still have some scratchy frequency from the subwoofer when connected with no Audio playing. There is still around 0.5vdc across speaker terminals when volume down
Unfortunately, I still have some scratchy frequency from the subwoofer when connected with no Audio playing. There is still around 0.5vdc across speaker terminals when volume down
What is the DC voltage measured directly across pins 9 and 10 of U2?
Do you see noise on pins 8, 9 or 10 of U2?
Do you see noise on pins 8, 9 or 10 of U2?
Across pin 9 & 10 is 0.028vdc
No noise on either pin
Pin 8 triangle waveform
Pin 9 &10 flat line
No noise on either pin
Pin 8 triangle waveform
Pin 9 &10 flat line