I ran it hard with a dummy load. I have high wattage 4ohm resistors. One thing I just noticed is that when I touch the ground on the left rear channel rca. The amp goes real hard into clipping (red) and the mv goes up to about 150mv .
That is also the bad channel
The other channels do not do this to that extreme even with the gain the same.
I’m questioning that maybe the shielding is bad on the channel
That is also the bad channel
The other channels do not do this to that extreme even with the gain the same.
I’m questioning that maybe the shielding is bad on the channel
That's possible but I don't know how they're constructed.
Does it do this when that channel is on low-pass?
Does it do this when that channel is on low-pass?
Yes it does on low and all pass at 150mv.
High pass goes up to about 30mv.
When I the rca ground on that channel the dummy load gets real hot immediately
High pass goes up to about 30mv.
When I the rca ground on that channel the dummy load gets real hot immediately
I should have asked... Does the problem occur only when touched with something conductive (like your finger) or does it do the same thing if you touch it with something non-conductive, as well?
Apologies,
I was very sick
Here is a view of the rca inputs.
It only does it with my finger. If while touching the shield with one hand I touch the chassis with my other hand the noise goes away.
Currently the amp is running again. The only change that was made was biasing the bad channel up to match the rest (around 1-1.2mv).I ran it hard with the dummy load on the bad channel for hours. I also manipulated the board with a non conductive pencil using hot and cold as recommended. I still have no confidence that this will not randomly blow the channel again as this has happened a few times before.
One thing I failed to mention whether it matters or not is when the channel blows the affected speaker (channel) pops at a relatively low frequency while the others just turn off. This in turn did unfortunately kill one of my speakers. (Melted the voice coil)
Mike
I was very sick
Here is a view of the rca inputs.
It only does it with my finger. If while touching the shield with one hand I touch the chassis with my other hand the noise goes away.
Currently the amp is running again. The only change that was made was biasing the bad channel up to match the rest (around 1-1.2mv).I ran it hard with the dummy load on the bad channel for hours. I also manipulated the board with a non conductive pencil using hot and cold as recommended. I still have no confidence that this will not randomly blow the channel again as this has happened a few times before.
One thing I failed to mention whether it matters or not is when the channel blows the affected speaker (channel) pops at a relatively low frequency while the others just turn off. This in turn did unfortunately kill one of my speakers. (Melted the voice coil)
Mike
Attachments
Do you have an RCA cable you can cut or an RCA plug that you can solder wires to to test the bad channel's RCA jacks?
I want it on a plug so you can apply force to it. If you drive the same signal into both the center conductor AND the shields, there should be NO output from that channel, regardless of the input level. If moving the plug (without contact from your fingers) makes the channel intermittently produce audio, the jack may be defective.
Can you make the amp malfunction if you use the front channel inputs for all 4 channels?
I want it on a plug so you can apply force to it. If you drive the same signal into both the center conductor AND the shields, there should be NO output from that channel, regardless of the input level. If moving the plug (without contact from your fingers) makes the channel intermittently produce audio, the jack may be defective.
Can you make the amp malfunction if you use the front channel inputs for all 4 channels?
Hi Perry,
I do have a set of sacrificial cables I can use.
Are you wanting me to connect the center pin and the shield together and feed a signal to it while applying force in various directions when plugged in?
Also I’m unsure about the front channels.
Do you mean input rca’s into the front to get an output on all channels? I think I’m misunderstanding
I do have a set of sacrificial cables I can use.
Are you wanting me to connect the center pin and the shield together and feed a signal to it while applying force in various directions when plugged in?
Also I’m unsure about the front channels.
Do you mean input rca’s into the front to get an output on all channels? I think I’m misunderstanding
Yes on the RCAs and signal.
Does the amp have a switch to allow all 4 channels to be fed from only the 2 front RCA inputs?
Does the amp have a switch to allow all 4 channels to be fed from only the 2 front RCA inputs?