Hi all, I have a Denon 760BL on the bench with odd output issues.
When set to 4ch mode Unbalanced
Channel A input
Output is as follows
Ch A
Left is low distorted,
Right is normal
Ch B
Left is low distorted
Right is normal
When set to 4ch mode Unbalanced
Channel B input
Ch A
Left is normal
Right has no audio
Ch B
Left is high vol distorted
Right is high vol distorted
Turning up input sensitivity on input B causes the amp to trip the relays and it won't turn back on unless the gain is turned down.
I've removed the veritcle boards, cleaned the pots and switches with deoxit and no difference.
The amp idles at around 2 amps
Turning up the gain on input b causes it to draw excessive current then it trips the fuses.
Any help appreciated. Thanks
When set to 4ch mode Unbalanced
Channel A input
Output is as follows
Ch A
Left is low distorted,
Right is normal
Ch B
Left is low distorted
Right is normal
When set to 4ch mode Unbalanced
Channel B input
Ch A
Left is normal
Right has no audio
Ch B
Left is high vol distorted
Right is high vol distorted
Turning up input sensitivity on input B causes the amp to trip the relays and it won't turn back on unless the gain is turned down.
I've removed the veritcle boards, cleaned the pots and switches with deoxit and no difference.
The amp idles at around 2 amps
Turning up the gain on input b causes it to draw excessive current then it trips the fuses.
Any help appreciated. Thanks
Is the problem associated with a specific level of the output or is it associated with the gain control itself. People adjust the gain on the amp instead of with the signal source and it confuses the issue.
Hello Perry
I've discovered the issue isn't output level or gain level associated.
I swapped the source unit for another just incase the input signal was bad and no change.
When I use input A and set the amp to 2ch mode bridging the speaker outputs on ch A and ch B causes the amp to trip and shut down, in fact it makes the relays vibrate/buzz they're tripping so fast.
I've discovered the issue isn't output level or gain level associated.
I swapped the source unit for another just incase the input signal was bad and no change.
When I use input A and set the amp to 2ch mode bridging the speaker outputs on ch A and ch B causes the amp to trip and shut down, in fact it makes the relays vibrate/buzz they're tripping so fast.
What does the output look like on those channels when the relays disengage?
What if you load only one at a time? Does it shut down with either of the channels loaded alone?
What if you load only one at a time? Does it shut down with either of the channels loaded alone?
I don't have a scope to check what the channels look like with relays disengaged.
Input A = Loading one at a time returns the same result as loading both
Input B = similar result however the relays don't trip instantly as they do on input A.
Input A = Loading one at a time returns the same result as loading both
Input B = similar result however the relays don't trip instantly as they do on input A.
Is the 12v power supply sufficient to power the amp at the power levels you're testing at?
Does the amp shut down at the exact same output voltage (at the speaker terminals) whether the amp is driving one channel or two?
Or can you drive one channel alone to a higher output before the amp shuts down?
Does the amp shut down at the exact same output voltage (at the speaker terminals) whether the amp is driving one channel or two?
Or can you drive one channel alone to a higher output before the amp shuts down?
My bench supply is 13.8v 30 amp has no trouble powering most amps
I don't know how to test the speaker voltage when it shuts down, I tested with meter set to DC and it read open circuit when the amp shut down.
When driving one channel it will play at low volume it goes higher if I turn it up thennit cuts out.
The audio has a distinct echo on channel A right spk and a strange bass tone on channel B right speaker
I don't know how to test the speaker voltage when it shuts down, I tested with meter set to DC and it read open circuit when the amp shut down.
When driving one channel it will play at low volume it goes higher if I turn it up thennit cuts out.
The audio has a distinct echo on channel A right spk and a strange bass tone on channel B right speaker
Is the shield ground on your signal source intact?
Measure the AC voltage with a multimeter driving 1 load or 2 leads and compare the voltage at the point where the amp shuts down.
Measure the AC voltage with a multimeter driving 1 load or 2 leads and compare the voltage at the point where the amp shuts down.
The amp just blew a 30amp fuse F501, F501 is on the right side of the board I was testing a right channel when it blew
Also when input B's ground shield touches the output shield it causes the amp to shut down
Input A's input and output shields don't cause it to shut down
Input A's input and output shields don't cause it to shut down
Did you ever have a scope?
Use a lower rated fuse (10A) for testing. It will help protect the amp.
Use a lower rated fuse (10A) for testing. It will help protect the amp.
No but I'll try and aquire one right away.
The amp has 2x 30amp fuses built in, it was one of those that blew.
The amp has 2x 30amp fuses built in, it was one of those that blew.
Don't buy one unless you know precisely what you need. If you don't know, post links to the scope you are looking at.
The value of those fuses are for normal operation. For testing, you should use something much lower rated.
The value of those fuses are for normal operation. For testing, you should use something much lower rated.
I MUCH prefer an analog scope but it's nearly impossible to get anyone to buy one. 2-channel is good enough but if you find a good deal for a 4-channel, there's no problem having 4 channels.