This old amp is going into protection mode upon power up. Normally on initial power up the protection light blinks for a few seconds then you hear a relay click and protection light goes off. Now it is goes through the same steps only when the relay clicks the protection light does go out but after about a second it comes back on.
I opened the case and found what looks like a burnt resistor. See the attached pictures. This seems like an obvious problem and a I plan on replacing it but it may not be the primary problem.
Do you guys have any comments or suggestions?
Regards,
Darrell
I opened the case and found what looks like a burnt resistor. See the attached pictures. This seems like an obvious problem and a I plan on replacing it but it may not be the primary problem.
Do you guys have any comments or suggestions?
Regards,
Darrell
Attachments
There are at least three more (unless R508 got caught in the blast) that look frazzled in that picture.
Not good tbh, as they are in the small signal stages.
Has this unit got some hidden history or have you been attempting to modify it ? R518 is (was) a 4.7 ohm on the second long tailed pair. Hard to see how that could fry.
Not good tbh, as they are in the small signal stages.
Has this unit got some hidden history or have you been attempting to modify it ? R518 is (was) a 4.7 ohm on the second long tailed pair. Hard to see how that could fry.
Hi Mooly,
Thanks for the quick reply. I see what you are saying about there being others burnt. I have owned this amp for about thirty years, purchased new. I may have replaced a fuse in it once upon a time but nothing other than that.
I can see this going over my head fairly fast. I think it might be worth the effort to replace a few of these components and see where that gets me. Any other advice would be appreciated.
Thanks for the quick reply. I see what you are saying about there being others burnt. I have owned this amp for about thirty years, purchased new. I may have replaced a fuse in it once upon a time but nothing other than that.
I can see this going over my head fairly fast. I think it might be worth the effort to replace a few of these components and see where that gets me. Any other advice would be appreciated.
Replacing parts without detailed testing is going to be a waste of time and money here. You don't get damage like that without finding other failed parts (semiconductors). I can't see an obvious low impedance path that could pass enough current to fry R518 for example. Its in series with 820 ohms...
It reminds me more of the random sort of problems you see with lightning damage.
So you are looking at testing all the semiconductors in that immediate area and replacing as required. Even then its not straightforward because this type of design may (may !) be somewhat critical on the devices used.
It reminds me more of the random sort of problems you see with lightning damage.
So you are looking at testing all the semiconductors in that immediate area and replacing as required. Even then its not straightforward because this type of design may (may !) be somewhat critical on the devices used.
Hi axiscat,
I was authorized warranty for Denon for many years. Please take the amplifier into a good audio repair shop. If they did Denon warranty, so much the better. It's a really nice amplifier and bad service can destroy it easily.
Why? Because Mooly is exactly right.
-Chris
I was authorized warranty for Denon for many years. Please take the amplifier into a good audio repair shop. If they did Denon warranty, so much the better. It's a really nice amplifier and bad service can destroy it easily.
Why? Because Mooly is exactly right.
-Chris
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