Denon Amplifier Repairs
This would make a very unusual put-put sound, hum or a buzzing noise depending on how it was feeling and also varied with the volume control. After going over a myriad (how many is a myriad?) of suspect looking dry joints and switch cleaning the plug in connectors on the main board it eventually disappeared. Sounded really good when it was working correctly.
This one worked but was distorting the left channel. I found the direct switch had bad contacts then noticed the left channel didn't go to class A temperature. The small green relay wasn't working, I have not seen these relays before although similar ones are usually found in cassette decks.
This was not energizing the relay. The transistor driver was faulty. I changed the rectifier diodes as the forward voltage varied quite a bit between them. The transistors in the preamp were replaced as the sound varied and distorted.