HK AVR 125 display strobing and no sound, even in headphone jack

could be a bad headphone jack. There was a commong problem with denon receivers around that time where the headphone jack had contacts that would short and make the unit act like there were headphone plugged in even when there wasn't. Sometimes you can clear the error by inserting a headphone plug and unplugging it a couple times. If it continues to happen, then you can get the headphone jack replaced.

The unit thinks there are headphone plugged in even when there are not. You need to have the headphone jack replaced. This is a common problem with this model. Another way to fix it if you don't plan on using the headphone jack is to unplug the cable going to the headphone jack board. This will disable the headphone jack, and stop it from sending an erroneous signal to the micro.

Sorry. They are not compatible. The headphone jack is an output but you need an input for a guitar or bass. You will certainly damage the HK if you continue. There are no compatable inputs on the HK. The inputs are meant to be used with a 300mv output device, such as a CD or DVD.

Need to either unplug the cable to the headphone jack board (if you don't want to use the headphone jack), or have the jack replaced. This is a common problem with these models. The is a short in the headphone jack that makes the unit intermittently think there is a set of headphones plugged in even when there isn't.

check to see if there is audio from the headphone jack. These unit have a history of bad headphone jacks that cause the unit to think there are headphones plugged in even when there isn't. Sometimes plugging phones in and taking them out will fix the problem for a while.

Try inserting a headphone plug into the headphone jack and remove it. Sometimes these units have a problem in the headphone jack where the unit thinks there are headphones plugged in even when there isn't. This cuts all the audio output to the speaker jacks. If you never plan on using the headphone jack, you can also go inside of unit and unplug the cable that goes to the headphone jack board. Just make sure you unplug the unit before you do this, the plug is close to the main power switch.

try geting a new jack if not bye a now wone

had same problem with my denon 1910 .... clicking with no sound and some modes indicating not available. Blowing the dust out of the headphone jack solved the problem !!!!!!!!!!!!! ... the denon people could not even figure it out. Thanks sooooo much.

Check and see if you don't have a auto dim setting on or you changed Display setting.

I have same Amp and this happened to me also.

If you want to fix it:

It must be a contact problem arount the power switch, power cable, fuse or the condensator area.
Maybe you can se a black color on the board.
And checking the solderind points with a magnifyer can help too.

Thats all from that distence.