Yamaha CR-620 Overheating...

[ndstudio]

Hey all,

Setup:
Yamaha CR-620
Yamaha YP-211
2x Legend Audio Speakers - 8ohm 100w Max
Yamaha YST-SW45 (Active Powered)

My Yamaha CR-620 Receiver started to overheat and I cant seem to figure out why... I first noticed a smell coming from my A/V setup about 4 months ago but it soon went away. I figured it was just some dust getting inside the vents of the receiver or something and causing the smell. Then last week I noticed the smell came back and soon realized the smell was coming from the CR-620. Turns out that there is a lot of heat coming out of the left side of the receiver where the transformer is located. I started to use an Infrared Thermometer (see attached) to track the heat and the unit would heat up immediately when I turn it on and would start to rise in temperature all the way to 160F... (obviously I would turn it off at this point).

Oddly enough, last night I wiggled the knobs, turned it on and off multiple times and rewired the speaker connections and the heat has dissipated to about 85F degrees which I left on for about 2 hours last night and again for 2 hours this morning and everything was fine.

So at this point I don't know whats going on... Part of me thinks that the wiring to the speakers could have been the issue? and another part of me thinks somethings up with the transformer. Nothings on top of the receiver preventing airflow and it is sitting on top of a long TV stand that I am using for my Hi-Fi setup. (see attached photo).

Can a [potential] loose connection to the speakers cause overheating? Any help on this would be greatly appreciated! I love this receiver and its the heart of my Entertainment / Hi-Fi system setup.

 

[avionic]

Welcome aboard AK.....

Turns out that there is a lot of heat coming out of the left side of the receiver where the transformer is located.

And the output transistors. Download the service manual and try to do the idle current adjustment of the main amplifiers. If the unit is dusty inside. Blow it out or vacuum it out.

 

[avionic]

Download the service manual and try to do the idle current adjustment of the main amplifiers.

page 10 in the service manual.

idle current is the bias adjustment. The higher the bias current , the more heat is generated by the output transistors.

 

[avionic]

. Part of me thinks that the wiring to the speakers could have been the issue? and another part of me thinks somethings up with the transformer.

If it was the transformer it would probably be a permanent issue.What are you using for speaker wire?

 

[avionic]

page 10 in the service manual.

http://sportsbil.com/yamaha/cr-620-s-idle.pdf

 

[avionic]

Be extremely careful not to short out anything with your meter test leads. Highly recommend mini-grabbers.

 

[ndstudio]

Thanks for all the input Avionic and thanks for the kind welcome!

So, I will start by cleaning out the inside of the receiver. Then I will move on to trying to do the idle current adjustment. I have worked with circuitry before but only very small 5v or 3.3v systems. (eurorack stuff) I am a little intimidated by the schematic / service manual procedure so I might have to take this to a professional in town. BTW, my multimeter doesn't have those grabbers, it has the alligator clamps.

I am currently listening to music with it just fine, but that still doesn't mean anything when just 2 days ago it was over 160F degrees...

As for wire, I'm not really sure, I am using your standard gauge speaker wire. Nothing super fancy but from what I can tell its about as standard as I can find. I will try and do more investigating on the speaker wire in the morning.

EDIT: When I went to reconnect the speaker wire and wiggle the knobs to try and fix the issue 2 days ago, I did notice that the speaker wire connector screws on the speakers were not really tightened all the way down. So this still begs the question, is it possible for a loose connection to somehow make the receiver get hot???

Thanks again Avionic! I will try cleaning this receiver out in the AM.

 

[ndstudio]

Just wanted to circle back around on this.

Speaker wire is 16 gauge. Not sure if a loose connection was the issue but I have not experienced any more problems with the unit. I have left the receiver on all day and at times set it to medium to high volume and it still operates at a normal 85F temperature. So problem solved (for now).

Any ideas in to what could have caused the spike in temperature?