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Post by Michael on Aug 20, 2013 6:07:06 GMT -5
I have a Yamaha reciever / Amp (HTR-5280) that does not turn on. The unit was ON and runing on high volume when it shut down and never came back ON again. I suspect that it overheated it used to make a clicking sound when I pushed the power button and now it stopped . Following your other threads, I have done some tests on the power board and these are the results;
1- voltage test on F301, MG to S12, my reading fluctuates between 7.03 to 11.86. More steady on 7.03.
2- R301= 2.150 k ohm
3- on Q301, I get no reading on legs 2 and 3 (OL). Other legs;
1-2= 0.729
1-3= 0.615
Any idea what's going on here. Any help is appreciated. Thank you.
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Post by mastertech on Aug 20, 2013 9:53:03 GMT -5
That 12v should not be bouncing around. Locate D301 which is near the relay and lift 1 leg and test it with your DMM. Leave it lifted and check the S12 voltage and see if it is still bouncing. If it is then reinstall the diode and post back.
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Post by Michael on Aug 26, 2013 11:22:56 GMT -5
D301 with one leg lifted; CB 301 MG to S12, tested, Voltage steady at 17.27 V
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Post by mastertech on Aug 26, 2013 12:00:29 GMT -5
Interesting. Did you try hitting the power button with that leg lifted?
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Post by Michael on Aug 26, 2013 12:08:12 GMT -5
I did, and it made a low buzzing sound. Unit did not turn on...
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Post by mastertech on Aug 26, 2013 12:26:03 GMT -5
Remove Q301 and put in a jumper wire between collector and emitter. These 2 are not tied to R301. When you plug in the receiver you should hear relay RY301 click and unit should turn on, without hitting the power button. If it does come on and the display lights up, unplug it because it may be going into protection shutdown normally and the jumper will bypass that.
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Post by Michael on Aug 26, 2013 13:23:57 GMT -5
Q301 has 3 legs; one connects to CB301, a center with no connection and the third which connects to R301. I put a jumper wire on the one connects to CB 301 and the center. Connected the power, relay clicked, fuse F302 blew. Display did not turn on. Unplugged immediately.
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Post by Michael Jani on Aug 26, 2013 13:28:39 GMT -5
Should I replace Q301 and the lifted leg of the D301 at this time?
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Post by mastertech on Aug 26, 2013 14:22:15 GMT -5
Not yet. Does your receiver have the voltage selector switch on the back?
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Post by Michael on Aug 26, 2013 14:45:07 GMT -5
No.
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Post by mastertech on Aug 26, 2013 15:19:29 GMT -5
Well it looks like your the lucky owner of a unit where stuff has to be unsoldered to test further. Blowing F302 indicates the main transformer is being overloaded. I'm trying to find the easiest way to start looking for the problem.
Lets try this. On the front of the large heatsink there is a regulator board with 5 regulators attached to it. Set your DMM to diode test and just test to see if any of the individual regulator legs show a short to each other. Post back your results.
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Post by Michael on Aug 26, 2013 15:49:28 GMT -5
Looks like three of the 5 regulators are the same and the other two are different. They each have 3 legs. Can you please be more specific about testing them
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Post by Michael on Aug 26, 2013 15:53:26 GMT -5
All of them give a 0.000 readings!
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Post by mastertech on Aug 26, 2013 16:00:18 GMT -5
Your testing each regulator, 1 at a time and just looking to see if it shows a short between any legs.
If your second post was correct then your going to have to remove that board and test each regulator again. Looks like 1 harness has to be unsoldered. The other one should be removable harness.
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Post by Michael on Aug 26, 2013 16:25:32 GMT -5
I get the same readings!!
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