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Denon AVR2105 Help Please if Can? New Member Hello to All.

justme1971

Jun 21, 2015
3
Joined
Jun 21, 2015
Messages
3
Here goes, forgive my spelling mistakes lol. I have a Denon AVR2105. My son seems he was at playing full volume for about 10 to 15 mins after he hooked up a CD player, that he sat on top of the unit blocking off the vents on top. Then when I came home to watch a movie the system was not working. Only came on for a few seconds and went into protect mode. So I asked my son if he knew why was not working he, told me what he had done. So I tried to reset the unit no luck, then I unplugged the unit for that night, and the next day tested it again still no luck. So I unhooked all of the speakrs 2 sets of Bose 901's VI and 1 set of 301's V and a JBL 12 inch sub and tested them on another AVR and found 1 of the Bose 901's was blown very unhappy.
So I retested the unit no luck. I then opened the unit to see if I could fine any fuses maybe blown none was. I then tested the speaker transistors and found one channel was bad so I got another set of Sanken D2390 and Sanken B1560 transistors replaced them both as both was shorted one was shorted Common to Ground and to the Emitter or Collector I dont remember and the other was shorted Emitter to Collector. Retested all was good after. Checked the Bias and reset it to match the other channels.
I put the unit back together and the unit now will power on and stay on until I hook up the audio cable to the input board #7020-06309-101-0 then the unit started going back in to protect mode. I then started to test the voltages and found some I voltage in some places and not in others. On the main board with the main power cord there is (1) 2 VR's on one heatsink and (2) 1 VR's on a small heatsink and another (3) VR not on a heat sink. Then on the other main board that the input boards, and antenna, etc boards plug in to there is another heatsink with (4) 2 VR's on it. So I tested all of the input and output voltages as I listed below (1 to 4).
Help please if can I am lost. Yes it's old but I want to use it to learn and to fix it, I have already got a new one to replace this unit. Thank you all for any help ahead of time!

(1) on heatsink
MC7815CT input 19.998 <> output 12.950
KIA7915PI input neg. 5.530 <> output neg. 0.995

(2) on another small heatsink
MC7805CT input 7.350 <> output 3.728

(3) no heatsink
MC7805CT input 10.810 <> output 4,421

(4) on a heatsink
MC7806CT input 0.549 <> output 0.0310
KIA7906PI input neg. 0.040 <> output neg. 0.001
 

Martaine2005

May 12, 2015
4,952
Joined
May 12, 2015
Messages
4,952
Hi justme,
Have you looked at the service manual?
You seem to have enough knowledge fault find.

Have a read of the manual here.
Might take 5 or 6 seconds to load.

Martin
 

justme1971

Jun 21, 2015
3
Joined
Jun 21, 2015
Messages
3
Hello Martin, Thank you for the link! No I had not yet until now looked at one I had ordered one but it has not yet came. This is great I now can start to trace it better. I have checked the transformer and the output seems okay. I am sure it has to be something small?
 

shrtrnd

Jan 15, 2010
3,876
Joined
Jan 15, 2010
Messages
3,876
I'd get those voltage regulators up to snuff, and then see if you still have a problem.
 

justme1971

Jun 21, 2015
3
Joined
Jun 21, 2015
Messages
3
Thank you Shrtrnd. I am trying as on now yet to find the root of the problem but still looking :confused:
 
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