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
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
