DENON AVR-X4300H BLINKING RED LIGHT OF DEATH AMPLIFIER REPAIR

so I didn't bring you along at first but now I want to show you a couple things on this dead-on in command series integrated network a via receiver AV R X 4300 look at all the stuff that's inside this guy so it's got one power amplifier board right here it has another power amplifier board right here and if you look down here you'll see a couple of fans because it's probably gonna need them for each channel that's a very small heatsink and then we've got all the digital processing right back here alright look at all those chips on that board over here the power supply of the power transformer underneath there probably hard to see a couple of big filter caps and then over here if you look right down in though right down in there you'll see a bunch of regulators there's probably six of them leaning up back in there anyhow what this thing does so I've got the blinking red light of death when I press the power button it goes completely solid red the next press I get blinking white light continuing blinking white light and then shutdown in red blinks again so looking at the display AV surround cable Santa stereo display goes blank and then the power goes off and I get the blinky blink red once again okay so one of the things I see right off the bat is look at that resistor that's a low value resistor to two points out then maybe 22 ohms looks like red red black but look right in the middle of that you'll see a big melt spot trying to move the light around so you can get a better view at it but that looks bad take a look at this one this is the sister to the other one and I clearly see a red band and an orange band in the black as I'm moving the lighter I hear appears that it has a burn spot on it so I'm thinking the first order of business is to pull the power amplifier board out of this unit and will actually take a look at those resistors and see if they're bad or not so I'm thinking it may not be that bad to get the power amplifier board out of this unit it looks like I can remove these two ribbon cables and they're both going to just fold out every major lead on this unit either is plugged into another board or very hard to see but that white connector with the red lead in it right there it's plugged onto this board there's one just like it that you probably can't see right in here and so I'm thinking if I just pull the screws out of the power amplifier unit and unplug everything else it was just simply lift out of the unit all right well it was just as easy as unplugging these connectors moving the ribbon cables up out of the way the white connectors go on this far facing side of the board and the red connectors go on this face of the board so there are several of them all right well I've got the board up here in slightly better lighting and if you look at that resistor you can definitely see a defect as well as that one right there now all the rest of them look absolutely fine except for baby maybe being mangled okay so I've got my voltmeter in the 600 ohm range because I'm going to be measuring 22 ohm resistors on short that leads out lead integrity is about three tenths of an ohm and so I'm just gonna go ahead and test one of these over here there's a known-good resistor and we'll see 22 point 2 ohms which is absolutely perfect one of the bad resistors right here I get thirty point two ohms and then the other one right here it is open let's put it back in auto range Wow not even on the mega ohm scale do I get anything at all for the heck of it let's go ahead and check the emitter resistors which are these large point four seven ohm resistors so it should come up to pretty close to zero and that one's open that one's open open open okay so over here is a known good Channel and I see point five these are in parallel so they better both read the same yes okay so I know we've got open driver resistors and open emitter resistors so here's the output transistors it's easy enough just to put this on the diode range and we'll just measure these transistors that one is shorted collector emitter what's interesting is base to collector emitter is not shorted right now nothing on reverse polarity so the base is still fine I'll check this one let's change the leads that one's a dead short so we're going to have to pull this board off to be able to get these output transistors this is a bias current regulating transistor which is why it's on the heatsink so with transistors as they heat up and cool down their gain changes ever so slightly and with this type of amplifier you want to keep each transistor barely biased on so I think it'll be pretty easy we can gain access to all the power transistor screws right through these holes here and then it's got a couple of other screws and so I don't have to take a nun solder every single one of these transistors if we can go ahead and pull the majority of them off the board well they certainly came off easy they seemed to have adequate heat sinking compound on them well let's go ahead and get those two bad ones unsoldered off the board and what we get to the bottom of it and it's got some drivers and pre drivers and whatnot we're gonna want to check those as well I have the meter on the diode arranged I should get a solid tone okay so all I really care about is whether it's shorted or not so I'm gonna check collector emitter and just go down the line we may see diodes we may see resistances those are the two bad ones so those all check good just for the heck of it we'll go ahead and check the bias tracking transistor yeah I'll check about the same so all the 590 something range yeah even that one okay so let's go ahead and get these transistors unsoldered off the board so we can get access back here and check some of these other small components [Music] all right so anytime I pull a transistor off of one of these boards I'm going to take a look at the number whether it's a 2's a B C or D and I'm going to make a note somewhere on the board the corresponds to which transistor goes where now we can get them back in the right place when we get their replacements so for sure we know that these guys are bad that's a dead short that's a dead short so let's move those out of the way we'll go ahead and quickly test this bias tracking transistor I see a junction there I see a junction there and I don't see a short here which is good so I'm gonna call that one good all right well I did manage to find a schematic on this unit even though it was made in 2016 and so here are the two output transistors q70 131 that's the two SD 2560 and q70 132 that's the two sb 1647 now this is the idling current bias transistor right here the one that we tested and it was actually it tested good I'm a bit concerned because the base which may have taken a small amount of current it it had to burn up these two resistors right here so we had to have some current feeding back here to burn up these resistors one much more so than the other one and so really the only path this has to go is across this transistor and to the other output transistor because we're limited here by a 2.7 k resistor that says it's open yeah we're into another small transistor these are the two driver transistors will test those just to see what they test like they're actually slightly larger transistors on the other side of the board so let's just go ahead and test those right now once again I'm in the diode range hopefully I won't get in the way of seeing the meter good Junction good Junction and good all right good Junction good Junction and open it's exactly what I wanted to see so it looks like the driver transistors are actually okay so usually when that happens that means everything from here back is just fine it does look like if you look very closely here these are the emitter resistors where they soldered at the board this channel is darker than any of the other channels some wondered if he was having an overloading problem for quite some time on this unit which would cause these emitter resistors to get fairly warm I'll have to question about that so it looks like at this point we just need a couple of output transistors and I probably go ahead and replace that bias current tracking transistor at the same time all right so I have AC 39 64 AD 25 60 Abby 1647 a couple of 22 ohm flameproof resistors and for 0.47 ohm 2 watt emitter resistors so we'll go ahead and install those on the board and see if we can get this unit to power up and stay on and make sound okay so I have the new resistors the 22 ohm resistors and the 0.47 ohm emitter resistors installed on the board now I'm not going to go ahead and install the transistors of this time I want to go ahead and put those on the heatsink first to make sure that they match with the board correctly and cuz I have been the lead slightly I don't want any extra stress on the circuit board so I'll mount those to the heatsink mount the rest of the transistors and then bend the leads as necessary and then solder them to the bottom side of the board over here okay so I have the two power transistors and the bias regulator transistor mattered to the heatsink right now I've got the leads just kind of tentatively bent up as necessary I've got fresh compound on them next I'm going to go ahead and mount the board and we'll mount all the rest of the other power transistors at the same time all right now I'll go ahead and solder a man all right that looks good they're all mounted let's go ahead and put it back on the unit now and we'll fire it up and see if we get better results okay all back together power is restored let's hit the power button and there it is up and run it so I'm gonna let it run for a few minutes and then it will go ahead and adjust the idling current the bias current for the transistors we'll go ahead and check the rest of the channels make sure they're okay as well okay so the service manual tells me I'm supposed to adjust the bias for 8 millivolts so let's go ahead and adjust all the channels right now actually says eight plus or minus two millivolts so 7.8 that's pretty good that was perfect okay I think that's close enough so it's been running now for about twenty or thirty minutes to let it get good and up to temperature you're supposed to check it within a couple of minutes and then again after 20 minutes of runtime it's working perfectly fine so I think it's gonna be ready to reassemble and ship back to the customer all right so it's all back together it's got audio I'm not playing any copyright free audio so I'm not gonna turn it up but it's up and running it powers up idling Curren adjusted everything's good hopefully the customer will be good now I did ask the customer to bring in the speaker that was connected to the front left and that's the channel that was blown out so we'll probably see a video on testing the speaker if not repairing the speaker anyhow all wrapped up ready to go I want to give us sincere thank you to all those who have supported my channel with the donation via PayPal or having me repair your unit if you enjoyed this video please consider subscribing to my channel and liking this video it really helps my channel grow you can follow me on social media Facebook Instagram Twitter at NorCal seven one five you could also shoot me an email NorCal seven one five videos at gmail.com go ahead and leave me a comment a question a concern down below I'm trying to read all the comments and respond when I certainly have time remember with your help we can try to keep these things out of the landfill out of the recycle bin and out of the e-waste facility everybody have a great day thanks for watching one's gonna really appreciate it bye bye

Channel: NorCal715

Views: 43,441

Keywords: denon, avr-x4300h, avr, 4300, x4300, x4300h, 4300h, blinking red light, wont stay on, powers down, repair, fix, vintage stereo repair, transistor, resistor, driver, amp, amplifier, dead

Id: W2LkHsLY00U

Length: 16min 2sec (962 seconds)

Published: Mon Jul 06 2020