Harman/Kardon AVR130 Repair - Ec-Projects

hello and welcome to these projects today a lot that's around Ziva it decided to fail yesterday a little poof and then now it's nothing on the outputs but it seems to pop just fine and it recognizes to the incoming segments so I try plugging in the headphones and they're playing alright but I'll speak output seems to be dead so let's try to take off the call and see what's going on inside so to get an overview of this unit we can start with the mains input go into this vault and into the transformer here we have their secondary windings in these two box some regulators a small transformer down on the bottom bolt with some some more regulators we have what looks like a video input output port and a tuner digital board and the main amplifier board is down in the bottom and there's also a LCD and volume control board on the front here so I have thought to look for any loose connections or visual defects but I can't seem to find any at the moment oops that one looks like it's blown yep we have a blown fuse so let's try to replace this and see what happens and we can soon make a collection of these I think so the blown fuse was found in this bar over here and it sits directly on the secondary winding of the transformer so that will it seems like something is shorted up so well let's try to measure the resistance from that fuse to ground I found that these two notes here will be what we're looking for and you can see is it's a dead show finding a shot like that may not be as easy as it sounds because it could be anywhere on any of these bolts so we can try to unplug the bolts systematically and and see if this shorten disappear and the output from the fuse goes through this bridge rectifier and it goes into this connector so you can try to unplug this and we can try to measure these pins and see if we still have let's shorten it and yep it's still solid soon at least we can sell that this ball should be fine and then the short should be located this watch somewhere but I think it's time to dig out the service manual for this thing if we can find anything online so I have find the schematic in the service manual and the fuse that is blown is this one over here legacy it goes for the connector we measured here and it goes to the main board and on the main board it is this note here called plus VCC and it turns out this is the it's an unregulated supply ring for the amplifiers and this means that the short could be anywhere on the board actually this VCC powers free of the amplifiers and the VCC one powers the other two amplifiers or the shoulders between plus VCC and ground I've also check the - mrs. C - ground and it's measuring and the killer own swimming so it should be fine we have these two caps between plus VCC ground and minus VCC so it could be something with this capital here but it could of course be anywhere on the board VCC goes into this bus line here and did PS seven or eight times around the bottom plenty of things to check for sure if we take a quick look at one of the amplifier channels that gets powered from VC see it does not seem that if any of if any one of these devices would fail that there will be a direct shot between the two rounds the only true ground connection is is over here and this one here I have tried to follow the traces around and it seems that there should be some resistance even if one of the devices feel dead sure but then we also have a capacitor here in the mute section that sits between ground and VCC so this would also be a potential issue so it does seem like those two capacitors would be the only way a single device could fail and make a short between the rails but of course could be multiple devices that have failed but didn't sound like that and since it didn't seem like any of these ports gets powered from the VCC rail and I will try to remove those so we can get those two capacitance so by undoing a few screws in the back and unplugging these two connectors we can check out this video Bolton and again the VCC railed it that seems to go to this porch so I'm pretty sure that this would be all fine and the same for this radio tuner board and if I'm not mistaken this sport will do the digital processing of the signal and do the digital to analog conversion it seems like the analog signals will go to the amplifier board while this connect the ball over here then about 20 screws and the few connectors data we can remove this city to the wall as well oops let's cable-tied there we go so I finally got this amplifier bolt out and therefore stopped probing around and I found that the this capacitor in the mute section actually has a series resistor so it cannot be that one but I did also find that the lowest resistance between VCC and ground is around this capacitor here so I think I'll try to desolder that and remove it and try to see if and that solves the problem I forgot to record this but it's this capacitor sitting here this one capacity of each rail and this was the positive reasons for the negative and this is for the other two rails these two around here smaller because they only have to power two of the channels while these power the other regions and I also forgot to record the part where I measured the circuit so I have s soldered in a component lead here to simulate the capacitor when it was in there so I just measured from where the ground leadings as the circuit here and start probing the the raising VCC rail I started with these powertrain systems and just went around here you can see the resistance is decreasing so that would mean we're getting closer to where this yard is if we go up here should and gets a number gets larger again and then measured this something around here and then the resistance is getting lower as I get close to this bed capacitor here so I I finally measured directly across this I can see the resistance is a little low when they're measuring something like this is almost essentials I have a multimedia that have at least three or four digits after the decimal place so you can see even small changes in resistance we have to be very consistent in your measurement and then if I measure this really if I press a little harder than Z it decreases in evolution it increases if you have to be very consistent in the amount of pressure you put on this it has the difference in the resistances very small and with the capacitor remove we now have 5.1 K ohm instead of 0.06 so I'll bet you that when we when we measure this capacitor it's it's a dead short yep we have a winner Oh a loser I should say so one fortune they don't have any of those latch capacitors but we would have to buy some and I think I replace our fourth because the next might be as bad as this one so it could fail in love there we go - so I don't want to take all this apart again and just a little detail I couldn't find half of the new power transistors I think I know why because they just sit under the heatsink it's a little funny how they just soldered directly to the traces there's actually a few patches yes and there's also a budget in a transistor done it's just flying in free and looks like and there oops that's another one capacitor you you so while the caps have been removed and they're the new ones have turned up so inside star illusion so this blue one is the new cap and of course the black one is the old one but one thing I don't understand it's why on earth they would use 85° caps in a in a receiver that gets very warm inside I bought some 105° caps and hopefully they will last a little longer so let's get these in place and see if it comes back to life you and just to check that everything is in order yep that seems fine oops yeah you you so it's all back together and then let's try to power it up and see if it works that's it and then that's just an AM radio noise but then see if I gets back up and running so one of the travel for just one bad capacitor well I hope you liked it in there thanks for watching and then please give it a thumbs up if you like to see more of these repair videos and of course you're always welcome to subscribe to my channel if you're like let's see

Channel: EcProjects

Views: 96,685

Rating: 4.9073868 out of 5

Keywords: Harman, Kardon, Harman Kardon (Organization), AVR130, electronics, Ec-Projects, Repair, Fluke 8846a

Id: at7GLypcLro

Length: 17min 23sec (1043 seconds)

Published: Wed Mar 27 2013