ONKYO TX-SR502 RECEIVER "SHORTED CHANNEL REPAIR"

so today we get a yankie receiver on the bench and it is a Akio a br no I'm sorry AV receiver model number TX - sr5 Oh - so you get this focus here there we go and the problem with this receiver is the next-door neighbor asked me to come over and check it out it was wouldn't come out of standby the section circuit hasn't been engaged and I suspected a short an output so what I did was as I took the cover off tested a few components and determined that there was a shortage channel so what I ended up doing just to get the receiver up and run until the the parts came in was I clipped the bad transistor out of circuit and I was able to revive the receiver out of standby and we used it for a little while until the parts come in and here it is so the parts are here and I'm going to try and get the the old ones out so what you want to look for here I got my multimeter I'm going to put it on on ohms and see if I can do this from these one on the camera but you're going to check for usually when these transistors show it is usually a pair per channel and what happened is these two transistors right here it showed it out be the one by you know should it speak a terminal or this noble resistor shorted out or opened up actually it didn't probably won't show up probably open so what I did was that first check the mobile resistor it should be relatively low level stuff like a show it's a point one 0.01 something like that so two point no it's point point two to home so it says on the side so if I can try and get my me around what's going on you'll see that it's a floating around it's 20 K something that's definitely opened up if you come over here to the other side there we go one ohm so yeah she's no good she's opened up and what happens when that opens up is usually these transistors that are hooked into of the emitters usually show it out and that's when then it throws these receiver into standby and you won't be able to get out of it so we're going to do is we're going to pull this resistor out and pull these two transistors and make sure everything else is okay in circuit and put new parts in and we'll see what happens all right so for replacement parts we get a a noble like resistor it is basically two resistors in one clearly shown here 51.2 to ohms now because of the resistant flankton way it gets we're going to get a discrepancy of 0.9 ohms to 1 ohm so I'm going to check the new part and the way these are hooked up is is one resistor from the center pin to the left pin and one resistor from the center pin to the right pin and each one's should be 0.2 2 ohms if you have you immediately zero it out and if your meter need an arc you can't zero your me leads out you can subtract the value from when you short the leads together like we had they have point nine one ohm so we're gonna try put this up like this so we got 1.1 all alright so yeah good in the other side 1.1 okay good so - 1 ohm would be point 1 point 2 so okay this is a good new resistor and same thing when you check into the bad one you're going to apply the same zeroing technique on your Vita leads so and for the audio power amps we have cross-referenced a B eight one seven which crop pressed references to a 1937 there in 237 and the other one was a d-104 7 which crock references to a MTE 36 so if you can't get original parts and te will work just fine because that's all you can get that's all you get so we're going to try and get these parts in there and see what happens I'm going to check some of the pre drive a circuit to make sure there's no shorts or any open circuits and anything and before I go firing this thing off and we're going to make sure that the we're going to put new compound in one behind these transistors also and we're going to see what kind of installations behind there if there's a some micro insulators flecked around new packaging you'll notice that there's a glass looking piece very fragile you don't want to bend this stuff it will crack a fracture so we'll see if what we can do if the old ones look good we might just put those back in so we'll see what happens first I'm going to try and determine how I'm going to get this board out because there's no access panel on the bottom of this receiver so it looks like a lot of stuff has to come apart to get access to the side of side of this bottom lower board where all the transistors are soldered to so we'll come back when we determine how we're going to do that in Miri be all set to go and we will start soldering all right so we're going to try and do is we're going to try and we'll pull up the fuel train systems which I've already marked about the heatsink which ones they have the set of three the set of three and we're going to pull the noble out which is these three points right here and so what we're going to do is when I use my desolder and go start taking them up sometimes you need a little solder to get it static and sometimes there's no fluff now you can use the soldering braid solder suckers whatever you want I just like showing off my new toy all right so sometimes the needs their little stock I need my then we'll just use this and we will get it later and I wouldn't fell behind but we'll get it and now we'll take the hey get rid of these pieces now we'll take up the noble that's that that's the old one now we'll put in the we have to bend the leaves a little bit so they don't fall out on you when you hit them with the solder it's always fun all right that piece is in now it's not to do is take out the old transistors on from the off the heatsink has already cut the leads so put new transistors on will fold those new needs over and soldering back down to where they belong and so now we're going to take out the two transistors that were cloaked originally very cheerfully pop them off the heatsink there because it's going to be a micro pad behind it sometimes you're going to slide them up they'll come right off there's no good we're going to and check those I'm sure they did No let's go down check those transistors to make sure I'm pretty sure they did I'm going to put these things on dead short that short dead short dead short so you know what these are going in the garbage that's not too bad they cool stickers on now so let's put the new parts what are they doing so the MT 36 left brand-new pot I'm gonna do is with them put some new goo on their sweet compound I don't go too crazy just a thin layer a little rubbing with your finger so you need we'll get down tight but don't don't go crazy try to get this thing super super tight just enough to snug it up same thing the yellow one try to get the transistors as straight as possible to it'll help you when you saw the pins on the backside all right so we've got the two new transistors and right there there now we're going to flip the board over and solve those bad larry's in yeah flip it over have fun missus now you see me going sticking up in the bar what I do here is I'll fold them over spec get a better tool for that was my trust don't trust e-ring this rude okay I want to take a regular solder the other side when I tie those pots down that's in there nice so just clean the clocks up again a little alcohol on a toothbrush very good actually looks cleaner than the manufacturer surah so now what I'm going to do is I'm also going to check the biasing pod make sure it's close to the others or not damaged because that sometimes be a problem to the bias pawn is right here let make sure it's so that looks like it's a 1k f1k yep 286 close enough so we want to see circuit that's one side to the end it's open open circuit so that's what caused the failure probably even though number one that I said before the Transit Center shorted or the resistor had opened up one of the two okay so now it's just pretty much reassembling I'm not going to bore you with that so we'll come back when it's all back together alright we get everything fastened back downing the transistors are in the new mobile resistor is in and got it plugged in we're going to turn it on and hopefully it comes out of standby and it lets a turn on okay so it does so I think this is a win so we are going to check this out before I give it back to the room and make sure everything's working breath diet everything went well and it was relatively not too bad other than taking this thing apart which was kind of a bear but it wasn't too bad so that's how you can fix a a dead Channel on your rock hold receiver hopefully this helps us simplify things and get you up and running good luck

Channel: The Active Region

Views: 227,732

Rating: 4.6706829 out of 5

Keywords: ONKYO, TXSR502, RECEIVER, NOT WORKING, REPAIR, ONKYO REPAIR

Id: DKCSD3F3D9w

Length: 24min 2sec (1442 seconds)

Published: Fri Jan 11 2013