Harman/Kardon AVR5 reciever problems

[Big Tom]

I was at a local garage sale and picked up this H/K reciever for $10 being it didn't work. What happens is you power the unit on and the display comes on etc, and after a few seconds it just shuts down.

I haven't had time to even open the cover for the unit yet but I'm thinking maybe the outputs have shorted and when the amp is turning on it shorts and shuts off... that's my theory at least I've never played with one of these before


But I was hoping someone out there can get me a link to the repair manual. Any additional input or advice would be appriciated.

Cheers,
Tom

[ifrythings]

It sounds like a shorted channel, though it could be a missing supply line or open resistor (like emitter resistor). Check for DC on the Emitter resistor, you'll probly find close to one of the rails outputting. Also check for the usual suspect, Bad soldering.

[Big Tom]

Well I finally got the thing brought into the shop and cracked open the lid. Nothing obvious, checked the rails after the bridge rectifier and was getting +/- 42V so that seems alright, I tried looking for the Emitter resistor but without taking the whole thing appart I'm not sure I'll have a chance of finding it. Ohmed the outputs and 2 come out into the MegOhms while 3 are around 17Kohms, not sure if that's weird or not.

Basically I'm still hoping and holding out that someone here can get me a schematic and possibly repair manual before I dive in, plus I'd like to snap a few digital pic's so I know how things go back together.


I did find out that if I press MUTE before the relay click that the unit will stay on and I can switch around the inputs and adjust the radio etc, but as soon as I un-mute the unit and the relay trips the thing shuts down. To me, that's saying there is probably a short after the relay, but I could totally be out to lunch.

Anyways, again any tips or hints are appriciated. Remember this is the first reciever I've played with so any help is welcome!

[derguteton]

I will upload it : 20.07.06 - www.sharefx.com

[Big Tom]

Got the service manual! Thanks derguteton for the link

So that's good, I was checking over the schematics and trying to get familar with everything and understand what's going on when one of the guys I work with in the shop takes a peak inside, a min later says "You have a cracked emitter resistor."

Well... don't I feel stupid


ifrythings was pointing me in the right direction the whole time, the 5W 3 pin 0.27ohm resistor is destroyed and there is also a 1/5W 82ohm blown resistor, and a little more testing found the 2SA1695 is dead also, the complimentary 2Sc4468 seems to measure fine but if I can I'll replace it as well.

So, 3 bad parts thus far. Anyone out there know where I can find some replacement parts? The resistor and transistor are going to be somewhat tricky to find without paying alot. I'm debating trying to figure out a way to just run this reciever as a 2 channel instead of all 5, that way I can simply use the good parts from the other channels to make sure simply my right/left outputs work. I'll probably never use this for anything besides a shop reciever anyways, I have a much better home stereo setup already.

[Big Tom]

Well, since I got the service manual for the reciever I've been poking around, like I said above we figured out where the problem was comming from and I've got a few parts on order (nothing like free samples!) but some are proving to be a bit of a PITA to get for pretty much free.

So then I got to thinking... ... this is a 5 channel reciever with 5 seperate amplifiers... so check over the schematic and all the amps inside are a carbon copy of each other... Now this is an older reciever and the only way to get the authentic 5 channel outputs is to hook it up to a DVD player or what have you that has all 6 preamp outs, there are no digital inputs on this reciever.

So basically, for my purposes this reciever is useless as a 5.1 setup since I have a very nice home stereo already, this is going to be used mostly for my office or garage running stereo for the radio or a CD etc, so I really don't need to have all the amps working just the front right and front left, problem is the front right is the one that's blown.

So, doing a little double checking I was able to pull the +/- rails from the F.R. channel so it's dead and shouldn't cause anymore troubles, then bypass the input and go into the surround right amp and then again bypass the output so my right surround goes to the old F.R. channel output. So basically, I completely bypassed the FR amp and wired the SR amp to operate in it's place. Put it all back together, fired it up and it now stays on, hooked it up to a simple source off the comp and both channels work fine!



So for $10CAN I now have a Harman/Kardon stereo amplifier with 2 spare internal amps in case anything happens down the road. And if I ever get the parts in that I need to fix the amps, maybe I'll put it back to a 5.1 setup just for possible resale value.

I'm happy with it!

[Cal Weldon]

Good going Tom, the AVR 5 lives on.

I'll send you my AVR40 is she ever gives up the ghost. They're both nice receivers.

[Big Tom]

Well as far as recievers go I've always been a Denon man, but for the price this one is a bit of a steal. It would be interesting to take this one home and listen to a CD on my Denon for awhile then swap this one in and hear for any differences. I've heard good things about the HK's but this is the first I've got to play with.

The guy I work with was the one who told me about this forum, he's collecting parts to build his own and I think he was eye'in up some of the guts of mine pretty seriously! nice beefy +/-40V transformer, decent heatsink setup...

I got thinking it would be fairly easy to incorperate my own amps into this unit down the road if I wanted, the layout is super simple and I could install my own amps in probably a couple hours and have all the functions of the reciever but with my gear installed!

I have a couple sticks of authentic 2SA1302 and 2SC3281 kicking around... this could be a very fun little cheap toy! Like I said the layout is super simple, basically the whole thing is just a simple switcher that selects which input to shoot to the amps and that's about it, if I build my own amps for inside everything is sitting there ready to go.

[MrGnowitall]

Gotta love the internet.

BigTom, I've got the identical symptoms that you describe with my AVR5. I'd love it if you could shoot me any useful pics/docs that you have on the topic. I've opened it up, but I don't see anything amiss. Everything, down to the mute button, is the same as you describe it.

Although I'd like to fix the channel rather than reroute it, if it's too much of a pain, I'll follow your lead on that one and use it in the basement as a stereo.

Thanks,
Pat

[Big Tom]

Pat,

I have the entire service manual at work I can send you, it's 27meg PDF file though if I recall correctly so we'll have to figure out some way to send it to you. First things first, you might as well measure the emiter resisters and also the 2SA1695 & 2SC4468 to check for any shorts. Now that I know where they are it's pretty easy to get a DMM in there and check especially if you've got everything apart and pulled out the heatsink with amp board attached.

Anyways, keep in touch and we'll try to get yours back up and running! I'm still enjoying mine in the office, get alot of compliments on it to from envious coworkers