Harman Kardon AVR 20II Repair (pics)

[Alex2507]

Yesterday I got this for $20. Plugging it in turned the power button red.
Pressing power button turned it green for a few seconds. Then back to red.
A fuse labeled NB5A125V (short glass job) is blown.
Two resistors have leads that either corroded or burned off.
No burn marks but there was a green/white dust covering the area.
They are on a PCB attached to the volume control.
A link to a real service manual and a color code translation would help.
Pic's as promised. Thanks for stopping by.

Help me be the biggest geek I can be.

 

[Alex2507]

I got that little PCD unhooked and out by the window for some shots in better light.

Those resistors are tiny. 3/16" for the body.
You can see a little blackened area under them and under the caps.
It's only clear in the middle because I ran my finger across it to be able to see.
The camera actually helps me see this stuff. It's pretty small.

 

[Adam]

I haven't found a free service manual, yet, but you could be the man by ordering this and hooking us up. Only $15 for a large number of Harmon Kardon service manuals.

 

[Alex2507]

This guy http://forums.audioholics.com/forums/member.php?u=9463 had links to all sorts of H/K service manuals. I haven't done a thorough search to find the link. Good thing he's not like me. I posted something useful twice in 4,000 posts. Good luck finding it. The manual isn't that important. I can physically see what's fried but there may be something further up the line that fried it.

I'm going to get my soldering iron out and remove the resistors. Radio Shack might have them. When I grow up I wanna be TLS, except for the old part. Highfigh, Markw, T2T, jinjuku, Hi Ho, Haleob, WmAx, Swerd and Lordoftherings (Bob?) are all invited to chime in. Don't make me PM you because I will.

That's just the guys I can think of off the top of my head that are particularly impressive with this kind of stuff. I'm sure there are more.

 

[bandphan]

I'm going to get my soldering iron out and remove the resistors. Radio Shack might have them. When I grow up I wanna be TLS, except for the old part. Highfigh, Markw, T2T, jinjuku, Hi Ho, Haleob, WmAx, Swerd and Lordoftherings (Bob?) are all invited to chime in. Don't make me PM you because I will.

Thanks know I know how the dog feels.....

 

[Alex2507]

Google leads me to believe that they are 1,000 Ohm resistors with a 5% tolerance. Wonderbread's manuals don't include this one. I may need to email him but I am pretty laxed out ATM.

 

[Alex2507]

Thanks know I know how the dog feels.....

You and annunaki are the TV guys to me. I didn't have you pegged as a resistor reading solderer, more like a remote programming calibration guru but jump right in. The water is fine.

 

[Alex2507]

I haven't found a free service manual, yet, but you could be the man by ordering this and hooking us up. Only $15 for a large number of Harmon Kardon service manuals.

I just ordered it.

 

[bandphan]

t jump right in. The water is fine.

Thats not a Jacuzzi, where are the bubbles comming from

Ill have the service manual for ya with in 24hrs... I use to own this unit and it was very nice, it was a pre to my mac but I did use it drive some TL DCMs when I had the face plate of the mac was being replaced and was quite impressive



EDIT too Late sorry

 

[Alex2507]

Hi Scott,

The disc I ordered is coming from the Netherlands so your manual would be a help. How would you get it anyway? Special Installer Manual Connection?

Thanks,
Alex

Edit: I'm surprised that you had this unit. It's old enough not to have DD and is only 60 watts/ch in stereo. I just noticed that it has left and right sub outs. I can only hope it will allow me to EQ a stereo signal and then apply the rec'r's xo while maintaining stereo sub outs instead of being just dual mono. I just used the Ohm meter to establish that the centers of the jacks are in fact not connected.

My friend has one of these. I hooked it up to power his passive sub but it was completely put to shame in that capacity by a Peavy pro amp. Still, for my needs this would be wonderful and as it is has already provided me with $20 worth of entertainment.

 

[highfigh]

Yesterday I got this for $20. Plugging it in turned the power button red.
Pressing power button turned it green for a few seconds. Then back to red.
A fuse labeled NB5A125V (short glass job) is blown.
Two resistors have leads that either corroded or burned off.
No burn marks but there was a green/white dust covering the area.
They are on a PCB attached to the volume control.
A link to a real service manual and a color code translation would help.
Pic's as promised. Thanks for stopping by.

Help me be the biggest geek I can be.

I hate to rain on your parade but that looks like water damage and if that's the case, you may never get it to be reliable. Even after re-soldering every joint, it may not last.

 

[jamie2112]

I hate to say it Alex I agree with highfigh it looks like water damage or liquid damage of some kind......but hey its a project right?

 

[Haoleb]

It actually doesnt look too bad. Ive seen similar a few times. The best thing to do will be to write down the values of the parts that are there and their position (R625, C617 etc) and then desolder them. Note that the schematics do not always match what is actually in the unit. Clean the circuit board I use isoprophyl alcohol or just water and a small toothbrush or paint brush and then rinse off using distilled water (in this case you probably dont need to worry about it) and simply re solder in the new parts and see what happens.

There is probably something else wrong with it because I doubt that what you see on the volume control board will cause it not to turn on. I would check the dc offset and bias along with replace all the electrolytic capacitors and any other parts that look corroded.

 

[Alex2507]

Even after re-soldering every joint, it may not last.

Only one way to find out.

..but hey its a project right?

Right? Right? Right?
Right.
Right.
Right.

I'm out of my head!

Got me a parts list and I'm off to the Shack so I can stay up half the f^%&ing night trying to figure out this useless piece of f^%&ing sh!t.
~Remember the bit on the Onion?~
No? Trust me, it was hilarious.

Sometimes I experiment in the kitchen and the whole kit and kabudle ends up in the trash, pot included. I'm hoping for better results here. I'm going to replace a couple of other resistors that were swamped in and hope for the best.

 

[jamie2112]

Go Alex go..........

 

[Alex2507]

There is probably something else wrong with it because I doubt that what you see on the volume control board will cause it not to turn on. I would check the dc offset and bias along with replace all the electrolytic capacitors and any other parts that look corroded.

I kind of polluted this thread with a million of my own posts so it's hard to find stuff but a fuse is blown and I just saw a ceramic block type resistor leaned over and perhaps it's lead was touching another one.

I don't know what a DC offset is. Dude, look at my avatar. I'm a chimp.

 

[jamie2112]

Tooo funny Alex........

 

[Haoleb]

Do you at least have a multimeter? Not much you can do without one of those.

 

[Alex2507]

Do you at least have a multimeter? Not much you can do without one of those.

I'm a chimp, not a gorilla.
I have two multi meters. One is an amprobe.
Knowing how to use it is another matter.
I have my parts list and absolutely have to run to RS before they close but when I get back I would some guidance on things to check. Cool, in Hawaii it's early. This could take all night for me.

Back soon.

 

[Alex2507]

Operational Head Quarters

I let the girl give me the wrong resistors for the ones I wanted to swap out but she gave me the right ones for the ones that were burned out. Also they had the fuse that I have to replace but not the fuses that I want to replace. I'm ready to fire up the iron and have another pic boys and girls.

BTW, the resistors that Haoleb suggested to change out and that I wanted to change out but I got the wrong parts for actually do ohm out within 5% of the 470 ohm spec so I'm gonna go with it.

Doug may be onto something calling me a geek.
The real geeks are thinking 'wanna-be'.