. . . Sourcing replacement power supply circuiit Capacitor in NAD 7600 Receiver

inspiredsports

Twinkle, twinkle little star?

Nope, it was the top edge of a green (ceramic?) cap in the power supply circuit of my favorite receiver (1988 NAD 7600) during a loud late-night listening session on a rare night when the wife and kids were all away.

The insulation at the top edge of the cap (about the diameter and thickness of a dime) is burned away and the tiny guts inside started twinkling just before I leaped across the room to shut it down.

Any tips on sourcing a pair of these?

Photos next post below:

inspiredsports

billbillw

Find the service manual, look up the voltage and capacitance. Search at Mouser or DigiKey. Doesn't have to look the same. Just try to get the lead spacing close. Probably a good idea to recap the whole power supply while you are in there, especially the smaller ones. For a receiver, I'd find ones that are 105C rated to 10000 hours.

Edit: If you haven't found it, here is where you can find the SM.
http://www.hifiengine.com/manual_library/nad/7600.shtml

billbillw

Ok, I had a minute and had a quick look at the SM. Those aren't capacitors. They are positive temperature coefficient devices (PTC...other wise known as re-settable PolySwitch). Much like the ones in some Polk SDA speakers, they go bad after ~25 years. You could probably just put a jumper in its place.
Or, buy a couple of these and change out both:
http://www.digikey.com/product-detail/en/RUEF185/RUEF185-ND/1045786

Looks like that receiver has 3 power supply boards. (The one with the big caps, and the two vertical boards next to it)
I'd probably replace all of the small value electrolytic caps while you are at it. They are all probably getting to the end of their life. The 4 big caps are probably OK, but you might want to change those too if you can find suitable replacements. For just the small caps, I think you are looking at less than 15 caps total. The smaller ones are pretty inexpensive so it would probably be less than $30 for all of them.

inspiredsports

Thanks Bill,

Wayne at Stereo Repair / In House Service Company recapped this unit for me in 2011. I guess replacing these weren't on his to do list. I'm just going to bypass and I sure appreciate the help!

Greg

inspiredsports

Bill, Thanks again for the insight!

I just got a chance to clip out and bypass those thermistors, and my 7600 is pumping out anything my modded SRS 2's ask of it. It'll be a sad day around here if it ever really dies.