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Relays, Capacitors, and Blown Speakers

OK, so I just picked up a used NAD 2400PE, a 100W circa 1990, because I love the sound of my old 7225PE receiver from the same era. After doing a bit of research on this particular amp, I see that it and its 2000-series brethren were prone to speaker relays going bad. In addition, the amp and its original caps are 20 years old. My question is, when a speaker relay, output, or large cap malfunctions, is the speaker automatically in mortal danger from DC or something else? This particular model has 40,000uF in its supply, BTW. Any input would be much appreciated and help allay my fear of using the amp w/good speakers.
bojack

Showing 2 responses by magfan

magfan
1,583 posts
 
find and read the thread.....it's here somewhere, the subject of which is caps and cap aging. Lifetime is addressed. Please read that carefully.

Speaker relay? I don't see how that part going South could damage speakers. They just won't turn ON. ...... OTOH, if the relay fails latched ON, you could get a startup pulse of DC to the speakers which could damage them.
Relays, being mechanical, are somewhat failure prone. In a 20 year old piece? If it is socketed, just replace it. Hardwired? ask a tech for cost. I'm honestly not sure how much damage such startup pulse could do to speakers, but it couldn't be good....just how bad?
magfan
1,583 posts
 
Right you are, Metro.
Their is also a class of part called 'time delay relay' which is internally controlled to enable the circuit a given amount of time after receiving the 'on' command.
These also fail and will sometimes latch in either open or closed conditions.

years ago I had a special set of files used for dressing relay contacts which had stuck or 'fused', as Metro ref's.
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