Vintage HK protect mode?

There were some Harman Kardon amps that went into protection mode if the preamp was giving some DC to its inputs. I can't remember model, or how many years back I heard about this. Maybe trying another preamp (no preamp if you feel safe) to see if this can be a problem. I can't remember if this happened right at start-up, or after the delay (few seconds?) turned the amp on, then went into protection.

OK. Thanks. I can't get back to you yet because I don't have the amp yet. It is being shipped. But this is very helpful.

It is just possible you are talking about a discrete 'time delay relay' which best case, is socket mounted.

OK. I'm making a list. Thanks. I'll ask a dumb question just to illiminate it: The only info I've been able to glean from the net is that, while build construction was high quality on Citations 22 and 24, the bias settings were all over the map so that quality control was an issue in this respect. Some were set so high that when the amp was driven hard, it burned up. Could a bias set way too high tell protect mode that it was too hot to turn on?

In general, I'd say NO. Not too hot, since when turned on, it's stone cold.

Too high a bias? Don't know if that could trip some protection circuit. Maybe if the circuit 'interprets' that as a short? That'd do it.

In any event, a trip to a tech is indicated. Choices are stuff like bias adjust, or time delay relay problem. Weak output device, going bad? Don't know.
Such relays are fairly reliable, but also a moving part....That click you ordinarily hear is the relay 'flipping'. which means it can wear out.