Protection Light Behaviour

[Tinnkindling]

I have a question about the behaviour of the protection lamp LED on my AU-20000. When I turn on the unit, the LED shows red. After a few seconds, it goes out. On my BA-2000 and BA-5000 units, the lamp goes on red, then turns green.

Can someone with an AU-20000 take a look at the lamp, and tell me what transpires when their unit is switched on, please.

 

[Hyperion]

Not sure about the AU-20000, the other 2 have a dual colour LED (back to back colour LED) which is made to 'see' different polarity voltage depending on the protection state.

Seems like you may have a minor protection board fault?

 

[craggd]

I think that is the normal operation, my AU-20000 is the same (red to off, no green)

 

[Tinnkindling]

Thanks for the replies, my mind is once again at ease! I have to remind myself why I bought this gear in the first place, and that was NOT to look at the lights on the face plate, but to enjoy the music...well, mostly.

 

[JOMARK911]

Well Rick , looking at those fabulous face plates is indeed a part of the enjoyment of the music. The optical part let's say.

 

[JOMARK911]

I'm not sure if you put a double led in there, like BA 3000 has, if will work the same.Red then green.

 

[EchoWars]

TR05 on the F-2511 board takes the anode of the front panel LED to ground as soon as the speaker relay is engaged, turning it off. If the protection finds a fault and opens the relay, the LED will light, letting you know that there's a problem (if you hadn't deduced that for yourself already).

Some other Sansui gear has a dual color LED. I can't remember which kind, and too lazy to look it up, but...

1. Some two-lead LED's are designed to show one color when forward-biased one direction, and another color when reversed.
2. Other dual-color LED are three-lead devices with a common cathode...forward bias one anode for one color, and forward bias the other anode for the other color.

 

[Hyperion]

I just double checked, BA-2000 and BA-5000 protection LED's are both back to back 2 colour LED's - i.e. number one above.

 

[EchoWars]

Well, you'd call them 'anti-parallel'.

 

[Tinnkindling]

I just double checked, BA-2000 and BA-5000 protection LED's are both back to back 2 colour LED's - i.e. number one above.

And what did the source say for the AU-20000? Just kidding ;-)

 

[craggd]

I do find it interesting to see the difference in the protection light protocol between the AU-20000 and the BA-3000. Would think both being in the same build era (early-mid 70's), high end units and with the shared power amp they would have the same. Maybe the difference between the Definiton and Professional Series?