SSlmixed.com Forum
Tech discussion => 4K,6K,8K Series => Topic started by: gertius on December 13, 2018, 06:52:55 PM
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Hi guys,
can you please help me identify a part of the SSL 82e10 dynamics board?
It is in the position D27, according to the schematic it´s an AAZ17 Germanium diode.
Problem is, all the AAZ17 I find in the net look really different to this part.
They either are totally black, with AAZ17 printed on, or are a transparent glass cylinder.
Is this also an AAZ17 or some sort of replacement type?
I am attaching pics of the part, zoomed in, and of the whole card (part is on top right).
Thanks!
Christian
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Germanium diode AAZ 17 - 75V 140mA 300NS 10 - 0.85
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Hi Pascal,
thanks for your reply!
Do you know the part (by the looks) or did you get it from the schematic?
My question boils down to this: is my pictured part really an AAZ17 or maybe something else?
Did you see it in that optical appearance on other SSL boards?
Thanks!
Christian
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Of the 3 spare 10 cards I have, one has a diode marked AAZ17, one has the diode looking like yours and measures the same as the first one.
The third card doesn't have the diode at all!
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This helps me a lot. Thanks Kevin!
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The type of that diode is important, not the voltage / current rating so much as the "curve" the diode gives to the dynamics response. It wasn't fitted to the very early 10 cards, it was added sometime around 1980? It was certainly there by 1984.
So the main thing is that it needs to be a germanium diode, not a schottky. That said, I think on the 9k I did use a schottky because we couldn't buy germaniums any more.
They may well have changed case style, and I vaguely remember I changed the type of diode in the late 80s because the AAZ17s became obsolete?? We wouldn't have bothered updating the circuit diagram for that.
Basically if you need to replace them try to find AAZ17s if you can.
The glass case was a PITA. If you try adjusting up the dynamics card presets under (for example) fluorescent lights you find it behaves very strangely, those diodes are light sensitive. I remember trying to set up a 4k with the 611s on extender cards inside a BBC mobile studio (one of only two studio installations we ever did ourselves) and it took me ages to work out why when I put them back in the desk the dynamics were out of cal again...
Cheers,
Andy
EDIT: I've just found my 9k circuits, and I did use an AAZ17. So I guess should be that in all 10 cards as well. But different manufacturers may well have used different case styles, we really struggled to buy these so would have changed manufacturer occasionally.
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Seems like the AAZ17 is a relatively long recovery (350nS) diode. The only sub I could find was AAZ15.
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Thank you Andy and Pascal for your replies!
Andy, the background info you´ve given seems to be spot on.
I have in the meantime compared AAZ17 vs AA133 (those I have in another card), and the sound output is the same.
So it really seems that only the type of diode is important, but not so much the voltage/current rating.
Cheers!
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You can try :
https://www.littlediode.com/components/CV7127.html
https://www.ebay.fr/itm/153295425873
Cheers,
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Seems like the AAZ17 is a relatively long recovery (350nS) diode. The only sub I could find was AAZ15.
I can't see that causing a problem! Many thanks for the suggestion.
(And Hi Pascal, nice to hear from you again! :) )
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Maybe this can help if you only need a few
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F271944167650