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DYNAMICS mod

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Nick:
Hi everybody,

here is my shot to the acclaimed dynamics modification by "SSLTech" to avoid the lockup of the dynamic section.
On the output of the 78L15 : solder a diode ( typ. 1N4148) with the Cathode on the output of the regulator, and the Anode to ground. On the output of the 79L15 : also solder a diode, but wire it with the Anode on the output of the regulator, and the Cathode to ground.
Afterwards, when you'll power on/off a channel, the Dynamics cards will always power on, 100% reliable.

Regards








Nick

marcmozart:
I've seen a lot of posts by "SSLtech" on other forums. Is anybody in touch with him. Would be awesome to get him on board!

The mod you're describing, has this been solved by SSL in later revisions? There is no point to do this on my 1991 G or is there?

waltzingbear:
Keith is recovering from some ill health right now, on the mend, but it was very real.

Alan

marcmozart:
Bless him, hope he gets well soon.

guy_4:
Hello All,
Just for the record, I am the person who informed Keith Andrews ( a.k.a " SSL Tech ")  of this problem, and the solution that I implemented to correct it.
It was a long time ago, mid of the 90's.
It took me a bit of time ( long ! )  before finding why the Dynamics section of some channels of the SSL 4048E were not working after a power Off/On.
And this... randomly...  !    :(
Originally Keith though it was coming from the electrolytic caps around the regulators that were aging, and cause of the trouble. But it was not.
Because it is an original wrong design from SSL.
The application notes for the 78L...and 79L... regulators specify a reverse diode between the output terminals. ( as for all regulators, generally )
It prevents the regulator to turn its current protection circuit " On"  at the start, and to " lock-up " .
I contacted Basingstoke at this time to let them know of my " discovery ".
I got no return on this, nobody from the factory ever contacted me back, as they usually did with me when technical problems showed.
Along the years I modified several 4K/6K that I met on my service calls, and that showed the problem. ( and that was often known by the studio owners but with no answer to solve it )
I am sure that even today it remains many consoles on the market with this problem...
Best,
Guy

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