DDA console weirdness

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Scenaria

Well-known member
Joined
Jun 3, 2004
Messages
948
Location
Florida
soo im killing myself trying to figure this one out...

This desk is a DCM232.. for those who dont know it is one of those desks that does alot of the "logic switching" from the master section.. things like EQ on/off insert pre post etc...

select the channel and turn on/off the I/O functions from the "cap"

works just fine but... if say I turn on a bunch of functions on a large number of I/O 's everything is ok until I select a channel that has nothing turned on.. when I switch back to a channel with alot of functions turned on theres a quick negative spike on the 12V rail. this "glitch" causes the consoles computer to reset.

Ive tried putting some caps on the 12V rail coming out of the p/s with no success.. I tried putting some caps localy near the area where I believe the problem is occuring with no success.

its a very very quick glitch and it only seems to occur when theres a large load swing on the rail...

very frustrating trying to locate this problem... if I can get this one knocked out the board will be like new :\
 
Bill,

I think that there's no actual switching done at this juncture, merely that a display lights up to indicate the status of (unchanged) switching states on the newly addressed channel as you step between channels..

Correct me if I'm wrong, Scenaria...

Keith
 
are there any caps (ie tantilum) that are closer to the physical locations of the physical devices being switched(relays). they kinda look like little yellow beads between the power rail and ground. if there going kinda flakey the can not hold the appropriat amount of voltage and can cause state changes downstream from the poit of the faling cap

Wilebee
 
check you ground connections. What device does the switching?
 
damn those gremlins! Sounds like your PS doesn't supply enough current to support such a swing in voltage. I get this a lot in motor switching that i do at work. maybe a bank of caps to supply when this is happening? if the logic uses a lot of fet/bjt I/O then you might be shooting through somewhere...? what type of power supply does the computer use? can you use a separate supply for it instead of a common one?
 
schems are tough on this one...

tons of them that lead ya in circles :)

im going to try strapping some caps locally inside the computer... perhaps this will prevent it from dropping... Guess I should have tried that in the first place...

I was trying to locate the *fault* not sure where to begin..

I think I could perhaps put the bench supply on the comp to isolate it.. see if its fine at that point
 
the only way I'll learn is by doing it myself :)

shit... the damn trident I sold last year put a fire under my ass.. had about 15 things on a punch list and had to get em resolved within about 48 hours... before the buyer came down. keef did come by for moral support though :)

maybe if I can find some time to getaway from sorting damn screws an hardware for the la2's :)

ive never sealed soo many plastic baggys since the days of... oh well it was alot of baggies :green:
 
you need one of those TEW impulse sealers.
That's what i use to...ummmm...seal....errrr.....

hey howabout those Dolphins!
Man what a quarterback.

:oops:
 
Has this DDA a SSM2017 in the frontend?
When yes , you will get more and nicer problems withit aswell

Sometimes the ssm will make the problem , have changed it a few times than noise and powerrail are back and stay clean.

Dont know if you have the same problem , it took me many many hours of time to find out that the ssm2017 was doing this.
Have had 2 tables to repair with same problem.
 
ever work with an otari concept? It sounds like a similar console to you DDA. analog in design but digital control surface. I used to work in a studio when I lived in Boston that had an otari concept. had a similar situation going on which was caused by static electrocity. but would happen usually in winter when you get lots of static bulid up from dry air/dragging feet on carpet in doors. Anyway if you static shocked the board it would cause it to flip out and reroute the bussing and other assignments. pain in the ass. I am trying to remember what we did to fix.
 

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