Bucket Problem - 4000G -Now channel is on 8 modules

[perfectsnd]

I was swapping modules from one bucket to another. I had the power off on both buckets (power to console though).  I was reseating the new module and I saw power go to the module as I was trying to reseat the module and I saw the lights on the rest of the modules in the bucket flicker. This was very strange and never happened before. I pulled the module out and powered off the console and then I reseated the module. When I powered on the bucket all the channels were in overload even though no signal was going through them.

I then powered off the bucket and pulled a series of modules out and powered up the bucket and the remaining modules were in overload still. I removed all the modules from the bucket and put the extender card in with a single module and that module went into overload immediately and I heard a whine bleeding through the main speakers.

Does anyone have any idea where to look? Has this happened to anyone before?  All the rest of the buckets are fine and working properly.

[horizonsound]

Check the circuit breaker for the bucket is not tripped. That would be my first guess.
You’ll still have status bus voltage going to the edge connectors, even if you turn the buckets off.

Anthony.

[perfectsnd]

Where is the circuit breaker for the bucket?

[horizonsound]

Next to the switch you turned off for that bucket.
There are two per bucket. One for +18v, one for -18v.

[perfectsnd]

The circuits aren't tripped and there is definitely power getting to the bucket.  When I power up the bucket is when the channels go right into overload.

[walrus]

Have you measured the voltages on the extender card.
It may be that one of the switches is broken and you are only getting either +18 or -18 volts.

[perfectsnd]

Yes. I have measured the voltage on the extender card. I am getting -18.8 and +19.0 at the extender card (pins 37-39) and pins (48-50).

I did some investigating. I put a known good module into the 9-16 bucket (that is where the problem)was and the module powered up fine. All 8 original modules that were in bucket 9-16 go into overload if I put them in a different bucket. This leads me to believe that this is a module issue on all 8 that were in the bucket.

So now we are chasing down a problem on all 8 modules.  Where would one look if a module is going immediately into overload?

[skipburrows]

Hi there, I would check the pico fuses at the bottom of the module measure those on continuity I’ll bet you one of them is blown. Try and replace with same value if possible if they are blown. Good luck

[perfectsnd]

That was the next step I was going to try. I believe I have a decent stock of these.

I will report back.

Joe

[horizonsound]

As i understand it the overload indicator works off a differential amp. If you lose a voltage rail, the LED will stay on. It is driven off the 82E13 card.

I'd be looking at the fuses on the modules as well, which would have been my next suggestion, but to blow 8 in one hit is a rare event. Though not impossible.

Anthony.

[skipburrows]

Yeah my real concern is if his power supply went to raw Dc. But if he’s measured that voltage and that looks ok then it’s a bit of a mystery. The only thing is if the breaker on either rail tripped and when running on 1 voltage it went over current and the fuses blew.. just a possibility..
Cheers

[perfectsnd]

Yes. All the -18v fuses on all 8 channels in that bucket were blown. I replaced them all and the bucket is a happy camper again.