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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: stevetoney on August 12, 2009, 09:33:31 AM
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I had a V3 that went DOA after I attended Summercamp this year. A number of people asked me what had happened and I wasn't sure. I sent it in and got it back awhile ago, so I figured I'd let everyone know what my problem was.
Turns out that a chip in each channel was fried. Seems it was my fault after all and that I must have either plugged in or unplugged my mics while phantom power was on (DOH)...a definite no-no. The reason I say that I must have done this is that when I got the V3 back, the RMA sheet simply stated that they had replaced the two chips and that these chips typically fail as a result of the mics being plugged in with phantom power on. Since both channels failed at the same time, I'm sure it was my fault although I wasn't congnitive of my fuck-up when I made it.
Anyway, just providing a reminder to everyone to make sure your preamp is OFF before connecting or disconnecting your mics.
MAJOR KUDO's to Grace though because when I contacted them I did mention casually that I'm the new owner of the V3. Even though the warranty on this particular unit had expired at the beginning of this year, they fixed it at no charge because they wanted another happy Grace customer.
PLUS TEE'S TO GRACE!!!
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That's great to hear.
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Those guys at Grace are awesome.
I had a similar issue with a V2 back in 2001. Thing just fried, sent it to Grace, unit was out of warrenty and they fixed it for free.
Glad this worked out for you!!
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I wouldn't consider that your fault. A pre with phantom power has got to be able to tolerate that sort of thing. There are a lot of ICs that will die if they suffer a spike like that, so you add a few external components to protect them.
Does this mean that we can plug mics into the littlebox with the 48V on, and everything will be okay?
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i have heard mixed reviews on the 48v plug/unplug issue myself
i have seen people do it too
i always turn it off though - better safe then sorry
anyway its seems grace is always doing the right thing, which you can't say for many businesses these days
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hmmm.... interesting... while i always power up after everything is connected, my earthworks claim to love a hot plugin (its in the manual)... i had always though it was the mics that minded the hot plug, and so i figured with the EW it could be done... with this info, it appears the gear is also a variable that i hadn't considered.
back to cold plugs for all.
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I wouldn't consider that your fault. A pre with phantom power has got to be able to tolerate that sort of thing. There are a lot of ICs that will die if they suffer a spike like that, so you add a few external components to protect them.
Does this mean that we can plug mics into the littlebox with the 48V on, and everything will be okay?
Not unless you want to risk it. I think his point is that circuit design could and should prevent this from being a concern, but if the circuit isn't designed with the proper protections, then you're taking a chance if you don't power on in the right sequence, as I discovered!
jeromejello...while my experience was that parts of the preamp were damaged, I don't see where the logic is far off. If there are surges that result when you plug stuff in and out and those surges are prone to cause damage to sensitive parts, I'd think that there are scenarios where damage could happen at the mic end too.
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I think, and I could be recalling this wrong, but the only preamps that are able to handle what happened to Steve are those with output transformers. Given that transformers used for output balancing are almost impossible to burn up, the fact that they also offer compelte galvanic isolation from the rest of the preamp circuitry is another nice characteristc of transformers used in this application. Although I still try to make sure nothing is powered up when the rig is being hooked up, or nothing is disconnected with phantom on.
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I'm really surprised (I don't wanna say "shocked") that a V3 could be damaged in this way. Yikes! And thanks for the posting.
I normally turn phantom powering off before connecting or disconnecting microphones, but that's to avoid the momentary burst of noise through the headphones. Heck, at AES shows I've seen engineers from Schoeps change capsules on their microphones with the powering still applied (though they don't recommend the practice in general).
--best regards
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Heck, at AES shows I've seen engineers marketing people from Schoeps change capsules on their microphones with the powering still applied (though they don't recommend the practice in general).
--best regards
Fixed that for you. ;)
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All of our mic pres have clamping diodes on the inputs to protect the ICs from static and hot phantom plugging spikes. Turning phantom power on after the mic is attached will minimize the stress to the components.
Tonedeaf, I don't think this was at all your fault..... The chip could have just failed. Only one of the INA163 chips in your V3 had failed, I decided to replace the other in case it had been stressed.
Neal
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All of our mic pres have clamping diodes on the inputs to protect the ICs from static and hot phantom plugging spikes. Turning phantom power on after the mic is attached will minimize the stress to the components.
Tonedeaf, I don't think this was at all your fault..... The chip could have just failed. Only one of the INA163 chips in your V3 had failed, I decided to replace the other in case it had been stressed.
Neal
Yet another reason why I love these guys!!
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All of our mic pres have clamping diodes on the inputs to protect the ICs from static and hot phantom plugging spikes. Turning phantom power on after the mic is attached will minimize the stress to the components.
Tonedeaf, I don't think this was at all your fault..... The chip could have just failed. Only one of the INA163 chips in your V3 had failed, I decided to replace the other in case it had been stressed.
Neal
Yet another reason why I love these guys!!
+1
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spyder9, I promise that I get the joke, and unfortunately for a lot of other microphone manufacturers your guess would probably be right. But I really was referring to my friend Jörg Wuttke, the chief engineer of the company at the time (mostly retired since then).
Until two years ago Schoeps never had any marketing employees at all; now they have one working part-time. Even that would have been impossible during Dr. Schoeps' lifetime. His attitude was, "If you want my microphones, you will come to me." Telefunken, Studer, Siemens and Philips "came to him" and thereafter sold many Schoeps microphones--but under their own labels, not Schoeps'. As far as I can determine, the company didn't publish any sales literature for the first ~15 years after it was founded.
When I was first looking to try a pair of Schoeps mikes in 1974 there were no dealers in the U.S.--just a hard-to-find distributor in rural Pennsylvania who would order them from the factory if you sent him full payment in advance (which I did, and then waited two months for delivery). The existence of the microphones was more like a rumor than a definite fact.
So no, it definitely was not a marketing employee whom I saw doing what I described, since no such employee existed; it was the engineer who co-owned the patent on the design of the microphone's electronics.
--best regards
P.S.: I would gladly add my vote for Grace's customer service and technical support. They're first-rate.
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That's it I can't stand it anymore, I want a V3!
Eating American cheese sandwiches until my bank account agrees..
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That's it I can't stand it anymore, I want a V3!
Eating American cheese sandwiches until my bank account agrees..
Don't worry......they'll be passing out the "gub'ment cheese" real soon.......save yer money!
;D
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Great story, tonedeaf :coolguy: