scott2000
Well-known member
I have an Apogee Rosetta200 that has -12.5 ish Vdc at it's input xlr pins 3 only. All the supply rails are where they should be everywhere as far as I can tell (-15/+15 etc). Pretty sure all various rail caps to ground are fine but it's hard to tell without starting to remove stuff.
Apogee can't provide schematics and,I was told in many cases, they can't provide service for this because of parts unavailability . They have been great and corresponded with me with some checks and I'm waiting to hear back from them on my findings .But they are really busy and it's taking a little while longer than I can justify keeping in limbo if there's another way. I'm hoping to hear something back from them this week.
Apogee hasn't said if this DC voltage is normal or not. They just asked me to check my supply rails because they said the 12v should've been 15 but, it is 15 where it should be. It's not clear if they meant, that the pin 3 should've been -15Vdc...but I wouldn't think so.
Depending on the load at the inputs, the negative dc voltage will vary. With a 5k pot for example it'll vary from almost zero to -2.5Vdc....
There is an issue that when nothing is connected to the inputs or outputs, and selecting analog as a source for digital outs, or analog as a source for analog outs, the meters will jump and stick at -4 on the front panel..not sure if it's a clue
I can use the Aptomizer function which will "learn" an input and adjust the voltage during recording. When doing this with nothing connected, the negative dc voltage at pin 3 will drop to about -7Vdc...not sure if it's a clue.
I started trying to trace the input circuit in hopes that something will stand out. I'm including a sketch as best I could do with my limited abilities and not knowing what these circuits do.
The main CS5361 adc chip is further down the circuit buffered by a couple OP275 chips but I don't think it's relevant at this point since the issue is this first stage it appears?
The unit works fine as far as I can tell and, as long as something is connected to the inputs that brings this dc voltage down, it doesn't seem to be an issue. But there are some things that may not do this depending, and there may be a concern with magnetizing any output transformers with dc if the chance arises?
Any ideas what may be going on? Bad switch? Bad Ad8513? Both left and right channels are behaving the same.
Apogee can't provide schematics and,I was told in many cases, they can't provide service for this because of parts unavailability . They have been great and corresponded with me with some checks and I'm waiting to hear back from them on my findings .But they are really busy and it's taking a little while longer than I can justify keeping in limbo if there's another way. I'm hoping to hear something back from them this week.
Apogee hasn't said if this DC voltage is normal or not. They just asked me to check my supply rails because they said the 12v should've been 15 but, it is 15 where it should be. It's not clear if they meant, that the pin 3 should've been -15Vdc...but I wouldn't think so.
Depending on the load at the inputs, the negative dc voltage will vary. With a 5k pot for example it'll vary from almost zero to -2.5Vdc....
There is an issue that when nothing is connected to the inputs or outputs, and selecting analog as a source for digital outs, or analog as a source for analog outs, the meters will jump and stick at -4 on the front panel..not sure if it's a clue
I can use the Aptomizer function which will "learn" an input and adjust the voltage during recording. When doing this with nothing connected, the negative dc voltage at pin 3 will drop to about -7Vdc...not sure if it's a clue.
I started trying to trace the input circuit in hopes that something will stand out. I'm including a sketch as best I could do with my limited abilities and not knowing what these circuits do.
The main CS5361 adc chip is further down the circuit buffered by a couple OP275 chips but I don't think it's relevant at this point since the issue is this first stage it appears?
The unit works fine as far as I can tell and, as long as something is connected to the inputs that brings this dc voltage down, it doesn't seem to be an issue. But there are some things that may not do this depending, and there may be a concern with magnetizing any output transformers with dc if the chance arises?
Any ideas what may be going on? Bad switch? Bad Ad8513? Both left and right channels are behaving the same.
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