rlaury

RCA MI-9285 MicPre schematic
« on: July 27, 2019, 02:36:42 PM »
Hi All:
I've looked hi and low for a schematic for this module.  (RCA MI-9285)
 I've got to repair a pair of them.
Would any one have one they might share?

TIA
« Last Edit: July 29, 2019, 03:16:19 AM by rlaury »
When all you have to work with is a hammer,
everything looks like a nail.


scott2000

Re: RCA MI-9285 MicPre schematic
« Reply #1 on: July 27, 2019, 04:36:14 PM »
Is that a pre of a particular unit???

rlaury

Re: RCA MI-9285 MicPre schematic
« Reply #2 on: July 27, 2019, 04:56:15 PM »
It's a mic-pre module  6072, 12AX7, 12AU7. Transformer in/out

Can't find any info on it.

Thanks
RonL

When all you have to work with is a hammer,
everything looks like a nail.

scott2000

Re: RCA MI-9285 MicPre schematic
« Reply #3 on: July 27, 2019, 06:01:03 PM »
Hopefully someone will have something on it. Doesn't look like it would be too terribly difficult to trace it if it comes down to it....

EmRR

Re: RCA MI-9285 MicPre schematic
« Reply #4 on: July 28, 2019, 10:03:07 AM »
Pretty sure that’s tape machine electronics, audio or video. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

rlaury

Re: RCA MI-9285 MicPre schematic
« Reply #5 on: July 29, 2019, 03:12:23 AM »
Here they are. Haven't been able to find anything  :-(
When all you have to work with is a hammer,
everything looks like a nail.

mjrippe

Re: RCA MI-9285 MicPre schematic
« Reply #6 on: July 29, 2019, 11:21:32 AM »
Might be similar to this film sound preamp.  Same tube lineup at least.

EmRR

Re: RCA MI-9285 MicPre schematic
« Reply #7 on: July 29, 2019, 11:42:12 AM »
Might be similar to this film sound preamp.  Same tube lineup at least.

Good bet
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

rlaury

Re: RCA MI-9285 MicPre schematic
« Reply #8 on: July 30, 2019, 12:13:41 AM »
Thanks mjrippe. Looks like a good start.
When all you have to work with is a hammer,
everything looks like a nail.

EmRR

Re: RCA MI-9285 MicPre schematic
« Reply #9 on: July 30, 2019, 12:42:37 PM »
There are at least a half dozen variations of that circuit amongst Photophone, tape machine, and foreign RCA products, tweaked to need.  Some with bridging input transformers, some with 30Ω input transformers, some with 150/600Ω.  Various EQ networks.  Rear end dang close to the BA-21. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde


 

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