Datasheet for DM-171 Dynamic Noise Reduction IC in '85 Delco car radio

[DaveBerlinetta]

I'm restoring the radio out of my 1985 Camaro Berlinetta. While I have it apart, I'd like to add an audio input jack that would be fed from a MP3 player or Sat radio. I plan to use a set of unused inputs to a MC14052 Dual 4-CH Mux that controls input (radio/tape deck) feed, and use a NC/NO 3.5mm jack to force the Mux to the open channel I'm using.

After the Mux, is an IC that I just can't find any specs for. The Delco schematics show it as a DM-171 DNR. It's a 14-pin DIP, and here's what is listed on the drawings for it:

1 - 8v B+
2 - 4v L. Audio IN
3 - 4v Out FDBK
4 - 4.1v L.Chn Out
5 - 3.1v SUM Out
6 - 0.8v SUM RTRN
7 - 0v GND
8 - 4.5v GAIN Out
9 - 0/1.2v SUM 19Khz *
10 - 3.3v PK DET Out *
11 - 4v RT Chan Out
12 - 4v FDBK
13 - 4v R. Audio IN
14 - 4v BYPASS

* - DNR OFF/ON

I've never worked with an IC like this before. I haven't had a chance yet to put a scope on it, probably this weekend. I can take some educated guesses at the descriptions, but I would really like to see a datasheet. Especially how the DNR OFF/ON works.

I've been searching for about a week now, that's how I found this site. There are no marking outher than Delco's "DM-171".

Anybody work with this chip before?

 

[DaveBerlinetta]

Go figure. Just after I post this, I find a match with LM1894.

Thanks anyway!

 

[dentaku]

I know this is a very old post I'm wondering how to find out what the common part numbers of these Delco/Delphi components are?

It's annoying that they rename their chips so there's not obvious way of finding datasheets for them.
I just opened up an old Factory Delco CASSETTE-AM-FM radio, Model # 09367585 mostly to salvage the potentiometers and buttons from it and I see that most of the components seem to have been custom made for Delco/Delphi. Lots of them start with 014 (even what looks like voltage regulators) which would lead me to believe they're specific to the manufacturer of the radio and not the regular part numbers.

I'm restoring the radio out of my 1985 Camaro Berlinetta. While I have it apart, I'd like to add an audio input jack that would be fed from a MP3 player or Sat radio. I plan to use a set of unused inputs to a MC14052 Dual 4-CH Mux that controls input (radio/tape deck) feed, and use a NC/NO 3.5mm jack to force the Mux to the open channel I'm using.

After the Mux, is an IC that I just can't find any specs for. The Delco schematics show it as a DM-171 DNR. It's a 14-pin DIP, and here's what is listed on the drawings for it:

1 - 8v B+
2 - 4v L. Audio IN
3 - 4v Out FDBK
4 - 4.1v L.Chn Out
5 - 3.1v SUM Out
6 - 0.8v SUM RTRN
7 - 0v GND
8 - 4.5v GAIN Out
9 - 0/1.2v SUM 19Khz *
10 - 3.3v PK DET Out *
11 - 4v RT Chan Out
12 - 4v FDBK
13 - 4v R. Audio IN
14 - 4v BYPASS

* - DNR OFF/ON

I've never worked with an IC like this before. I haven't had a chance yet to put a scope on it, probably this weekend. I can take some educated guesses at the descriptions, but I would really like to see a datasheet. Especially how the DNR OFF/ON works.

I've been searching for about a week now, that's how I found this site. There are no marking outher than Delco's "DM-171".

Anybody work with this chip before?

 

[shokjok]

I found ICs beginning with 014 in an ECG Cross Reference Guide, also available on their QuickCross software. I don't have any GM radios for comparison.
I disassembled an engine computer from my Dodge Ram truck ( single 60-pin connector), and found two ICs there can be replaced by a 6821 PIA IC. The rest are custom ICs, no data available.
As for the DM-171's I may have loose ones from salvaged radios that I can give you, no data sheet was obtained from a GM dealer. The radios I salvaged were loose in a scrapyard.