ADM 770 discrete op amp footprint

[dogears]

A friend asked me to help replace an op amp in an ADM 770 preamp. Does anyone have any reference for the pinout and footprint of the discrete amps? They’re similar to a 2520 but don’t look identical.

 

[Brian Roth]

All I have here is a schematic for their 202 opamp. The 770 used the earlier 201 opamp which may have the same footprint, but I don't have a drawing with the footprint for either version.

Bri

 

[mjrippe]

Attached are 202 schematic and dimensions, as well as 770 schematic.

 

[dogears]

Thanks! I think the 202 looks right.

 

[robertloud]

Just seeing this, but I seem to remember I also have the schematic for the 201 version. I will check and report back.

 

[robertloud]

Hey, just following up. I found the schematic to the model 1202, not 201. I've read elsewhere that the 1202 is what is used in the 770 modules, but the schematic mentions 201. So not sure if there's a different op amp used, or if they changed the name for the same module. The ones in most of my channels are potted and in blue plastic, with a few channels that are in black plastic. I looked for any markings on the actual module and couldn't find any, but haven't desoldered any to see if there's anything written on the bottom. (I started to, but the pins are bent flat against the PCB and I decided it wasn't worth tearing up the fragile traces)

Anyway, the schematic is actually identical between 1202 and 202, the only difference is that the pin spacing is different! The 1202 is closer to the API footprint (one of my channels even has an original Melcor 1731 that a previous owner soldered into it!), while the input pins on the 202 are spread out further from each other. I can upload the 1202 info I have to the Technical Documents section once I get a chance to scan them in. I also found the schematics to the 1540 EQ module and have seen a lot of people asking about that one, so I'll upload that as well.