Mccurdy AM-487R amp anyone have shematic or pinout for connector?

Hey I came across a Mccurdy AM-487R and I would like to convert it to run without it's DA-505 base (don't have it) as a standalone amp.

Does anyone have any docs on this thing? looks like a nice piece of gear if I can get it going.

Found it in the trash at the radio station.

radiomuseum.org would be the first place I would look for something about this.

thanks for the advice squarewave.

I checked there but didn't find anything on this amp. There is another mccurdy amp there though but the older tube one, this one is solid state.

Ok, so you found a 20W RMS amplifier, mounted inside a cool looking cabinet.

Balanced input, balanced output, single volume control.

It plugs into  a 6 unit rack, not sure what does the rack feed it.

Suspect the AM487 gets traight 115V, since it sports a line fuse and switch.

I would **carefully** map the connector, IF it is set up to receive Mains I would power it up through a current limiting bulb and check whether it powers on or not.

The general catalog:  https://www.americanradiohistory.com/Archive-Catalogs/Miscellaneous-Manufacturers/McCurdy-Broadcast-Equipment-70s.pdf

Apply no signal yet, and keep volume set to 0, it has transformer output and you could blow it without proper load.

Post a picture of the back pannel, showing connector details ... any labelling?

thanks here are some photos I think it is a mono amp but it is packed intight in there so a little hard to follow the wires there appear to be 4 transformers ,  3 blue which I haven't found any info on yet and a silver tube one.  I believe that one of the big blue ones is  for mains voltage and the other is for output at first I thought it might be a stereo amp but they have different numbers on them and different wires coming out

here is a picture of the back

I have tried several times to post a photo of the connector but it keeps"failing security checks" so IO will have to try again ater.


but it consists of two 24 pin header plugs  and the only labeling is the connector numbers 1 and 2 and the pin numbers 1-24

We're not going to be able to figure out what the pins do from a pic anyway. Look at the block diagram in that catalog and then trace through the circuit to figure out what each pin does. Maybe schematics of other units in that catalog will give you
a clue. Of course it's not using all 24 pins. It's probably using like 10.

It looks like a nice line amp though. There are some nice transformers in there.

thanks for the input yeah, with the block diagram I should be able to figure out.

I am curious as to what the silver tube in the noval socket is though it has shielded audio cable going in and out of it but the input and output transformers are definitely the blue ones.  anyone have an clue?

lazlos said:

thanks for the input yeah, with the block diagram I should be able to figure out.

I am curious as to what the silver tube in the noval socket is though it has shielded audio cable going in and out of it but the input and output transformers are definitely the blue ones.  anyone have an clue?

Click to expand...

Odd, from the photo I would have thought that was a multi-section capacitor.  Pop it out of the socket and see if there are any markings.  Could also be a relay.

> the input and output transformers are definitely the blue ones.

There has to be a Big Lump for the power transformer. (As said, this thing eats 115V AC from a wall.)

The OUTput transformer may be a similar size.

Input transformer would be far smaller.