Audio xformer in Nintendo monitors

[stratjakt]

In Nintendo monitors, both Sharp 2001N and Sanyo 20-EZV's, after the audio amp circuit, and before the speaker, there's an isolation transformer. 

The available schematics dont list a particular part number (they're from Atari games which dont use this part, IIRC), but just list "Audio Isolation Transformer".

This is pretty much to prevent hum on the speaker, by isolating it from the ground loop, am I correct?  The difference between xformers would basically be sound quality (how they handle different frequencies), is this correct?  Would the cheap little xformer at Rat Shack work in this application, or what specs do I look for?  Ie; 8 ohm output impedance to match speaker, etc..

[Ken Layton]

It's an audio output transformer. It matches the impedance of the amplifier to the speaker. I believe it's around 1,000 ohms primary impedance to 8 ohms secondary impedance. I believe the audio wattage of this transformer is around 10 to 15 watts.

Radio Shack # 273-1380 might work, but I don't think it can handle the wattage of the amplifier at loud volume settings (I don't have any specifications on it). Heck, it's only around a $3 transformer so it's worth a try.

[stratjakt]

Worst case scenario I'd just 'splode the transformer, and not kill the monitor, right?  It won't be that loud, my wife would get pretty sick of hearing the theme from Donkey Kong and if she's unhappy the whole world is unhappy.

I actually scavenged the transformer off the Donkey Kong (Sanyo monitor) to put together my PC10 (Sharp monitor), it seems to work fine, and fit in the vacant spot perfectly and had the same plug.  The schematics I could find said nothing about it, but they were from Atari games, which IIRC don't use the amp in the monitor.