- Blog entry posted in 'Teardowns', April 10, 2013.
This time i'll write about Trio AG-220A audio generator, which i use as signal generator, as i lack proper signal/waveform generator. I got this one from school, for free :).
This has sine/square wave output, 0/20/40db attenuation which all are selected from slide switches. Output magnitude is about 14VPP at sine, little bit lower at square, as it supposed to be, if I'm not terribly wrong. Square wave also has slight distortion at very low/high frequency.
Power switch is slide switch too, accompanied with orange power on light. Maximum frequency is about 200khz. Frequency is set from rotary switch, which has x1/x10/x100/x1000 prefixes. Final adjustment is made by rotary knob, which is also wired by momentum to bigger wheel, which is analog needle meter along with axis to variable capacitor . This is pretty nice looking to me, I'm old fashioned and i like this type of meter compared to digital, but both has pros/cons but let's not talk about that now. You notice the output magnitude knob is different to others, this is because i had to replace the original one.
Connectors are standard screw-type 4mm banana jacks with hole to wire, and other is chassis ground. Output impedance is 600Ω (ohms)
Back panel has 4mm connectors for chassis ground and SYNC INPUT, for calibration maybe? There are also couple places for screws, their purpose is also mystery, mounting perhaps?.
And traditional metallic name-plate is also found, says model#, seller, etc....and selling date is 19 October 1979, so this has to be at least older than that. Also, this is Made in Japan, well good quality so far.
Metal case is hold by 6 PH1 metric screws, and it opens easily. Carrying handle is also well mounted, with PH2 metric screws.
Now the inside:
None IC's were used, all components are discrete, resistors, transistor caps and stuff. transformer is small, but what is strange IMO is that live/neutral dont go straight to transformer, and its windings has 3 wired other side, and 4 wires other side. I didn't reverse-engineer it or have any schematics so i cant say anything about transformer or anything else's topology Also, there are no connectors inside, all are soldered, but without isolation of any cind like heat-shrink/hot glue. Mains fuse is on neutral side, not on live. Earth is also soldered to chassis.
But, again nice find, build quality was good and interior was interesting.
Comments welcome!
