Ampex aa620 power circuit , earth wire problem!

hamed kh

New Member
hi , recently i bought an very old 1968 ampex aa-620 mono block amp with speaker(actually its an active speaker but i bought the amp alone!) the power cord has 3 wires as you see , and one of them is earth I guess. the problem is my electicity line has no earth and has just two hot and neutral wires. but the circuit is not just what i saw before.the hot and neutral are conmected together with 2 caps between and..
now that im using it, should i change it or it work as it is and just connect H and N?1544374384634609936373.jpg Screenshot_20181209-203256.png
 
The center connection is earth ground. If the plug has 3 connections just use a cheater plug that has hot and neutral. Where are you located as to what is the wall power is? 120 Vac,220Vac. Welcome to AK.
 
The center connection is earth ground. If the plug has 3 connections just use a cheater plug that has hot and neutral. Where are you located as to what is the wall power is? 120 Vac,220Vac. Welcome to AK.
thank you, the wall ac is 220. and i have plan to add a 220 to 110 v trans befor the at the gate. is it ok to just cut the caps and earth ground parts off?
 
Those capacitors are there to filter line noise, shunting high freqs to ground.

You should use a safety capacitor ("X2/Y2" rated) since the capacitor is connected probably to the amplifier chassis, or metal parts you could touch. If the capacitor fails shorted, the line voltage can reach the chassis. That's why you see a 1400V capacitor there, to increase safety, but modern safety caps are manufactured to never fail shorted, and can take peaks of several thousand volts.

You can use a plug without ground connection, but instead of cutting the ground plug, in the XXI Century, I'd suggest to add a ground connection to your electrical installation. Electrical safety has improved a lot and installs without a proper ground became illegal in many countries, to save human lifes. You could follow the advice of safety engineers and install a ground connection, even if the laws don't force you to do it, you can save a human life including your own.

Edited: Even if the ground is not connected, the capacitors stay connected across the 220V line, that's why you need an "X2" capacitor there. An X2 safety capacitor is warranted to never start a fire in case of a fail. Also, I see the capacitors are connected before the power switch, that means they will be energized all the time while the unit is plugged to the wall.
 
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