Re: 7704A Vertical Amplifier Issues

Mark Vincent

Albert and Barry,

The reason I specified 1W for the 33 ohm resistor is because I measured 3,13V across the 33 ohm resistor. The base voltage is 14,4 and the emitter voltage is 17V. I measured this in mine that is working fine at the time of this post. I know the EB voltage is not standard ,6-,7V. The reason for the two longer leads on the out is to the load side of the distributed plates. That is what it is supposed to be. Having them go to pads would increase the C of the circuit.

The nonlinearity in the horizontal circuit may be due to bad parts. I can give you a list of parts that should be changed. If necessary, I do have a spare horizontal board that is known good if you need one. Check to see if the inputs are linear with another oscilloscope. I do know some resistors should be increased in wattage. I did add heatsinks with compound to the outputs to keep them cooler.

If Barry needs 33 ohm 1W and 5600 1% I can send them to him. The 33 ohm does not need to be 1%, 1W yes.

The output IC is operating normally at warm. I so happy you got the vertical problem fixed easily. I did add a 12V fan to cool the two circuits. It is running less than 12V. I like my items to be cooler than original to give longer life of parts.


Join to automatically receive all group messages.