Name: Michael Kaus
Email: cnmkaus@home.com
Subject: MM HD-130 head
Thread: 280
Time: Sun, 25 Nov 2001 00:40:26 UTC
The heads are basically the same. The changes being that they remove the mid control and replaced it with a 820 ohm resistor and removed the bright switch and the .015 capacitor so no bright. Other than that they are the same. The real changes came when they went to the solid state driver and eliminated the bias wheel adjustment. The best i can see is that the bias voltage is positive not negative going to pin 5 as a control voltage. Obviously this works as long as it is more negative than the voltages of the differance between the plates(I think). If Steve K see's this, maybe he can shed some more light on it. I have been through one of the conversions from tube driver to solid state-it wasn't pretty! The patient survived only to suffer a massive heart attack from dropping a pair of dykes on to the rectifier board while live.BANG. 725 volts won't bounce around long before things melt. Mike.