Quote:
Originally Posted by Boulevardier
Quote:
Originally Posted by DMcMahon
With PB head wiring disconnected use a DVM (ideally with a low value resistor in series) to measure the resistance of the head. This could (but in my experience normally does not) partially magnetize the head (if head not open circuit) then possibly later requiring the head to be demagnetized later for best HF reproduction.
David
|
Actually David, he could just measure the resistance from EF86 pin 9 to chassis (without the extra hassle of disconnecting the head), since the only other paths to chassis should be the 2.2 M ohm grid leak resistor and the grid resistance of the EF86 itself - neither of which will affect the measured head resistance significantly (I'm assuming that it's the Mk 2 schematic we're working from). Doing it this way will also check that switch S1 is doing its job. The DC resistance of the head is specified as 1.1 kilohms.
Mike |
After rechecking the reading from Pin 9 to chassis is 2.4Mohm in play mode. In record mode it is 0.5 ohm.