DennisD wrote:
As of now my 2 issues a

1. I'm not too sure how significant the individual channel bias
adjustments are. If you are familiar with the Studer procedure the
channel gets set to 3dB over peak, then the master is set based on
tape...in our case 1.75 over peak. I can only get 1dB over on the
channels (the pot max clockwise), but then the master has plenty of
room to get the 1.75. I don't know if the channel adjustment is a
problem or not.

The amount of overbias you want depends on the kind of tape you are using.
It sounds to me like you don't have enough bias voltage to get the thing up
to proper level. You might be able to fudge it by maxing out the master
control and then doing all the bias with the channel controls, but it will
be more time consuming.

This does sound like it could be an incorrect head impedance issue, just
like the playback issues. But I would worry first about the playback
problems since until you get proper playback calibration, you cannot believe
your record calibration.

Does the bias trap control null out completely, or are you at the end of the
travel and still see some leakage? If so, you absolutely know the head
inductance is wrong (which implies the impedance is wrong).

2. Erase depth isn't very good. To get the very minimum erase I have
the master set to over 6V p-p. Tuning the channels will give me about
66dB erase and tons of 'rocks' noise. After a second erase pass the
signal is then completely gone. I think this indicates the erase head
is the correct width and height, but that is for John to tell me (I
just sent him an email tonight, so I won't hear from him till
tomorrow). Does anyone have any ideas on erase issues like this?

Your erase bias voltage is not high enough. What erase bias voltage are
these heads supposed to have? If they are high-Z, 6V is not going to be
anywhere near enough. What are the impedances and inductances of the
original heads and what are the impedances and inductances of the heads you
have fit on?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."