14 May
2008
14 May
'08
3:59 p.m.
Eric wrote:
The G888 sense amps are designed to oscillate when no
input is present.
Thanks, Eric - I'm glad I asked. I wrote a little program to read the
tapes (only about three lines of code - all it has to do is set the "GO" bit
in the TD8E command register) and I find that one of the units does indeed
give a nice 30kHz square wave on the timing track while the tape is moving.
The other unit unfortunately still gives the bogus 400kHz oscillations no
matter what.
I'm guessing that must mean that either the R/W head or the relay card is
bad. I can test the relay card by swapping it with the other unit, but luck
being what it is it's probably the head.
Darn - I assume TU56 heads are unobtainable these days.
Thanks again,
Bob