30 Jul
2014
30 Jul
'14
9:28 a.m.
On 7/29/14 2:20 PM, Marco Rauhut wrote:
What do you want to say with IIRC ?
I see the input amplifier self oscillate if the remot/off/local switch is in off
position.
If i switch it to remote the output of the inplut amplifier go zero.
But on Interface cable i see some data (noise?) on the read lines.
How got the lines RD0, RD1, RD2, RTT and RMT to be if i have the pdp8 switched on and
halted and the TU56 switched on and remote switch in remote position. All lines 0V or all
lines 5 V or the levels
jumping around?
There is positive feedback (R12) across the slicer op-amp. It is supposed to oscillate
when
the tape isn't moving.
If you've looked at the TC08 maint manual, you'll see that the G888's
weren't supposed to be
adjusted in the field.
If you have a second drive, swap G888's until you can isolate which ones aren't
working, then
try to find where (if) it starts working when you adjust the pot. The best you can do then
is find
the edge excursions where it stops working and center it.
Tuning beyond that gets into setting the clock, mark track, and data tracks which
needs to be done with something more than the basic go/no go performance diagnostic.