30 Jul
2014
30 Jul
'14
12:25 p.m.
Thaks to all helping hands!
I think now i found an answer to my question on pdp8online.com.
Field Sevice Tips <http://www.pdp8online.com/bklatt/703.png>
So i have now adjust my G888 Boards. Function check of the drive follows
now.
On one G888 i have somthing noisy in the scope view. Maybe this is my
problem with the TU56.
Marco
Am 30.07.2014 18:28, schrieb Al Kossow:
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.