AVR 2 TBC Problem

[David Willis]

Hi,

Currently working on an AVR 2 (it's been a while since I last worked on one
of these) that's got a TBC problem. I tracked down and replaced the dead
chip (A32) that fed clocking to registers at the front of the D-A and found
the non working chips (A4 and A56) on the two line delay that I replaced
with working spares from a non working board. I appear to now have all 24
bits going into the memory, out again, through the 2 line delay and into
the D-A however please see attached photo of TBC out when fed with the ramp
from Bd 17. It appears I'm still missing bits.

Fortunately I have some spare boards and have tried swapping out the A-D,
Clock Gen and Burst Store Gen in turn each with no change. I don't have
another working D-A. For info I've got the TRW A-D with associated bypass
board.

The machine is better than when I started but not yet fit. If anyone with
greater experience has any ideas where I should be looking I'd be grateful
for the advice.

Thanks.

David
Engineer, TVT

[image: Inline images 1]
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