Hi, I’ve got an interesting puzzle involving a BBC-B Issue 7 32k with 8271 (untested) and Econet (working) fitted.
The Beeb has a VC2023 video processor so it has a bodge wire under the PCB (IC6 p27 to IC10 p1, correct as found in another *. thread).
It also has a bodge wire between RAM IC60 p7 to IC58 p7, presumably to fix a broken track after IC60 was replaced.
With socket IC100 empty, the machine works fine. As soon as I install any ROM in socket IC100 (bank 14), the machine is dead: no video output, nothing. I removed all ROMs and it reports “Language?” as expected. With just the Basic ROM in IC100: nothing. Basic ROM in socket 52, 88 or 101 and the machine works fine.
I checked all relevant links (S37 made, S18 north) and continuity-tested all pins in IC100, compared to 101. No shorts, no breaks detected.
Is there anything else, short of using a logic analyzer or scope, that I could check? Any suggestions?
The Beeb has a VC2023 video processor so it has a bodge wire under the PCB (IC6 p27 to IC10 p1, correct as found in another *. thread).
It also has a bodge wire between RAM IC60 p7 to IC58 p7, presumably to fix a broken track after IC60 was replaced.
With socket IC100 empty, the machine works fine. As soon as I install any ROM in socket IC100 (bank 14), the machine is dead: no video output, nothing. I removed all ROMs and it reports “Language?” as expected. With just the Basic ROM in IC100: nothing. Basic ROM in socket 52, 88 or 101 and the machine works fine.
I checked all relevant links (S37 made, S18 north) and continuity-tested all pins in IC100, compared to 101. No shorts, no breaks detected.
Is there anything else, short of using a logic analyzer or scope, that I could check? Any suggestions?
Statistics: Posted by EdVoncken — Sat Oct 19, 2024 9:37 pm