View Full Version : Battlezone Repair Log

10th May 2009, 09:07 PM
Symptom: Intermittent ?ghosting? of vectors, eg the moon very BRIEFLY appearing in the lower half of the screen as well as at the top where it should be, same with mountains, tanks, random lines
Cure: Bad socket at location A3

Symptom: In test mode board let out long, steady tones (AVG board at fault)
Diagnosis: This indicated that the ROM/EPROM at B/C3 was faulty but it was fine as was the socket. Tried to find a chip with a bad output by preventing the board from booting (eg by removing one or more program code ROMs/EPROMs) then disabling the watchdog and putting the logic probe onto the outputs in the relevant section (in this case the Vector Generator Data Shifter). Also made comparisons as I went along with a good AVG board. Pressing the Reset button should then make certain outputs toggle. Found that pin 15 of the LS194 at C5 wasn?t toggling as it should ? replaced this and fault fixed
Cure: Replaced faulty LS194 at location C5

Symptom: Vectors (in mountains for example) extended slightly too far vertically, this made most evident by the vectors that make up the text looking too angular and almost merging into each other. Y axis also became too stretched and eventually was unrecognisable after the board had warmed up
Cure: Bad TL082 at D10 ? replaced

Symptom: Excessive AC voltages (13 and 11 respectively) on the X and Y voltage outputs (should really only be about 2 or 3 VAC).
Cure: The LF13201?s/DG201?s at locations B10 and E10 were faulty ? replaced

Symptom: In test mode, diamond grid and ?brightness? pyramid were shown but no DIP settings, no alphanumerics at the bottom of the display and no indications of some ROMs which I had removed. However, a horizontal line emanated half way up from the centre of the display towards the right.
Cure: Touching pin 6 of the LS670 at location E6 caused the board to reset. Replaced this chip but then the board constantly reset. Disabled the vector machine by clipping pin 6 of the LS244 at R11 and discovered that the LS670 at F6 had bad outputs on pins 6 and 7. Replacing this LS670 fixed the fault (note: remember to reconnect pin 6 of R11 !), eliminated the rogue horizontal line and also restored the normal text, DIP switch settings, etc.

23rd June 2009, 12:24 AM
Nice work

25th June 2009, 03:50 AM
Thanks. :)