No picture, Hole blown through LOPT. Had problems tracking down replacement – little tip given to me by Hantarex engineer – you can use the LOPT from an MTC9000 as long as you cut pin 2 off. (If you leave it connected, you will get a direct short to GND)
Similar Posts
Crazy Balloon
No Sound. Signal at output of SN76477 pin 13, follow through to input of sound amp, then from output until we reach electrolytic capacitor used to decouple connection to speaker. Signal going in, nothing coming out – replace capacitor sound back to normal. Only drawing a few pixels of player balloon sprite. Following the schematics,…
Missile Command
ByadminThe board originally failed to get into the game, instead resetting just after drawing the ‘MISSILE COMMAND’ logo. Test mode faired a little better, managing to report RAM OK, MAP OK and ROM OK before resetting. Ram and Rom checked out OK using the Fluke. Measuring various CPU signals revealed that the interrupt seemed very…
Sega System 16
ByadminAltered Beast – Colours missing, no reds, other colours looked like diminished palette (like windows in 16 colours) – used test mode to perform ram test, and one ram chip identified as faulty (I10). Replaced this and red was back, but still reduced pallette. Looking at colour circuit, and it uses resistor arrays driven by I11…
Gorf
Capacitor burnt. (game board), particularly at C37 the capacitor was showing signs of extreme heat. Replaced them all with 22uF 25V axial electrolytics. No Speech / Some SFX missing. (game board) Output from speech chip SC01 was OK, as was output from IO Custom (X3). checked transistors in output stage and 2N4401 was faulty. (Q2)…
Gallag
Ran through self test OK, came up with chequer board screen and then reset most of the time. Occasionally would start game, but with credit noise continually playing and credits rapidly counting upwards. This is caused by CPU 4 (E5) not running properly. checked the eprom and ram (C5,D5 and E5) and ram was faulty….