View source for PCB Repair Logs Tiger Heli Bootleg

==Tiger Heli (Bootleg)==

<p><table class="infobox vevent" style="width:22em;" cellspacing="5">
<caption class="summary" style=""><b>Tiger Heli (Bootleg)</b></caption>
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<td colspan="2" class="" style="text-align:center;">[[Image:marquee_tiger_heli.jpg|200px]]</td>
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<th scope="row" style="text-align:left; white-space: nowrap;">PCB Image</th>
<td class="" style="">Reserved</td>
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<th scope="row" style="text-align:left; white-space: nowrap;">Pin Out</th>
<td class="" style="">Reserved</td>
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'''Repairer:''' [http://www.aussiearcade.com.au/member.php/1-Arcade-King Arcade King]<br>
'''Forum Thread:''' [http://www.aussiearcade.com.au/showthread.php/9443-Tiger-Heli Tiger Heli (Bootleg) PCB Repair]<br>
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Tiger Heli bootleg I got from ebay a few weeks back with a DKJ cheap.

'''Problem:''' Character graphics missing, some times it flickers very quickly and you can see some. Background is fine, colours fine.<br>
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'''Fix:''' Theres no markings on this PCB so I've taken a pic of the effected area.<br>

Using a logic probe I found the outputs of the 4 74ls166's A,B,C,D (pin14) were all sitting low(closed) but when the graphics flickered on you would get a erratic pulse.
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[[File:Pcb repair tiger heli bootleg 1.jpg]]
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Checking all the other pins I noticed pin 15 (Shitft/Load) was behaving the same which is a good indication of a problem. Tracing that pin back to a 74ls32 @ E output pin 8. The inputs pins 9 and 10 were pulsing normally. Removing the IC I found that pin 8 was sitting high. There are no resistors pulling up that track so we have a short somewhere in one or more of the 166's.

Good trick here is to cut the effected pins, in this case its pin 15. A was already in a socket so I'll just leave that chip out. Looks like chip C is the problem.
Put a socket in replaced the chip and reconnected the pins i cut with a bit of solder, now graphics are 100%
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[[File:Pcb repair tiger heli bootleg 2.jpg]]
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'''Notes:''' Top board does Sound and character graphics, Bottom pcb does background, colour and main program.<br>
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PCB is missing the Sound AMP if anybody has one of these can you please let me know what type of amp is on yours so i can continue testing.
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'''Update:'''<br> 
Ok Bootlegs use a NEC C1181 or 1182 (reversed pinout) Went to put a MB3712 and noticed there was a extra leg. The hole was there but has never been desoldered.
Going by the cap configuration I worked out they use the 1181/2, I've made plenty of external amps before using these for Atari stuff.

Very common amp on bootlegs (so is the mb3712/13 for that matter)

Fired her up sound works great, just need to wire up the controls on the harness now.

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