https://wiki.arcadeotaku.com/index.php?action=history&feed=atom&title=Power_Spikes_Repair_Logs 2026-04-14T05:20:03Z Revision history for this page on the wiki MediaWiki 1.42.1 https://wiki.arcadeotaku.com/index.php?title=Power_Spikes_Repair_Logs&diff=14980&oldid=prev 2021-12-17T01:45:57Z

<p>Created page with &quot;&#039;&#039;&#039;Repairer:&#039;&#039;&#039; Apocalypse&lt;br&gt; &#039;&#039;&#039;Source:&#039;&#039;&#039; [https://web.archive.org/web/20191230200659/http://arcadefixer.blogspot.com/2017/02/ Power Spikes - Video System 1991 (repair log)...&quot;</p> <p><b>New page</b></p><div>&#039;&#039;&#039;Repairer:&#039;&#039;&#039; Apocalypse&lt;br&gt;<br /> &#039;&#039;&#039;Source:&#039;&#039;&#039; [https://web.archive.org/web/20191230200659/http://arcadefixer.blogspot.com/2017/02/ Power Spikes - Video System 1991 (repair log)]&lt;br&gt;<br /> The game works but with no sound.&lt;br&gt;<br /> Searching on the web, I found a guy who had 2 copies of the game with the same symptoms. He changed the Z80 (CPU used for audio) with no success.&lt;br&gt;<br /> That&#039;s what put me on the wrong way...&lt;br&gt;<br /> <br /> I saw that one of the data lines was stuck high and that the Z80 CPU had an active interrupt (NMI = Non Maskable Interrupt, which can be a cause or a consequence with multiple scenario that can lead to it, thus I wasn&#039;t too worried).<br /> I dumped the audio ROM and it was identical to the MAME romset.&lt;br&gt;<br /> I pulled the audio RAM and it turned out to be good on my programmer.&lt;br&gt;<br /> Following the trace I found it was connected to one of the inputs of a LS174. I went further and I found it&#039;s also connected to one of the outputs of a LS374. The D signal was alive but the output (latched) was stuck high. Other latches of the same IC were working fine so I pulled it. And it was OK on my programmer... I pulled the LS174 cause sometimes even an input can be internally stuck high (quite rare though). It was OK too.&lt;br&gt;<br /> Without the LS374, LS174, audio RAM, audio and audio ROM installed (now all on sockets) the signal was still stuck high.&lt;br&gt;<br /> The only component left was the Z80. I pulled it, replaced it and the sound reappeared magically!&lt;br&gt;<br /> [[File:ApocPS_1.JPG]]&lt;br&gt;<br /> [[File:ApocPS_2.JPG]]&lt;br&gt;<br /> Game fixed.&lt;br&gt;<br /> <br /> ps: I was a bit silly to think it couldn&#039;t be the Z80 because it wasn&#039;t the case twice for the same guy. There are so many parts on our precious board possibilities are almost infinite.<br /> <br /> [[Category:Repair Logs]]</div>

Davewellington