https://wiki.arcadeotaku.com/index.php?action=history&feed=atom&title=Chelnov_Repair_Logs 2026-05-24T05:44:27Z Revision history for this page on the wiki MediaWiki 1.42.1 https://wiki.arcadeotaku.com/index.php?title=Chelnov_Repair_Logs&diff=15087&oldid=prev 2022-01-06T23:50:23Z

<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/20191230200638/http://arcadefixer.blogspot.com/2017/12/ Chelnov/Atomic Runner - Data East 1988 (repai...&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/20191230200638/http://arcadefixer.blogspot.com/2017/12/ Chelnov/Atomic Runner - Data East 1988 (repair log)]&lt;br&gt;<br /> <br /> Some repairers have what they call a &quot;too hard to repair&quot; pile. I don&#039;t understand this concept, to me boards are either repairable or not.&lt;br&gt;<br /> Not repairable means a custom chip is faulty (so far I&#039;ve always found a solution to circumvent faulty security chips).&lt;br&gt;<br /> Instead I have a &quot;too long to repair&quot; pile. In this pile you find boards I know I can repair but requiring a lot of time.&lt;br&gt;<br /> This Chelnov board was one of them.&lt;br&gt;<br /> [[File:ApocCAR_01.JPG]]&lt;br&gt;<br /> [[File:ApocCAR_02.JPG]]&lt;br&gt;<br /> <br /> First I swapped all the ROMs, PROMs and security chip on a Karnov board to confirm they were ok. Test was sucessful (meaning all ROMs, PROMs and security chip were good).&lt;br&gt;<br /> <br /> Then I started to repair the bottom board as it contains the only custom chip of the boardset, possibly being a repair killer.&lt;br&gt;<br /> The game was victim of the Fujitsu plague: I removed and replaced all Fujitsu TTL chips of the bottom board (only 5 of them) and then tested the board with the Karnov top board: it was now fully working.&lt;br&gt;<br /> <br /> This is where I left the repair for one year and a half. At this point I knew I could fix the board as all the ROMs, PROMs and security chip were tested OK, so as the only custom chip on the bottom board. I was left with a top board heavily populated with Fujitsu TTL chips and by probing few of them I could tell the damage was extensive...&lt;br&gt;<br /> <br /> When I got back to it I moved on the top board with the same treatment: I pulled all the Fujitsu TTL chips (probably 80+).&lt;br&gt;<br /> This took me several hours... (remember &quot;too long to repair&quot;).&lt;br&gt;<br /> Out of curiosity I tested them on my programmer and 52 turned out to be bad...&lt;br&gt;<br /> <br /> Ok, after that game was still dead, showing only a garbage screen.&lt;br&gt;<br /> I found reset signal of the main CPU was too low to be considered as being a high level (below 3V): 68k was faulty and probably partially grounding/dragging down the signal.&lt;br&gt;<br /> I installed a new 68k, reset signal was now healthy but behaviour of the game didn&#039;t changed.&lt;br&gt;<br /> <br /> So I started to probe the data signal of the main CPU and found there was activity only for a fraction of second after power up.&lt;br&gt;<br /> To me this was a problem with code execution. All the TTL on buses were new now so I checked traces between the program ROMs and RAMs but they were all OK.&lt;br&gt;<br /> Last probable culprits in line were the work RAMs, unfortunately activity didn&#039;t last long enough to see anything on my old analog scope.&lt;br&gt;<br /> So I pulled them and both revealed bad on my programmer. Once replaced the game booted!&lt;br&gt;<br /> [[File:ApocCAR_03.jpeg]]&lt;br&gt;<br /> [[File:ApocCAR_04.JPG]]&lt;br&gt;<br /> <br /> With sound, controls, texts and background but sprites were totally absent.&lt;br&gt;<br /> Probing TTL chips I found the outputs of the only 7425 (Texas Instruments) on the board were floating: sure enough it was bad.&lt;br&gt;<br /> I replaced it and finally obtained a fully working game.&lt;br&gt;<br /> <br /> [[File:ApocCAR_05.JPG]]&lt;br&gt;<br /> <br /> Game fixed.&lt;br&gt;<br /> [[File:ApocCAR_06.JPG]]&lt;br&gt;<br /> <br /> - 1 * CPU 68000&lt;br&gt;<br /> - 2 * work RAMs (6264 type)&lt;br&gt;<br /> - 1 * LS08 (Fujitsu)&lt;br&gt;<br /> - 2 * LS10 (Fujitsu)&lt;br&gt;<br /> - 1 * LS30 (Fujitsu)&lt;br&gt;<br /> - 3 * LS32 (Fujitsu)&lt;br&gt;<br /> - 6 * LS74 (Fujitsu)&lt;br&gt;<br /> - 1 * LS125 (Fujitsu)&lt;br&gt;<br /> - 1 * LS138 (Fujitsu)&lt;br&gt;<br /> - 9 * LS153 (Fujitsu)&lt;br&gt;<br /> - 7 * LS157 (Fujitsu)&lt;br&gt;<br /> - 1 * LS174 (Fujitsu)&lt;br&gt;<br /> - 3 * LS194 (Fujitsu)&lt;br&gt;<br /> - 11 * LS245 (Fujitsu)&lt;br&gt;<br /> - 4 * LS283 (Fujitsu)&lt;br&gt;<br /> - 2 * LS374 (Fujitsu)&lt;br&gt;<br /> - 1 * 7425 (Texas Instruments)&lt;br&gt;<br /> [[Category:Repair Logs]]</div>

Davewellington