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Lama Himself

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Everything posted by Lama Himself

  1. ok, so I finally got some RAM chips ans sockets to be able to replace them later on if necessary. I also measured somes voltages: - The voltage of the board is ok since I measured exactly +5.0V - For the RAM chips it's different. The +5V and +12V varies but usually stay in the tolerated range (+-10%), however the -5V are often around -5.7V, -5.8V. I will change the chips anyway since the test mode tells me they are bad but should I worry that this bad voltage could be caused by something else on the board? If yes, how do I track that? Thanks for your help!
  2. And where did you get your replacement RAM sdamon? I'm fine to use other RAM chip (I'm sure the board have some tolerance) if it's working but I doubt I can just take any 16K RAM. yeah the soldering can be challenging. I'm not an expert (far from it) but I already done some really precise soldering on modern consoles (no, not modchip). But my goal is really to repair it myself. Oh and I live in Germany and I don't know any repair shop here.
  3. Thanks for your quick reply Rybags. The TMS4116-20NL chip is a 16K RAM chip. I don't think it's especially rare. It's probably easier to find them than using a daughter board. I've downloaded already the manual of Missile Command: www.mamext.net/manuali/missile.pdf But I don't recall any indication on how to manually test ICs.
  4. Hi, I got my hands on a cocktail table with Missile Command few months ago. The previous owner said the game used to work but unfortunately the game doesn't seem to work for me. This is the first time I will repair an arcade so I come here maybe to get some tips and wisdom My overall goal for the repair is not really the look of the arcade (the leg would need a refreshment for example, and there is scratches here and there)., but more the game itself. So the board should run and I want the control to feel good (so some work on the bearing, maybe polishing the trackball). After running the test mode it seems that I have a problem with the RAM. I have 8 high pitch beeps so it would mean that all the 8 RAM chip are dead. So the next step for me would be to buy replacement chips. So I'm looking for the chip reference TMS4116-20NL. There is some sellers on internet but the minimum orders are often too high, made for professionals. I also found this page http://4sale.sbszoo.com/but it seems it's used chip only. I don't really mind the 20$ minimum order if I can get my hands on this RAM chips. Is anybody have experience buying such chip? Do you have any advice or good addresses? Do you also know any reason why all the RAM chip would die? I plan to check the voltage, but maybe there is an other problem somewhere? Anyway, thank you in advance for any help you could provide.
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