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Womble

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Everything posted by Womble

  1. I think the damage stems from any system that squirts out an SVGA signal while it boots through the BIOS and into the OS, before the emulator kicks in and tones the video output down to 15Khz CGA. So I'd suggest that any system which is basically a PC will do this, and anything that is just a multi game PCB that doesn't need an external ATX PSU would be safe. Not 100% on that tho.
  2. If the power supply voltages are correct then it’s probably either... 1) Fujitsu TTL rot, these chips are dropping like flies from old age, whether used or not the internal bond wires oxidize and fracture leaving the internal chip disconnected from the outside world. or 2) Custom IC leg rot - these ICs had legs that were silver plated tin, over 35 years the two metals have reacted causing the legs to weaken to the point of fracture, the surface layer of silver has also reacted with the atmosphere and turned black. People think the black colour means they are a bad contact but actually the oxide is highly conductive, its just that the legs are often fractured inside the socket and no longer connected. Basically it is old age, these things often die on the shelf.
  3. Could be a range of things, the RAM and ROM tests on these boards aren't that intensive (the mask ROM tests are better but not infallible). I'd suspect a logic issue somewhere, or an open track, both quite common with Konami gear.
  4. The schematics suggest they are 4.7kohm http://www.jammajup.co.uk/manuals/chase-hq-schematic.pdf
  5. First thing to do is always check the voltages at the board, confirm you are getting 5V at the PCB, not just at the PSU. Second thing I would do is to reseat the daughterboards. They are the small PCBs plugged into the main PCBs, usually they are rammed into standard PCB sockets which don't like the wider pins. They cause all sorts of issues due to oxide build up, but removing them and reinserting scrapes the oxide away and cures the bad contact. You may find your gfx issues disappear when you have reseated them. Be very careful to line up the pins correctly when you re-install them. The transformer and wonky chip won’t be causing your issues, both have been that way since the day it was made.
  6. If you do decide to replace it please be careful. Sega used the reverse colour scheme for their wiring. Everyone else... Red = 5 volts Yellow = 12 volts Black = Ground Sega.... Yellow = 5volts Red = 12volts White = Ground Many Sega boards have been sent to Arcade heaven by people squirting 12v up the yellow wires.
  7. Awesome! Good work. Yes, I was asking if they were all one set. The program ROMs all have to be the same set or the CPU won't boot, but you can end up with mixed GFX ROMs which would mean the board is throwing around the wrong gfx data, so things will look strange, or almost perfect in some areas.
  8. For stuff like that you really need to get a Fluke 9010 hooked up to it. That would let you test the RAM and ROM, and by definition the glue logic, as if you were a CPU plugged into the board. Something that the CPU doesn’t touch until level 5 is going to be almost impossible to troubleshoot with even a logic probe.
  9. They can, if they have lost the ability to turn off their output pins based on what their output enable pin is doing. A CPU needs the ability to read from anywhere in it's memory map, which will contain some RAM and ROM, and this is rarely in one chip, so the pcb logic decodes the pattern of bits put on the wire by the CPU and selects the correct IC (or a pair in 16bit systems) of RAM or ROM. If the board is behaving then only one RAM, or ROM will be enabled (using the /OE pin) at any given time, and all the others need to go into high impedance mode, where they don't put anything on their data pins, despite them getting all the address signals in on that bus. ROMs also have a /E enable pin, that puts them in low power shut down, that tends to be unused on arcade boards as it takes longer to wake up. When the ROM is on a burner it doesn't have to play nice with anything else, so /E and /OE functions are untested. Are you sure in your case that all the ROMs were from a single set?
  10. That's a really weird one, do you have a logic probe or an oscilloscope? I'd be taking a look at the address decoding logic for a fault like that.
  11. Address to output delay is just a fancy way of saying "read speed", the time gap between an address being presented at the address bus, and the relevant byte appearing on the data bus. Give them a go, its highly likely they will work fine, just check you can get the data sheet on them, and that they don't need something silly like 21V to program. A lot of cheap programmers can't up to that voltage. For the original ICs in your burner app ....12.7v is fine, everything has a range, 12.7 is at the safer end, and they probably go low in case the programmer also has a 10% variance. 2.75v - 13v Nominal - 13.25v
  12. You should be fine, the JL isn't significant here, but the datasheet is always worth a look if you are unsure about the part codes https://pdf1.alldatasheet.com/datash...TMS27C256.html Most chip IDs consist of a few parts, and the letters at the far end usually just denote the package type or some other environmental specification, but not always. AMD went through a period where the end codes really did matter, with chips like 27c256AD, 27C256ADC, 27c256DC, where the VPP changes between 12, and 21V, within the same part number. In this case the JL just defines the temperature range the chip can deal with. In other cases those codes may denote the package type, or whether it's a medical or military grade part, which you never find on arcade boards, as every possible expense was usually spared. Based on the datasheet the VPP for the TMS27C256xxx family is 13volts, your programming application should display the VPP when you select a chip, its always wise to confirm it is what you are expecting, before you press the detonate button. Not much happens if you over voltage a chip, the write attempt will fail and it isn't an EPROM anymore. The rest of the code... TMS=Texas Instruments manufacturer suffix 27 = Series 27 chips, ie Industry standard EPROMs at this time (there was a platform war between series 25 and 27 for a while by that died out long before chips got to this capacity. Series 27 won out and became the standard by the time chips hit 64kbit capacities. C=CMOS family (in most cases this means the chip has a quartz window - a very expensive part - P here means no window so you can never erase, but the guts are the same. 256= Size in kilobits JL= 0-70 degree C operating range.
  13. Every Outrun board I've met recently has been brutalisd,with machined-pin SIP strips fitted as sockets for replacement RAM. The pins are so fat the solder doesn't fill the holes and in some cases they are hammered in so hard they break the plate through hole. Takes hours to get them off without causing more damage. I have had 5 in the last 18 months, and they all seem to have been through the same guys hands. I really wish Jaycar didn't stock machined pin strips or sockets, it encourages people who don't know what they are doing to "upgrade" their repair, which fails in some cases due to the socket itself. The margin on those sockets must be a real money spinner over the dual wipes.
  14. Yep, you have a dead EPROM, if it gives you a different read each time then it is 100% kaput (unless it is a really weird type, and/or you are trying to read it too fast - which isn't the case here). When you get the new ones, make sure you have the exact type set in the burner software, make and exact model number. Almost all ROMs types are interchangeable in the reader software when you are just trying to read them, but you need to get the exact one configured when you are writing. Not just due to the timing requirements, but mainly because the programming voltages can vary amongst manufacturers, anything from 12V to 21V. Too low and it probably will fail midway through, too high and you can kill the chip instantly. Some ICs actually have the programming voltage (VPP) written on them, its always worth checking that the burner software has the same voltage configured. Sorry if that's obvious, but it catches people out from time to time, as they blast through their new batch thinking they are all DOA.
  15. Usually the file name will contain a clue as to the location of the ROM it came from, often the filename suffix will be the grid location eg, something.7a Its harder if you have a bootleg as they often don't have the silkscreen locations on the board, so you may just have something.7. I've had to resort to google images before to find what the original ROMS were labelled. On some boards the bootleg ROMs are just labelled 1 through 18 with no reference to their actual location. In some cases you can upload the file you find in a .zip into an online tool and get a more useful filename match than the one it came with. If the board had no ROMS onboard at all then then you have to resort to asking on forums whether people recognize the PCB, you'd be amazed that you often get right answer. Its all a bit messy I'm afraid.
  16. Hi George - Yep I'm still around, 11 years ago sheesh! The simplest way is to take a read of one the ROMs on board and put the resulting .bin file into this site http://romident.coinopflorida.com/ That will tell you the parent set, which you then track down and extract to find the corresponding bin for ROM 17. However for graphics elements the data is usually the same between sets, so any MAME zip for Rastan would likely have the same data as any other versions.
  17. Nope, it’s the cheap harness. Those modern ones are only intended for the modern x-in-1 boards that take a tiny amount of current, or for the PC based ones that use an external ATX power supply and so don't rely on the harness itself to deliver power. If you use them with an original board they can't deliver the current the board tries to draw as the wiring is too puny, the result is voltage drop. I don't believe there are any good sources for quality harnesses these days, as the cheap ones will outsell the expensive ones 100 times to 1, wven ads that state they have decent wires are just the same old Chinese crap in the photo. Even ones that look like thicker wire on the power rails often only have thicker insulation, there's no more actual copper in them. Your best bet is to replace the 5V and the ground wires with thicker wire, or find someone local who can do it.
  18. Yep, that’s normal. Only the 5v is directly adjustable on arcade PSUs, the others drift relative to the 5, so are almost never bang in their rating, as it depends on the current draw, ie the load on that rail. It also doesn’t matter as the 12v rail is usually only used for the audio amp. The amp ICs are usually happy anywhere from 9 to 21v, in many cases they are actually the amps from car stereos of the era. The amp also puts very little load on the 12v rail so it is often a few volts higher than the nominal 12v. The -5v rail is usually used to negatively bias op-amps so it isn’t critical either. The drop across the board is also fine. If you have a lot of drop between the PSU and the PCB edge connector then your power and ground wires are too thin, but 0.1v drop across a board is pretty good/normal.
  19. No harm at all, if the board doesn’t need it then the pin on the pcb goes nowhere. It’s actually safer to have it wired up, rather than dangling around near the psu, with mains nearby.
  20. Those locks are very easy to pick, you just need a bent pin and a needle and about 10 minutes. You can drill them out but that makes a mess of hot metal shards. I suspect the main access for this cab is through the front, the roof looks like the other way in if you need to get to the monitor, not sure why it is stuck though.
  21. What is the transformer powering? I'm assuming it is just the monitor, which is daft as you don't need a step down for that. As per the sticker on the side it will take anything from 90VAC to 260VAC so you could wire it into the mains directly, I suspect it is just like this as they didn't want to cut the plug off and wire it properly. The only benefit to this set up is you *may* have an isolating effect, but for a JOMAC chassis I don't think you need it, unless you plan to go poking around in it while it is powered on. Not all transformers isolate so that's a guess for that specific one
  22. Looks like an issue with the video ground or sync connection between the monitor and the game board. If you reseat the JAMMA harness to the game board you will likely fix it. Old connectors with old contacts are a common problem as a layer of oxide will build over over the years. After a decade or two the contact is lost, but a reseat will scrape back the contacts and restore the connection. Could also be a similar issue with one of the hold controls on the monitor chassis.
  23. Bizarre timing, my bench 1084 started smoking today. One of the deflection coils has shorted, apparently fairly common as the rubber wedges degrade over time and the result eats the insulation off the windings at the point they are in contact. Looks like the same has happened to yours. Am faced with either scrapping it or attempting to rewind too.
  24. Looks like you have lost either the video ground, or the video sync connection between the board and the monitor. The 1st picture looks my sync'y and the second looks more video groundy. I'd reseat the JAMMA connector first.
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