Old arcade game console. - Page 1
Forum section: electronics / projects

author: GK
author_rank: Super Contributor
timestamp: May 01, 2018, 09:00:25 am
content: A workmate of mine had one of these old table-top arcade game machines that stopped booting properly some time ago. In the end he stripped it out and retrofitted the cabinet with an ebay 100-in-one games board and a modern flat screen. The original innards were gifted to me.Now comes the fun part of identifying the thing, finding schematics and getting it going again. The strange thing is, neither on the original cabinet nor anything else, is there any kind of obvious product identification at all. Three of the EPROMs on the small board had lost their window stickers - I hope ROM erasure wasn't the cause of failure.From what my workmate recalls, it was a single-screen (non-scrolling) game with a gorilla that picks up/collects coconuts.Anyone out there have any idea - vintage/make/game/era/ect ?

author: ebastler
author_rank: Super Contributor
timestamp: May 01, 2018, 09:19:17 am
content: Maybe Amidar?https://www.arcade-museum.com/game_detail.php?game_id=6883https://arcadeclassics.net/80s-game-videos/amidarThe gorilla & coconuts sound right, and the "AMG" labels on the EPROMs kind of fit... But from the scant manual/schematics I can't figure out at first glance how many circuit boards there were supposed to be; and the board layout may not be a full match?EDIT: Or maybe the bootleg version called "Amigo"? Fits the AMG acronym even better.https://www.arcade-museum.com/game_detail.php?game_id=6884If it's that one, documentation and EPROM contents might be harder to come by...

author: GK
author_rank: Super Contributor
timestamp: May 01, 2018, 09:23:22 am
content: Yep, I reckon that's the one! - I googled "Arcade game gorilla coconuts" and found this simultaneously:http://www.gallopingghostarcade.com/qr/amidar/manual.pdfOn initial glance the board layouts and major IC's appear to be a match.

author: GK
author_rank: Super Contributor
timestamp: May 01, 2018, 09:26:20 am
content: Ooh! Found the ROM images too, just in case!http://www.freeroms.com/roms/mame/amidar.htmIsn't the interwebs awesome?

author: ebastler
author_rank: Super Contributor
timestamp: May 01, 2018, 09:29:34 am
content: Quote from: GK on May 01, 2018, 09:26:20 amYep -- imagine how this kind of research would have gone 25 years ago!I'm keeping fingers crossed that the bootleggers did a good job (if it's a bootleg PCB -- the lack of a manufacturer name on the board is ominous), and that "Amidar" and "Amigo" are fully compatible!

author: GK
author_rank: Super Contributor
timestamp: May 01, 2018, 09:34:12 am
content: Quote from: ebastler on May 01, 2018, 09:29:34 am.... and the cabinet with no apparent identification.When I get the time in a day or two I'll pull out and read all of the EPROM chips and run a byte-by-byte "file compare" in my Hex editor with the ROM images I've just downloaded.

author: Wolfram
author_rank: Frequent Contributor
timestamp: May 01, 2018, 09:58:02 am
content: There's a PCB set from an Amigo on eBay, the boards look identical to these.https://www.ebay.com/itm/263646839024?item=263646839024&rmvSB=true

author: Blinkenlights
author_rank: Contributor
timestamp: May 02, 2018, 06:05:47 am
content: You can work out the vintage of the board by the date code on the ICs, seems to be 1981.You should not worry too much about ROMs not having the correct code - that seems to happen rarely.I would suggest a careful visual of the board, checking for abrasions/damage that sort of thing.Treat the board carefully, - bring up the power on a lab power supply with current limit.I would suggest to you that the problem with the board - other than abrasions/damage -is almost certain to be the IC sockets. I would replace all the EPROM sockets and the CPUsocket on the video board (larger one) first - if you are lucky it will then boot. Quite oftenthe games would power up with just the video board operating, allowing the sound board(the top one) to be debugged seperately.It is probably a good idea to replace every IC socket in both boards though, the originalboards were often not produced with good quality sockets. Hope this helps.

author: ebastler
author_rank: Super Contributor
timestamp: May 02, 2018, 06:19:41 am
content: I don‘t think abrasion is a likely cause. According to GK‘s report, the board failed while installed in the cabinet. This is not a board which got tossed around in a warehouse as a bare PCB.Sockets are certainly a suspect. But short of replacing them all, I would start with pulling and re-seating all socketed chips.

author: Blinkenlights
author_rank: Contributor
timestamp: May 02, 2018, 07:25:49 am
content: Quote from: ebastler on May 02, 2018, 06:19:41 amHmm..... I have repaired a few hundred arcade games.My advice as to the best approach stands.I am reminded why I don't post on forums... thanks "ebastler" the ball is in your court with randomly pushing chips in harder and no visual at all...

author: GK
author_rank: Super Contributor
timestamp: May 02, 2018, 08:29:15 am
content: Hmm, OK, I'll definitely be going over the sockets...I now know with certainty that the game is the Amidar bootleg Amigo. I mentioned this first thing to my workmate this morning and his memory was jogged.One thing that is interesting is that the video graphics generation circuitry is all TTL and EPROM/PROM based. Both the video board and the sound board are Z80 based and, with the exception of the AY-3-8910 sound chips, there is nothing here which couldn't be functionally replicated with current production CMOS logic - just as per my PET computer clone.Not that I need another project of this scale or will be embarking on a clone build any time soon though.

author: GK
author_rank: Super Contributor
timestamp: May 02, 2018, 08:32:59 am
content: Quote from: Blinkenlights on May 02, 2018, 07:25:49 amHey, do you know how universally basic board designs like these were applied back in the day? I'm just wondering how game-specific this hardware was back then and if it might be possible to run different games just by plugging in different game ROMs and re-wiring the controls.

author: ebastler
author_rank: Super Contributor
timestamp: May 02, 2018, 09:04:05 am
content: Quote from: Blinkenlights on May 02, 2018, 07:25:49 amOh please, no need to take this personally. My comment was certainly not meant as a personal slight, or doubting your competence.I agree that mechanical damage and abrasion is frequently seen on arcade PCBs. But the damage I have seen was typically due to boards being stacked in storage without any protection. For a board that was installed in its original cab and failed spontaneously, this seems less likely.As mentioned, corroded sockets would be among my prime suspects too. In my experience (based on arcade boards and computers from that era), pulling the chips from the socket and re-inserting them stands a very good chance of re-establishing good contact and solving the problemtemporarily. I recommend doing this first to verify that there is indeed an issue with the sockets. If confirmed, definitely go ahead and exchange the sockets, for long-term stability.

author: ludzinc
author_rank: Unknown
timestamp: May 02, 2018, 09:54:37 am
content: I have an IREM Space Invaders table top.Had video RAM issues, and intermittent booting. Fixed the Video by replacing a RAM chip. Intermittent booting took longer to fix.You guessed it - new EPROM sockets....

author: NivagSwerdna
author_rank: Super Contributor
timestamp: May 02, 2018, 10:43:16 am
content: Pop out a ROM or two... Read them in your trusty EPROM programmer... and then put the checksum intohttp://romident.coinopflorida.com/The way these things normally work is that the top board is the interface to the external world and has sound generation (and small amplifier under the heatsink), the bottom board is video generation and main processor.You need to work out the connector and supply it with the necessary voltages... some boards like yours require +5, -5 and +12, then hook the other end up to a monitor that is capable of 15kHz.First things to check are cpu oscillator and video sync out.Looks very repairable. No custom chips. Z80 for main cpu and another Z80 for sound. The absence of maker marks suggests it could be a clone/bootleg but functionally it will be the same. Repair it for love not money, this is early 1980s only really of interest to those with a mispent youth in the 80s.Have fun!