🙂 Brings back memories. Many a 10p shoved in that machine in my early teens back in the day. Like the pinball business, video game developers seem to have lost the art of simple but addictive. EM Pinball was always my thing and now I'm middle aged, I'm the proud owner of a small collection of my favourite Gottliebs, but I still wouldn't mind a missile command or centipede! 😀
I really need to get one of those Fluke units. I have a Centipede board that's got me stumped, with similar symptoms. The logic probe and scope just don't cut it for stuff like this.
Hi James, Johnny Beresford sent me a link to your You Tube site. Very interesting to see how your Fluke Analyser works, and the proper method of mending these games units. Very nice tidy well organised workshop with good access to schematics and bus data etc. Nice to finally see what you do. Hope you manage to source or build a Fluke pod & that the info I sent you from my ex colleague Charles was useful. Best regards - Dave
Hi Dave, not built one yet although I did look inside one and I found an article online where someone had built a similar device with an arduino. It actually might be simpler to build an entire modern unit rather than engineer a pod and use a PC to drive it. Something I'll be looking into.
Great job! Other purpose of watchdog is to deal with any bugs in the ROM code that they might not have fixed in development. ie. on the off chance that there's a hard to recreate bug that locks the system up it will recover via a reset. Watchdogs are commonly used in safety critical applications as well - aviation systems etc. I wonder if the short cause the CPU failure! Very interesting repair!
Thanks for the video. I have a centipede game and all is working except can't figure out why the high score will not save. Can't find any battery inside to replace. any help would be appreciated.
Bad EAROM or circuit going towards it, needs a -27v power rail that gets derived from the main power supply - check the schematics. Think someone's made a replacement for these chips now.
@@retrogamesparty was but the state machine is a PROM chip that is a look up table doing what? and what are the vector register files IC LS670 chips doing?
I think it would have taken a while without it. I'm not sure where you start. It would likely have been my last resort and I'd have checked it from the CPU outwards after everything else. The short is misleading but accessing rom regions outside the lower address lines would still have worked so the /ROMx signals would likely have still been working. Can't say for sure but I'll be looking into ways to diagnose this.
+Retro Games Party I found a short on the address bus of my SNES using a logic analyzer. It was not fun connecting the 40 connections to the SNES though. Sadly the SNES turned out to have a bad CPU in it (The PLB and I think PLA instructions would cause it to start accessing garbage addresses).
Superb James. Especially as the red box stated the error can give your diagnostic equipment misleading results. On that subject, I was wondering what the unit is under your monitor, or cash register on steroids as I like to think of it. You have probably stated it's proper name before but it's the kids summer holidays down here, and the household chaos is something I didn't want to touch with a ten foot logic probe.
The optical sensor is bad on that axis - assuming the vertical works then the clock signal to the trackball is good and so is voltage as they are shared so the direction signal coming back probably not working because the actual opto is bad.
I have the very identical board and have a question. For some unknown reason, I have no centipede, and the archer is stuck in the bottom of the screen, but, all mushrooms are on the play field, and game plays, and hits count on the score. Any help would be great
Hi buddy, I've sent you a reply back to the email you sent via the website as it was a bit long to cover here. Hope it made sense and let me know if you need more help.
They're pretty much all the same - just search logic chip tester on eBay - just remember they can't do everything but they can usually check the 74 series and a lot of the CMOS chips for you.
Hi I’m completely new to anything with arcades but recently picked up some 81 models for MS PAC-Man Centipede and frogger sega cocktail. Turned on centipede and red light on cpu board lights up and the monitor has a white screen ? Any help would be greatly appreciated
Hi All, Great vid... Can anyone help : I have a centipede board that I have corrected several faults and have managed to get it running well. The only fault I have is no sound ! I have checked LM324 and this seems good. I have changed the pokey c012294-01 for a new old stock c012294b-01 but still no sound. I have changed the pokey to another new old stock c012294b-01 and still no sound. I have probed pin 37 on the pokey and nothing. I have even lifted pin 37 but still nothing. I have checked there is data on D0-D7, A0-A3 and RW Q2. Im not so sure about signals on CS low and CS high. Anyone have any ideas. Many Thanks Rick
Hi Rick, I don't have a centipede schematic to hand right now but the CS signal means "CHIP SELECT" generally if the chip has a /CS it means that the chip will be active when the signal on the CS pin is in the LOW state - so you should be observing that pin on a logic probe or scope when sounds should be being made. Also check the voltage input and ground pins in case something has become bad there (ie bad trace on the board). With sound if there's nothing at all, I always start at the end of the circuit and work backwards. Sounds like you've done this and gotten back to the POKEY chip. Observe the activity of outputs on a chip, if nothing, then go to the inputs and check for how its supposed to be used. If I remember right, the POKEY also needs a clock signal of some type - I could be wrong there. If that's not present (if required) then you will get no sound.
very cool. nice to see stuff get fixed and see it come alive on screen.
🙂 Brings back memories. Many a 10p shoved in that machine in my early teens back in the day. Like the pinball business, video game developers seem to have lost the art of simple but addictive. EM Pinball was always my thing and now I'm middle aged, I'm the proud owner of a small collection of my favourite Gottliebs, but I still wouldn't mind a missile command or centipede! 😀
Love your PCB repairs! Thanks for sharing.
Brian Birkinbine You're welcome, I hope they help you if you have things to sort out or they in any way help with electronics or circuit design.
I really need to get one of those Fluke units. I have a Centipede board that's got me stumped, with similar symptoms. The logic probe and scope just don't cut it for stuff like this.
Love your videos and watching you figure out what the problem is..
Keep them coming.
Thanks
Bryan Roth Thanks Bryan, there's plenty more to come :)
Hi James, Johnny Beresford sent me a link to your You Tube site. Very interesting to see how your Fluke Analyser works, and the proper method of mending these games units. Very nice tidy well organised workshop with good access to schematics and bus data etc. Nice to finally see what you do. Hope you manage to source or build a Fluke pod & that the info I sent you from my ex colleague Charles was useful. Best regards - Dave
Hi Dave, not built one yet although I did look inside one and I found an article online where someone had built a similar device with an arduino. It actually might be simpler to build an entire modern unit rather than engineer a pod and use a PC to drive it. Something I'll be looking into.
Hope the spooky warehouse turns out to yield some mint finds, a nice defender :)
Hehe :) Oh yes, the "spooky warehouse". I'll be doing a tell-all very soon. I might have a Defender for sale soon.
great work as usual :)
good job!
Great job! Other purpose of watchdog is to deal with any bugs in the ROM code that they might not have fixed in development. ie. on the off chance that there's a hard to recreate bug that locks the system up it will recover via a reset. Watchdogs are commonly used in safety critical applications as well - aviation systems etc.
I wonder if the short cause the CPU failure! Very interesting repair!
Never thought of it like that, also didn't know about use in aviation systems but makes sense. Thanks for watching and the knowledge.
Thanks for the video. I have a centipede game and all is working except can't figure out why the high score will not save. Can't find any battery inside to replace. any help would be appreciated.
Bad EAROM or circuit going towards it, needs a -27v power rail that gets derived from the main power supply - check the schematics. Think someone's made a replacement for these chips now.
RETRO GAMES PARTY///
,, vector games have register files LS670 chips. What does these Register Files IC chips do in vector arcade games?
Usually part of the state machine - not delved into it that far but seen them in the circuit.
@@retrogamesparty was but the state machine is a PROM chip that is a look up table doing what? and what are the vector register files IC LS670 chips doing?
@@billwilliams6338 absolutely no idea whatsoever - i've not delved into the minutia that far.
Great work :-)
Great video, thank you for sharing you knowledge. I have a few games and you are a great resource.
Another awesome vid! Do you think you would have found the short without the fluke? Cheers.
I think it would have taken a while without it. I'm not sure where you start. It would likely have been my last resort and I'd have checked it from the CPU outwards after everything else. The short is misleading but accessing rom regions outside the lower address lines would still have worked so the /ROMx signals would likely have still been working. Can't say for sure but I'll be looking into ways to diagnose this.
+Retro Games Party I found a short on the address bus of my SNES using a logic analyzer. It was not fun connecting the 40 connections to the SNES though. Sadly the SNES turned out to have a bad CPU in it (The PLB and I think PLA instructions would cause it to start accessing garbage addresses).
Spot on lad!!
Awesome! Centipede is saved :D Keep up the good work!
Thank you. I enjoy doing this, it's sometimes very frustrating but very rewarding
Superb James. Especially as the red box stated the error can give your diagnostic equipment misleading results. On that subject, I was wondering what the unit is under your monitor, or cash register on steroids as I like to think of it. You have probably stated it's proper name before but it's the kids summer holidays down here, and the household chaos is something I didn't want to touch with a ten foot logic probe.
Awesome... on mine sounds comes on and go off. Does not stay on. Any ideas?
I like the video's keep them coming and all the detail's Thank you
Michael B No Apostrophes.
Thanks for video. I replaced my track ball and it still seems not to respond correctly. It will not go right to left and vice versa. Any ideas?
The optical sensor is bad on that axis - assuming the vertical works then the clock signal to the trackball is good and so is voltage as they are shared so the direction signal coming back probably not working because the actual opto is bad.
@@retrogamesparty Thank you! Ill try it.
I have the very identical board and have a question. For some unknown reason, I have no centipede, and the archer is stuck in the bottom of the screen, but, all mushrooms are on the play field, and game plays, and hits count on the score. Any help would be great
Hi buddy, I've sent you a reply back to the email you sent via the website as it was a bit long to cover here. Hope it made sense and let me know if you need more help.
Great video! Super interesting work. For someone just getting into arcade board repair, what chip tester do you recommend?
They're pretty much all the same - just search logic chip tester on eBay - just remember they can't do everything but they can usually check the 74 series and a lot of the CMOS chips for you.
Hi I’m completely new to anything with arcades but recently picked up some 81 models for MS PAC-Man Centipede and frogger sega cocktail. Turned on centipede and red light on cpu board lights up and the monitor has a white screen ? Any help would be greatly appreciated
Nice scope man ;)
I’m watching repair videos whilst repairing a tacscan board :-)
Hi All,
Great vid...
Can anyone help : I have a centipede board that I have corrected several faults and have managed to get it running well. The only fault I have is no sound ! I have checked LM324 and this seems good. I have changed the pokey c012294-01 for a new old stock c012294b-01 but still no sound. I have changed the pokey to another new old stock c012294b-01 and still no sound. I have probed pin 37 on the pokey and nothing. I have even lifted pin 37 but still nothing. I have checked there is data on D0-D7, A0-A3 and RW Q2. Im not so sure about signals on CS low and CS high. Anyone have any ideas.
Many Thanks Rick
Hi Rick, I don't have a centipede schematic to hand right now but the CS signal means "CHIP SELECT" generally if the chip has a /CS it means that the chip will be active when the signal on the CS pin is in the LOW state - so you should be observing that pin on a logic probe or scope when sounds should be being made. Also check the voltage input and ground pins in case something has become bad there (ie bad trace on the board).
With sound if there's nothing at all, I always start at the end of the circuit and work backwards. Sounds like you've done this and gotten back to the POKEY chip.
Observe the activity of outputs on a chip, if nothing, then go to the inputs and check for how its supposed to be used.
If I remember right, the POKEY also needs a clock signal of some type - I could be wrong there. If that's not present (if required) then you will get no sound.