It was a hint in this repair that allowed me to finally fix the synthesizer I had been struggling with for months. Thanks for all the logic troubleshooting lessons.

Great job on the repair. Also, well done explaining it all. I also repaired a Yie Ar Kung Fu board last year and documented over on the Arcade-Projects forum. It was my first repair and very fun!

Nice job doktorzett 👍. When you found the problem ic, I noticed it was Fujitsu branded. These Fujitsu logic and ram chips seem to be common failure points on arcade boards these days. They've obviously lasted well outside there design spec though, so can't really be that tough on them I suppose. But it just goes to show the quality of these old chips. And the more reliable brands are still going well over 30 years. I don't think today's tech will get anywhere near that level of reliability.

It makes me very happy when I see you've uploaded a new video. Even more so with one of my favorite games! I have this board myself too. Thanks for your amazing explanations, it makes the channel such good quality!

Great repair video! So glad you couldn't use the fluke lol Thank you for going through each troubleshooting step with us!

Another awesome repair!!!!

👍😃 Another excellent repair video. It was obvious on first power up that the board was "watchdogging" but the question was why? After checking the basics of the CPU (power, clock, reset, halt) the fact that there was no activity on the address or data pins immediately pointed to a dead CPU. The 6809 (my favourite 8-bit CPU) fetches its reset vector from FFFEh & FFFFh on power up so there should be some activity on the address and data lines. Unfortunately you then fell foul of the massive market in fake chips from China. I would never have trusted chips that were that cheap and they immediately looked suspect by how shiny the legs were. You tend to get what you pay for. It would be interesting to "delid" one of those fake 6809's to see if there is any silicon in it at all - I suspect not. Fluke 9010A's are rare but 6809 pods for them are even rarer! Your troubleshooting was an excellent example of knowing your test equipment and what it is trying to tell you. The subtle change in brightness between a logic high signal and a floating pin is easy to miss on the logic probe so well done for spotting it and pointing it out so clearly. Tracing the source of the bad signal back to the 74LS32 was a good example of how to use a schematic and then explaining why that chip must be bad by explaining its logic function and the fact that the signals did not correspond to it was very well done. Your reward was a working board - congratulations! 👍😁

As always with your videos, I've learned a lot, thank you.😎

Yes, finding a reliable source for CPU's is challenging. I ordered 20 6809EP's and 9 were bad. Some where not the E version. I use a JROK board (Williams) with a ZIFF socket to test 6809E's in. I also ordered 20 Z80A's and 1 was bad in those. The 6502's I had 4 bad out of the 30. For testing the 6502's I use a Centipede board with a ZIFF socket. The Z80 boards are pretty common so I just use the closest PCB at the time :) I bought the 6809's and Z80 from UTSOURCE and the 6502's from eBay. The eBay seller just sent me replacements. The UTSOURCE wanted the bad ones shipped back, which would have cost more so I just ate the cost of the bad ones.

Nice repair video!

Enjoyed this, thanks!

Nice one. You should erally upload way more often! Not once in a blue moon.

Hi doktorzett, as usual this was a very nice video! You might want to get a NOP-tester for future repairs.That device could have shown you easily that the CPUs are bad. Do you happen to know why the markings on the KONAMI ASICs are milled out?

Nice video. Dodgy Alibaba chips? Could you tell us more about your test rig, the connectors and adapter, power supply etc?

Very interesting repair as usual. I've been lucky so far. A couple fake Eproms were all that I had to chew. And those were even repainted but working equivalents. You could try to crack open one of your fakes and look at the die under a microscope to see what they've really sent you. Aren't you curious?

Very nice, when is the next video?😁

Hi! maybe you can help me: I have two Arkanoid pcbs, one "tayto" bootleg, and another Beta bootleg... the "tayto" bootleg has the normal sound pitch like the original Taito pcb, but the Beta bootleg has the sound pitch too high...is there any way to fix this (make beta bootleg sound pitch normal)??

Hey @doktorzett I love your logic probe. I’m gonna pick up the same one. I noticed the ends are like plugs. Is it ok to replace those with alligator clips? I think that’s what you’ve done with yours but I just wanted to confirm. Thanks!

bad away nice work

we talked about that. i have super breakout that resting. EPROM o.k by reader. without fluke how can caeck communication with cpu? ram etc eed fluke and logic analysis. with logic probe i dont get anything

how logiv probe know if Data correct?

I got burnt from ebay with some 8080 cpus so after that i will never bother buying from there again,

enough with chips Chinese ic just Europe or us ic