Awesome. 30 years as an arcade tech myself, and watched a bunch of your videos, and no one ever showed me how to use a logic probe, so I wanted to teach myself and bought one, but never used it. Recently while expanding my knowledge on the science behind electronics, and learned about how boards read code and about exactly how a clock pulse can be made with transistors and capacitors, and HI and LOW
Well done on the repair. I'm sure it took way longer than assumed by warching this video. So nice to see original Arcade PCBs being saved from the landfill!
Stern games in general had horrible power supplies. Also the early z-80 processors marked Italy were defective. Change to a switching power supply replace the processor to Z80a And most of your problems will disappear. This guy does a great job explaining trouble shooting. Remember the only two things you can do with electricity is switch and regulate.
I might be barking, but I think the first section of the circuit is a "brown out detect" circuit (looks for a voltage drop/dip on the base via the 470 ohm resistor, and the 220uf holds an average of the supply voltage). When you get a psu brown out, this then causes the pnp transistor to conduct which then sends the voltage at 220uf (as that's not dipped you see and its a fairly big value to sustain enough power while the psu is low) , to turn the 2nd transitor on... this discharges the 10uf capacitor which is the main power on reset circuit, causing a reset if it dips long enough.. The rest is just a normal reset circuit, which is the 10k resistor and the 10uf cap.... this starts at 0v and then charges up to 5v over time, causing 5c output to start at 1 and then go to 0.... Thats combined with what looks like a watch dog at 4d, If the power supply is dipping from time to time it will cause a just in case reset....
Its such a long time back, I think because I was poking around in effectively an analog part of the circuit I could tell what was going on. This was before I learned how to use a scope properly and about proper logic hi/lo/floating. I would use a scope for this kind of repair nowadays and use trigger capture and so on or two probes at once etc. Ok, i'm hiding the fact that when this was done I knew very little - I don't claim to know everything now but certainly a lot more than I did back then.
its a "logic probe", The tip (probe) in the guy's hand is only part of the device. It is an equipment that can be very useful for an electronic engineer or technician but that is useless for those who do not have the necessary technical conformation.
Yep, well spotted :) I had to order specially one that had an A and a B drive as all the other ones I had lurking around were the standard you get now with motherboards which have only 1 drive and a twist at the end. I did try to rework a newer one but couldn't get it to re-crimp properly.
I'm not sure but ,if anyone else wants to learn about how to repair my computer try Saankramer Electronic Magazine System (just google it ) ? Ive heard some extraordinary things about it and my co-worker got excellent results with it.
jejeje I laught when the prove slipped from pin #26 and join two pins together... and you suddenly stressed!!!!, happened me 1000 times, but z80's are inmortal.
Awesome. 30 years as an arcade tech myself, and watched a bunch of your videos, and no one ever showed me how to use a logic probe, so I wanted to teach myself and bought one, but never used it. Recently while expanding my knowledge on the science behind electronics, and learned about how boards read code and about exactly how a clock pulse can be made with transistors and capacitors, and HI and LOW
Well done on the repair. I'm sure it took way longer than assumed by warching this video. So nice to see original Arcade PCBs being saved from the landfill!
Stern games in general had horrible power supplies. Also the early z-80 processors marked Italy were defective. Change to a switching power supply replace the processor to Z80a And most of your problems will disappear. This guy does a great job explaining trouble shooting. Remember the only two things you can do with electricity is switch and regulate.
I might be barking, but I think the first section of the circuit is a "brown out detect" circuit (looks for a voltage drop/dip on the base via the 470 ohm resistor, and the 220uf holds an average of the supply voltage). When you get a psu brown out, this then causes the pnp transistor to conduct which then sends the voltage at 220uf (as that's not dipped you see and its a fairly big value to sustain enough power while the psu is low) , to turn the 2nd transitor on... this discharges the 10uf capacitor which is the main power on reset circuit, causing a reset if it dips long enough..
The rest is just a normal reset circuit, which is the 10k resistor and the 10uf cap.... this starts at 0v and then charges up to 5v over time, causing 5c output to start at 1 and then go to 0.... Thats combined with what looks like a watch dog at 4d, If the power supply is dipping from time to time it will cause a just in case reset....
Love this channel, been ages since i repaired a board but must get into it again......on search for cheap board LOL
Great video. Very informative.
I know an old video but do you have any videos on setting up arcade pcb to a lcd monitor? Many thanks
good
nice bit of work mate im learning
Excellent video, thanks for the troubleshooting info
nice video. any reason you have your probe set to cmos?
Its such a long time back, I think because I was poking around in effectively an analog part of the circuit I could tell what was going on. This was before I learned how to use a scope properly and about proper logic hi/lo/floating. I would use a scope for this kind of repair nowadays and use trigger capture and so on or two probes at once etc.
Ok, i'm hiding the fact that when this was done I knew very little - I don't claim to know everything now but certainly a lot more than I did back then.
cold solder joints are a problems with these logic boards.
What tool are you using and what brand is it? Thanks for sharing! Cheers.
its a "logic probe", The tip (probe) in the guy's hand is only part of the device. It is an equipment that can be very useful for an electronic engineer or technician but that is useless for those who do not have the necessary technical conformation.
good video thankyou for making it
9:31 what is that 60Hz buzz I'm hearing?
the component near the afr is the hard switch fo reset?
somebody know?
Is that an old FDD cable you're using to extend?
Yep, well spotted :) I had to order specially one that had an A and a B drive as all the other ones I had lurking around were the standard you get now with motherboards which have only 1 drive and a twist at the end. I did try to rework a newer one but couldn't get it to re-crimp properly.
Love the channel already! Subbed! =)
Thank you, plenty more to come.
I'm not sure but ,if anyone else wants to learn about
how to repair my computer
try Saankramer Electronic Magazine System (just google it ) ? Ive heard some extraordinary things about it and my co-worker got excellent results with it.
be careful with your logic probe you have it on CMOS setting.
You in cmos function in the prob
jejeje I laught when the prove slipped from pin #26 and join two pins together... and you suddenly stressed!!!!, happened me 1000 times, but z80's are inmortal.