Awesome John, congrats on getting Tempest up & going. I love Phoenix, it's one of my favorites in my collection, as I played it a lot back in the day. By the way this is Greg, the guy you met at Cax last July as I was rolling in my Phoenix cab.:)
Hi, John. ;) 15:40 (ish) - When you're testing diodes in-circuit, you will very often get that "counting up" of the value on the meter, especially in the diode test mode. This is usually due to capacitance in the same part of the circuit. Also, the "OL" on the meter actually means "OverLimit", or basically the reading has gone out-of-range for the meter. (apparently, it's called "Open-Loop" in other modes, which is news to me. lol) It's important to remember that the reading in Diode mode actually shows the forward-voltage drop across the diode, and not the resistance. The diode mode is needed because the meter then puts a slightly higher current through the diode (although still very low current of tens of milliamps usually). The meter also puts a higher enough voltage across the diode to activate the junction itself, so the voltage should pass when the red meter probe is on the anode (the side of the diode without the stripe). (again that voltage is quite low though, only a couple of volts on most meters. It just has to be enough to overcome the usual 0.5-0.7 forward-voltage of the average diode.) It looks like those two big diodes are fine tbh. Another thing which causes the weird reasons is because the current from the meter, although low, can charge up the capacitors and other devices on the board, so when you go to swap the probes over, it will often show that weird stuff again. The only real way to properly test most stuff is to remove it from the board, or to lift one of the legs if it's only a two-pin device. Testing them in-circuit like this is usually OK for things like big rectifier diodes etc. though. Watching the rest of the vid now. :p
Usually, yep, especially when they are rectifier diodes for power rails etc., as there will likely be some large-ish caps in the same part of the circuit. You can also end up getting strange readings because the diode / transistor junctions in other parts of the circuit, or even inside chips can be activated by the meter too, which is why you occasionally might need to lift one of the legs to test stuff.
Most of the time, the larger diodes will be for things like DC rectification though, so a quicker / easier "test" is just to measure the power rails that they are supplying. :p
Just confirmed that those diodes are just for rectification from 25V AC into the positive and negative 33-Volt DC rails... (you would actually measure around 48 Volts AC if you put the meter across fuse F100 and F101, but it's a centre-tapped transformer, so you get ~25V per side. ;) ) imgur.com/a/N8890 You can see that directly after the bridge rectifier (four diodes), there are two 4700uF caps (C100 and C101) to smooth the DC output. Sorry for critiquing your ESD precautions the other week btw. :p I really do love the channel, and I watched all the Grinkers ones this week, and the road trip ones are always fun. I was serious about the FPGA too - I'd really like to know which of the older / slightly simpler arcade boards you'd like to see made into an FPGA version at some point. I've just started writing my own CPU core for the SNES audio chip, but would like to tackle a more complex arcade board after that.
I completely agree. ;) It's the only real chance we have of truly preserving the original logic. Software emulators are great up to a point, but not really aiming to do low-level emulation / re-implementation of the logic in most cases. I'm looking to convert something similar to Pole Position in complexity, but I'm not as familiar with the different boards as guys like John and Adam etc. Ideally, I'm after a board that is sought after, or one where the original board is prone to failures etc.
John, the thing about the diode test is actually quite simple. The part of the circuit you are testing is a bridge rectifier (4 diodes) and a (2 in this case i guess) capacitor. When you are testing your diode that capcitor is getting discharged so you see the voltage (0,5 forwarding) is running from 0 to 0,5 volts. When you test the diode in reverse you're charging that capacitor. So, never mind that expensive egr meter, just use some common sense and understand that you must wait a while for your measurement to settle. A transistor is more than two diodes tied together. When measuring with a multimeter you can look at a transistorthat way however.
funnily enough, I was thinking the other day that you really need some kind of test rig for this stuff, like a Supergun. Of course that's really for Jamma and you have so many non-Jamma cabs.
I suspect the reason why you were getting strange readings on the diodes and especially when your meter was beeping for short while is because you was charging a capacitor!
Tempest is one of the great vector games and one of the greatest arcade games of all time, but I'm pretty sure Asteroids was more successful and was the original Atari's biggest hit of all time.
I found a phoenix cocktail cab one time! I was buying a ms pac cocktail for 650 and the guy offered to sell it to me for $300 sadly I couldn't take him up on it. A cocktail table could replace a kitchen table though LOL
Ahahh, it's HERE! This is a pre-watch comment to tell you that I can't wait to see how you finally fixed this bastard! Or... DID you? Starting video in 3... 2... 1... PLAYYYY!
John with all the damage this monitor suffered I have to wonder if you had some sort of surge...is the tempest the first device on that 20A circuit in the basement? If it is then (if) that circuit was surged then it may explain a few things. Might open up your switch panel on the stairs and look for charring inside. As always the vids are great and this community is far better for you being a part of it,
so glad you fixed it man and I hope that Tapper is just a re seat or something simple so you can crack on in the garage. Is it still misbehaving? Unlisted video update on the Tapper? ;)
The only way to test diodes in circuit need an ESR meter, multimeter dont work. Best to remove them. The rest of the board messes up the reading when it get activated even with no power
8:28 laughed my balls off when you changed the test leads in your hands and also changed the possition and thought it was out of range both directions. Something I could do aswell
Also, I also never want to take off the diodes to check them but often just can not say anything without taking one lead off. Better just don't bother. I believe most of your problems is coming from the capacitors why is hard to measure them. I believe thats why the go up and down when switching the leads.
Hi John. I just noticed that on the 6100 monitor for tempest, there is a black spot that shows up once in awhile in the middle of the monitor. This spot appears depending on how you are looking at the monitor. I though that there was a problem with my ipad where I watch the videos but the spot appeared on my desktop computer as well. Do you notice it at all (burn in?).
25 bucks for a new lv2000 upgrade just replace it for sure... this was one of my favorite games.. and the only accurate way to test diodes is to remove them...
I have tested diodes lots of times in circuit when I have serviced televisions and the likely problem you may get momentarily is the smoothing capacitor may try to charge up and give you strange readings
Your wife must be so forgiving John. I know this sounds trivial but you should get yourself an old mirror. Many TV repair men back in the day used a mirror so that they could see the screen whilst they are adjusing the picture.
"Never gonna turn the arcade on ever again until we fix the Tempest..." Haha, what a LIE, LOL, John! Cheaterrrrrr! :-O That should count for _all_ your videos; not just the ones in this series! OHHH! Ahh, cool, you're talking to a guy out here in Utah! Hey, will ya meet me if you ever come out here?
Awesome John, congrats on getting Tempest up & going. I love Phoenix, it's one of my favorites in my collection, as I played it a lot back in the day. By the way this is Greg, the guy you met at Cax last July as I was rolling in my Phoenix cab.:)
Thank you for the input regarding painting the back of the glass bezel!
you're really cranking out the episodes this week. good job
Nice John! I love the Old Skull sticker, I have not heard them in forever!
Glad to see it working! Hope my electrohome g-07 is working soon waiting on my johns arcade branded parts. thanks for all you do!
John thanks for the great video. Glad my cable helped fix your Tempest.
Bought one of those extension cables from Bob Roberts years ago. It changed my life forever...
+Wasting My Potential for sure!
Always played Phoenix in my local cafe on the way to school they also had Moon Cresta which is another great game
Great job on fixing Tempest! I'm so happy for you John! :D
Glad you got tempest back up and working again, jeez man what a hassle that was lol
john you deserve 100's of thousands more subscriber's
+Owen Crawford thanks! :) Tell your friends. ;)
And if you hate it, tell your enemies. (Credit to David Lee Roth.)
I'm watching your *John's Arcade Tour Dec 2015* video and at minute 11 you talk about having voltage problems with the tempest ^_^
Hi, John. ;)
15:40 (ish) - When you're testing diodes in-circuit, you will very often get that "counting up" of the value on the meter, especially in the diode test mode.
This is usually due to capacitance in the same part of the circuit.
Also, the "OL" on the meter actually means "OverLimit", or basically the reading has gone out-of-range for the meter.
(apparently, it's called "Open-Loop" in other modes, which is news to me. lol)
It's important to remember that the reading in Diode mode actually shows the forward-voltage drop across the diode, and not the resistance.
The diode mode is needed because the meter then puts a slightly higher current through the diode (although still very low current of tens of milliamps usually). The meter also puts a higher enough voltage across the diode to activate the junction itself, so the voltage should pass when the red meter probe is on the anode (the side of the diode without the stripe).
(again that voltage is quite low though, only a couple of volts on most meters. It just has to be enough to overcome the usual 0.5-0.7 forward-voltage of the average diode.)
It looks like those two big diodes are fine tbh.
Another thing which causes the weird reasons is because the current from the meter, although low, can charge up the capacitors and other devices on the board, so when you go to swap the probes over, it will often show that weird stuff again.
The only real way to properly test most stuff is to remove it from the board, or to lift one of the legs if it's only a two-pin device.
Testing them in-circuit like this is usually OK for things like big rectifier diodes etc. though.
Watching the rest of the vid now. :p
Oh, interesting! So it's charging the caps on the same circuit and that's why we are seeing the voltage like that on both sides. Huh. Makes sense.
Usually, yep, especially when they are rectifier diodes for power rails etc., as there will likely be some large-ish caps in the same part of the circuit.
You can also end up getting strange readings because the diode / transistor junctions in other parts of the circuit, or even inside chips can be activated by the meter too, which is why you occasionally might need to lift one of the legs to test stuff.
Most of the time, the larger diodes will be for things like DC rectification though, so a quicker / easier "test" is just to measure the power rails that they are supplying. :p
Just confirmed that those diodes are just for rectification from 25V AC into the positive and negative 33-Volt DC rails...
(you would actually measure around 48 Volts AC if you put the meter across fuse F100 and F101, but it's a centre-tapped transformer, so you get ~25V per side. ;) )
imgur.com/a/N8890
You can see that directly after the bridge rectifier (four diodes), there are two 4700uF caps (C100 and C101) to smooth the DC output.
Sorry for critiquing your ESD precautions the other week btw. :p
I really do love the channel, and I watched all the Grinkers ones this week, and the road trip ones are always fun.
I was serious about the FPGA too - I'd really like to know which of the older / slightly simpler arcade boards you'd like to see made into an FPGA version at some point. I've just started writing my own CPU core for the SNES audio chip, but would like to tackle a more complex arcade board after that.
I completely agree. ;)
It's the only real chance we have of truly preserving the original logic. Software emulators are great up to a point, but not really aiming to do low-level emulation / re-implementation of the logic in most cases.
I'm looking to convert something similar to Pole Position in complexity, but I'm not as familiar with the different boards as guys like John and Adam etc.
Ideally, I'm after a board that is sought after, or one where the original board is prone to failures etc.
John, the thing about the diode test is actually quite simple. The part of the circuit you are testing is a bridge rectifier (4 diodes) and a (2 in this case i guess) capacitor. When you are testing your diode that capcitor is getting discharged so you see the voltage (0,5 forwarding) is running from 0 to 0,5 volts. When you test the diode in reverse you're charging that capacitor.
So, never mind that expensive egr meter, just use some common sense and understand that you must wait a while for your measurement to settle.
A transistor is more than two diodes tied together. When measuring with a multimeter you can look at a transistorthat way however.
+Harold Denkers thanks Harold. Makes complete sense.
funnily enough, I was thinking the other day that you really need some kind of test rig for this stuff, like a Supergun.
Of course that's really for Jamma and you have so many non-Jamma cabs.
YAYY, you fixed it! Oh, where's your celebratory CHRISTMAS PARTY music with stars, though?
John get yourself some phobya thermal compound glue for that heatsink. It takes 8-10 hours to dry but once it does it'll never come off again.
So glad you fixed it Johnny!
I suspect the reason why you were getting strange readings on the diodes and especially when your meter was beeping for short while is because you was charging a capacitor!
Congrats John..You are Thee man
I finally understand Zookeeper now.
Yes and i want to see the MK machine working!
Nice Job John. Looks good.
Tempest is one of the great vector games and one of the greatest arcade games of all time, but I'm pretty sure Asteroids was more successful and was the original Atari's biggest hit of all time.
I love Johnny (diving buddy)!
tempest and that zoo keeper look fun to play
I found a phoenix cocktail cab one time! I was buying a ms pac cocktail for 650 and the guy offered to sell it to me for $300 sadly I couldn't take him up on it. A cocktail table could replace a kitchen table though LOL
good good good, I have a tempest coming in a few weeks and may need the info
Awesome, Glad it works again!
Ahahh, it's HERE! This is a pre-watch comment to tell you that I can't wait to see how you finally fixed this bastard! Or... DID you?
Starting video in 3... 2... 1...
PLAYYYY!
John with all the damage this monitor suffered I have to wonder if you had some sort of surge...is the tempest the first device on that 20A circuit in the basement? If it is then (if) that circuit was surged then it may explain a few things. Might open up your switch panel on the stairs and look for charring inside. As always the vids are great and this community is far better for you being a part of it,
Good morning, John!
so glad you fixed it man and I hope that Tapper is just a re seat or something simple so you can crack on in the garage. Is it still misbehaving? Unlisted video update on the Tapper? ;)
The only way to test diodes in circuit need an ESR meter, multimeter dont work. Best to remove them. The rest of the board messes up the reading when it get activated even with no power
8:28 laughed my balls off when you changed the test leads in your hands and also changed the possition and thought it was out of range both directions. Something I could do aswell
Also, I also never want to take off the diodes to check them but often just can not say anything without taking one lead off. Better just don't bother. I believe most of your problems is coming from the capacitors why is hard to measure them. I believe thats why the go up and down when switching the leads.
LOL I was wondering what was going on there. I didn't notice that! XD
Best to test diodes out of circuit most of the time, if not all the time to get a accurate reading.
That's my experiences anyway.
John - just attach the heatsink with a few dots of superglue
25:55 probably just held on by the thermal paste. Should be easy enough to fix and not urgently needed in the short term.
hey John how do you connect the jamma harness to a midway coin door am having a lot of trouble with that can u help plz
The bull starts here 🐂
LOL. You're charging and discharging the capacitors with your Meter!
Hi John. I just noticed that on the 6100 monitor for tempest, there is a black spot that shows up once in awhile in the middle of the monitor. This spot appears depending on how you are looking at the monitor. I though that there was a problem with my ipad where I watch the videos but the spot appeared on my desktop computer as well. Do you notice it at all (burn in?).
+Edward Letendre yeah. It's burn
25 bucks for a new lv2000 upgrade just replace it for sure... this was one of my favorite games.. and the only accurate way to test diodes is to remove them...
tapper is powered by a galaxy note 7 lol
Do I need to come back to update your Firefox? :)
Ahh, yeah, show us fixing your mic problem, ha? Please.
Yeah, let's be a zookeeper and ''jump'' some animals!!
You can't test diodes in circuit. The rest of the circuit influences the reading.
+Konjono Awesome I believe normally that's true. But you can with these to get an idea what's happening.
I have tested diodes lots of times in circuit when I have serviced televisions and the likely problem you may get momentarily is the smoothing capacitor may try to charge up and give you strange readings
Still waiting for my viewer mail :(
Your wife must be so forgiving John. I know this sounds trivial but you should get yourself an old mirror. Many TV repair men back in the day used a mirror so that they could see the screen whilst they are adjusing the picture.
+craig gilchrist I have a mirror. :)
Pitty we as viewers cant shout back at you, left a bit, right a bit. Lol
I thought it was to check for wife with a knife behind ones back. ;)
dual purpose mate
👍🏻
"Never gonna turn the arcade on ever again until we fix the Tempest..."
Haha, what a LIE, LOL, John! Cheaterrrrrr! :-O
That should count for _all_ your videos; not just the ones in this series! OHHH!
Ahh, cool, you're talking to a guy out here in Utah! Hey, will ya meet me if you ever come out here?
YOU NEED AN E. S. R. METER to test in circuit
+Joseph M I have one. But diodes?
john its me again please clean your popcorn maker it can get moldy thanks
Wolves United lol
lol comments can become 100's of nagging wives one after another in line
10
The coked out gasping for breath, figgeting and nose rubbing is destroying a really great channel.
+Jjjj H I was sick. Calm down.
I didn't notice any of that really. Maybe you're having your period?