Power Question

ResTech

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Hope this isn't too much of a newb question. I've been Googling and watching YouTube videos and nothing is coming up.

Picked up a Midway Cocktail Donkey Kong Jr.

It works occasionally, for a bit. Consistently powers on and about 50% of the time it is playable for a stretch of time.

When I bought it I was lead to believe it was either the power switch or the board that was the issue with it.

Went to check the voltage on the power supply and had some dubious numbers; 5 volts was reading at .2, +12 was coming in at 5 and -5 was coming in at .2.

Used two different multimeters and I'm fairly certain I'm using the right setting on them, although one is automatic.

Figured it must be the power switch so I changed it.

Same results are happening. Checked the power coming in and that's at 113, so it isn't an issue of the wall to the switch.

Fully prepared for the "you're an idiot and this is how to use a multimeter" moment, although it isn't as though I haven't spent a ton of time looking into how to check correctly.
 
i would post some pictures of your setup because midway doesn't make the donkey kong jr because its made by nintendo. the pictures will help see what exact boards/power supply you have so we can help.
 
Make sure your multi-meter is set to DC voltage lowest setting and you are connected at the correct test points. The game wouldn't boot at all with that low of voltage so something in the way you tested must not be exactly right. Pics would help for sure.
 
as u are a newb , i would post picurces of multimeter setup also
.2 tells me u are in ac range and not dc
but u know
just post the setup of your meter-'s

ed
 
Hey all....thanks for taking the time to read and respond. I really appreciate your help with this. And while I have used a multimeter in the past (I used to modify guitar amps and wire up electric guitars) I will admit that this is something very different than what I was doing before, so thanks for being patient and helping me out.

I added a picture of the multimeters I am using. The smaller one I have had for awhile and was concerned about accuracy since I was getting those odd readings so I picked up the second one, which was giving me the same reading. Both are set to the setting I was using to take readings.

I took readings by using the FG setting on the switch with the black probe and then using the red one for the other (+5 or -5 or +12). I placed the probe directly on top of the screw used to secure them to the terminal.
 

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as u are a newb , i would post picurces of multimeter setup also
.2 tells me u are in ac range and not dc
but u know
just post the setup of your meter-'s

ed

AC range is fine, checked it and it came in at 113. I verify this pretty regularly at various places around my house with guitar amps.
 
I have that same Klein meter. To get DC readings, you have to press the round "SEL" button. Right now it is set to read AC.

FG is your AC GND. Use GND for your DC GND and you should be fine.
 
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hi
u do understand u are working with >dc< voltages right ?
so set your meter to auto dc and re mearsure

ed
 
I have that same Klein meter. To get DC readings, you have to press the round "SEL" button. Right now it is set to read AC.

FG is your AC GND. Use GND for your DC GND and you should be fine.

Well, that certainly makes a big difference!

So with some adjustments:
+12 is 12.43
-5 is -4.72
+5 is 5.11

Well, nice to see it getting some numbers that make sense.

Of course the machine is still doing this....

Anyone got any ideas?

And thank you all for the help. I appreciate it greatly.
 

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Have you re-seated all of the chips on the board? For instance, push down on them. Also, take off the edge connector and inspect it for corrosion. You should also check the voltages at the edge connector to see if there is any drop-off.
 
u have a knob on the power supply
turn it down well mertering the +5v line
and bring that down to about 5v on the mark
then power cycle game (off/on) give about 10-30 sec's between cycle
and see if the board fully boots

ed
 
Have you re-seated all of the chips on the board? For instance, push down on them. Also, take off the edge connector and inspect it for corrosion. You should also check the voltages at the edge connector to see if there is any drop-off.

Tomorrow I will check the chips on the board. I just got done removing it from being mounted underneath the CRT and mounting it along the side wall of the machine.

So, if the board has problems is it something that people fix or is it a better option to try and find a replacement?

Also any guides to checking voltages at the edge connectors?

Thanks for all the help.
 
ya ppl fix them all the time
but u are jumping the gun here
dial in your power supply first
i explained how in my last post to u

ed
 
+12 is 12.43
-5 is -4.72
+5 is 5.11

12.43 is unregulated, so it's ok
+5 is a tad bit high for my liking but that's not your problem I don't think
you want that at +5vdc ON THE BOARD and then check it on the output of the power supply just to see how much voltage drop youre getting across the connectors etc

*remember* logic ground and field ground (earth ground) are different things
you can get screwy readings when using earth ground when you're trying to measure the logic voltage good luck
 
ya ppl fix them all the time
but u are jumping the gun here
dial in your power supply first
i explained how in my last post to u

ed

I dialed it down and got it as close as 5.04. Turned it on and got the same screen, only now it's mostly green. Rebooted a few times and it's the same.
 
http://www.arcade-museum.com/manuals-videogames/D/DKJr.pdf

Page 10 of this manual will show you the edge connector.

Cool...I'm going to stash that away.

So, I think I'm going to gut this and turn it into a MAME.

Now, hang on...before you get out the torches and pitchforks.

I don't really have a huge amount of space in my home to tinker with something like this. Currently it's taking over a porch which with the change of seasons is about to become some very premium space.

I do, however have a smallish workspace where I can turn one of the shelves into a nice setup to troubleshoot and repair the components without a cabinet to take up space.

I am getting some heat from the Missus for said porch takeover and if I'm ever going to advance on to Project Number 2 and beyond I need this to be a victory pretty quickly.

So, with that in mind, a temporary gutting and backfilling with a MAME is in order while I get the old components working the way they should be and maybe even look for an empty cabinet or build one.

Thanks for all the help. I'm certain as I get past the short-term victory and move into the long-term plan I'll be on here making a nuisance of myself and trying to return the favor you all have been so generous with for helping me out this far.
 
https://www.mikesarcade.com/cgi-bin/store.pl?sku=JAM2NIN

If you are going to do something like that, use one of these so that you do not have to mess with any of the wiring harness.

That's actually REALLY cool! As I'm walking through the steps in my head I never anticipated that something like that might be out there. That, literally, saves me a step or two as I plan it all out.

Thank you!
 
in the land of people that think running their games at 5.5V is ok, now suddenly think 5.11 is too high?

somewhere along the way in my travels I amassed the knowledge that most logic components have an operating tolerance of 4.75-5.25V. go below 4.75 and risk malfunction, which will trigger the watchdog on the board if it has one and cause it to reset. if no watchdog, expect the game to lock up. go above 5.25 and you run the risk of burning out chips.

I don't think 5.11 is too high. it's in my experience that Japanese games can be run on the lower end, if that's what everyone's getting at here. it's not going to self destruct at 5.11 however. for the record, I run voltages extremely conservative, at about 5.05 for a majority of games, unless the game is unreliable at that setting and resets. (Mortal Kombat T-unit games and Y-unit Terminator 2 seem to be the usual suspects there) 5.15 at the chips is the highest I will go. you have to account for drift from the adjustment pot, it can go up or down on its own if you move the game or bang it around a lot, or potentially the natural dirt accumulation there. it's a standard practice of mine to wipe the adjustment pot; you need a reference point when you're done however, you will have to quickly test +5 with the game disconnected permitting you have a junk power supply; some of those don't like running without loads.

if you wish to know more about how this works you can read the PSU guide in my signature.
 
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