OP
OP
The +12 is about 12.85v... but I dropped a 2nd switcher in and got it down to 12.6v or so with very little change (if any). What is a 7812?
Spy Hunter Behavior
- Thread starter FrizzleFried
- Start date
The +12 is about 12.85v... but I dropped a 2nd switcher in and got it down to 12.6v or so with very little change (if any). What is a 7812?
OK, that makes sense. You don't get turbo until about 1E and full turbo until around 20h (in the user input screen). 1A is going to get you sucky speed.
You can either replace the pot and get back to around 0-22h or you can also try adjusting the current pot to tweak the high end range. By doing that you will lose the low end range though so the car will always creep forward even with your foot off the gas pedal.
There are times when you don't want to move forward or want to do so very slowly (trying to navigate carefully around a wreck right in front of you, or there are spiked wheel guys right in front of you) for example.
You can slightly relax the screws holding the pot in and twist the the pot to adjust the high end range and it's definitely a hack but you may not have to replace your pot that way and you can see results in a couple of minutes.
Just throwing the option out there.
You can either replace the pot and get back to around 0-22h or you can also try adjusting the current pot to tweak the high end range. By doing that you will lose the low end range though so the car will always creep forward even with your foot off the gas pedal.
There are times when you don't want to move forward or want to do so very slowly (trying to navigate carefully around a wreck right in front of you, or there are spiked wheel guys right in front of you) for example.
You can slightly relax the screws holding the pot in and twist the the pot to adjust the high end range and it's definitely a hack but you may not have to replace your pot that way and you can see results in a couple of minutes.
Just throwing the option out there.
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OP
OP
Here's a bit of a "game changer" as far as what i thought the issue was...
Well...even with the lamp driver board disconnected... I went to replace the lamp in the coin door. Guess what... as soon as I installed it, it lit up... along with the same "POP" and "background noise" experienced when the 12v lamps the lamp driver runs turns on and off...
...so it's surely NOT the lamp driver board.
Damnit.
Well, I have a Spy Hunter power supply on it's way... I hope that rectifies the issues... if not, I guess I am down the either the amp or the sound board, right?
Well...even with the lamp driver board disconnected... I went to replace the lamp in the coin door. Guess what... as soon as I installed it, it lit up... along with the same "POP" and "background noise" experienced when the 12v lamps the lamp driver runs turns on and off...
...so it's surely NOT the lamp driver board.
Damnit.
Well, I have a Spy Hunter power supply on it's way... I hope that rectifies the issues... if not, I guess I am down the either the amp or the sound board, right?
Dual amp boards are like $15 if it comes to that. Have you run the diags on the game sounds and made sure everything is ok?
If you lived locally I could come by with a complete set of spare boards (minus the main boards) to swap in and we could have it nailed in about 20 minutes.
OP
OP
Yup... all sounds play as normal. My guess is it's going to be the PS... I mean what else can it be? The only thing common between the sound circuit and the lamps are... the 12v line.
a 7812 is a 12v positive voltage regulator. It regulates the +12 to exactly +12v. I'll get to it here in a second....
Ok, so, did you recap the amp board, and reflow the solder on it? especially the headers and the amps themselves - those can make it hum, and badly.
The reasoning on the 7812 is this (and it helps to see what the 12v DC looks like coming off of a switcher). The switcher takes an AC waveform (which is a sine wave), then using capacitors and switching transistors clips it into what should be a true DC voltage, with no wiggles whatsoever. However, if you look at it on a scope, you'd most likely see some voltage variation, not much, but enough for the amp to see that voltage fluctuation as a hum. If you looked at the waveform on an O'scope, the AC on top of the DC would be fairly small - like probably less than 1/4 volt, depending on the quality of the switcher, much less. So, if your +12v is running 12.6v, but has ac on it so that its actually varying between 12.35, and 12.85 (or thereabouts, it really depends on how your voltmeter handles dc measurements). The 7812 clips off the voltage at exactly 12v, and gives a nice smooth DC voltage, and gets rid of the AC ripple (in theory at least - i'm not an EE, but i know its helped someone in the past, and thats my theory of why).
Anyway, the noise supressor that i posted the link to does basicly the same thing, but in a different way. It allows the ac ripple to be passed off to ground or filled in with stored energy.
Rat shack most likely will have a 7812 in stock. Here's a link -
http://www.radioshack.com/product/index.jsp?productId=2062600
Anyway, hooking it up is simple - there's 3 leads. Solder wires to each. Ground (ties to logic gnd on the switcher), your 12vish input (+12 on the switcher) , and your 12v exact out (ties to the +12v lead you removed from the switcher).
Edit - there's really no need to replace the amp board. If you have all the sounds, its not bad, but most likely just needs recapping, and chances are, even if you buy one, you may need to recap it as well.
Further - remember that even if you have a good power supply board, you may have to replace the big caps in the suitcase (as well as the bridge rectifier) before you get a working original power supply - and those 55k and 100k caps aren't cheap.
Ok, so, did you recap the amp board, and reflow the solder on it? especially the headers and the amps themselves - those can make it hum, and badly.
The reasoning on the 7812 is this (and it helps to see what the 12v DC looks like coming off of a switcher). The switcher takes an AC waveform (which is a sine wave), then using capacitors and switching transistors clips it into what should be a true DC voltage, with no wiggles whatsoever. However, if you look at it on a scope, you'd most likely see some voltage variation, not much, but enough for the amp to see that voltage fluctuation as a hum. If you looked at the waveform on an O'scope, the AC on top of the DC would be fairly small - like probably less than 1/4 volt, depending on the quality of the switcher, much less. So, if your +12v is running 12.6v, but has ac on it so that its actually varying between 12.35, and 12.85 (or thereabouts, it really depends on how your voltmeter handles dc measurements). The 7812 clips off the voltage at exactly 12v, and gives a nice smooth DC voltage, and gets rid of the AC ripple (in theory at least - i'm not an EE, but i know its helped someone in the past, and thats my theory of why).
Anyway, the noise supressor that i posted the link to does basicly the same thing, but in a different way. It allows the ac ripple to be passed off to ground or filled in with stored energy.
Rat shack most likely will have a 7812 in stock. Here's a link -
http://www.radioshack.com/product/index.jsp?productId=2062600
Anyway, hooking it up is simple - there's 3 leads. Solder wires to each. Ground (ties to logic gnd on the switcher), your 12vish input (+12 on the switcher) , and your 12v exact out (ties to the +12v lead you removed from the switcher).
Edit - there's really no need to replace the amp board. If you have all the sounds, its not bad, but most likely just needs recapping, and chances are, even if you buy one, you may need to recap it as well.
Further - remember that even if you have a good power supply board, you may have to replace the big caps in the suitcase (as well as the bridge rectifier) before you get a working original power supply - and those 55k and 100k caps aren't cheap.
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OP
OP
The strange thing is the hum isnt bad...when no 12v lamps are lit... as soon as a SINGLE 12v lamp is lit (be it the coin door lamp, or any of the 12v lamps driven by the driver board) the hum begins and the pop at power up and a pop at power down (of the lamp).
If there was a constant hum all the time, I'd say you're likely on the right track, but why only when even a SINGLE 12v lamp is lit?
I'll recap and re-flow the amp board though just in case...
... and now you have me worried about the filter caps on the bottom of the cab with the linear PS coming...
EDIT: BTW - My docs file does not include the schematics/info for the amp board... anyone have it?
If there was a constant hum all the time, I'd say you're likely on the right track, but why only when even a SINGLE 12v lamp is lit?
I'll recap and re-flow the amp board though just in case...
... and now you have me worried about the filter caps on the bottom of the cab with the linear PS coming...
EDIT: BTW - My docs file does not include the schematics/info for the amp board... anyone have it?
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OP
OP
OK... re-capped the amp board... reflowed the connectors... reflowed the amp chips... no change...
...and just for shits & giggles I disconnected the sound board and fired her up. Sure enough... when I plug the 12v bulb in to the coin door... "POP" and the background "static" more than doubles so I can eliminate the sound board as the culprit which leaves me back with the power supply/adapter... right?
tec9
Active member
My Spy Hunter did the same thing, and also had a background hiss. It was the linear power supply. I swapped another power supply PCB from my stash and the sound was drastically better. When I put the power supply that was originally in Spy Hunter in one of my other MCR games, it worked fine. I think Spy Hunter is the most power hungry machine in the MCR series, so if your power supply isn't 100% you will have issues.
-Mark
-Mark
vicjw66
New member
Well this is tough. The lamps are lit by the 12v coming from pin9 connector 5 at the power supply. It is an orange wire that goes into pin1 J2 connector on Lamp driver board. Goes through R19 then out of pin 5 and 6 to light the lamps and completes the circuit through J1 pin3 for guns,pin5 smoke,pin6 van,pin8 missile,pin7 oil. I see many points of ground. With a switcher I could see a lack of ground at one of these points as possible problem. I would definitley test for 12v at pin 14 of both U2 and U3 2068's. pin 13 is ground. Also the 4700mf c8 is a big suspect. Test from 3rd prong of cord plug to ground points on lamp driver for continuity and low resistance.
Robotron Jon
Well-known member
part it out
part it out
part it out
Oh, you're just ticked because his monitor synced for him right away!
Jon's close to getting his game to 100%... as long as he doesn't have to do anything with his power brick, once he puts in the new linear power board and accelerator pot he'll be sitting pretty.
It'll be pretty interesting to see if the linear power board fixes this noise issue too.
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OP
OP
I sure hope I don't have to cough up the $35-$40 for the filter caps... it's one thing to replace a big blue and it not fix the issue... it's a whole other thing to replace those two bad boys and have it fix nothing.
the 7812 is worth a shot.... only about $3 at rat shack. simple as all hell to hook up. has 3 legs, 12v in, 12v out, and ground. run the ground to the switcher, put it inline with the 12v coming off the switcher before it plugs into anything else. bingo.
sounds good, except he gets the hum regardless of whether the lamp driver board is even plugged in or not.
I really think it boils down to the 12v supply not being anywhere near as precise on switchers as it needs to be. Look at the 12v supply from a switcher sometime with a load on it on an oscope sometime and you'll see what i mean.
Imho, it boils down to there not being enough capacitance to fill in the +12v wiggles when there's a load on it. That's why it hums once he hooks up anything to the +12. The 7812 takes advantage of the +12 being way over +12, and clips off the ripple (at least that's my theory)....
My tron has Spaeth's atx adapter, and it has a very soft him, its not loud enough to bother me, so i've not worried about it. If it did though i'd add either the 7812 or a noise suppressor similar to what i posted a link to above. If it wasn't such a huge pain, i'd swap it into my SH and play with it, but really, i have neither the time nor the inclination.
OP
OP
Screw it... I'll try the 7812 tomorrow... why not. If it works, I'll sell the Spy Hunter PS or just keep it as a back up. The 7812 looks like it needs to be hooked up to a heat sync... no?
vicjw66
New member
I sure hope I don't have to cough up the $35-$40 for the filter caps... it's one thing to replace a big blue and it not fix the issue... it's a whole other thing to replace those two bad boys and have it fix nothing.
Option #1 You stick with switcher.
Caps are not needed or used and in no way affect your game. Replacing them will absolutely have no affect.
Option#2 You go with original.
Almost 100% certainty that those filter caps need replacing.
Either way spyhunter needs good grounding including 3 prong plug.
vicjw66
New member
I would logically think so unless you want it to fail quickly.
vicjw66
New member
> Almost 100% certainty that those filter caps need replacing.
FWIW, mine didn't. I mean, they may have needed replacing but there were no real symptoms that would cause me to replace them.
I DID end up replacing them anyway but that's only because long term they'd need to be replaced at some point and I had a repair guy onsite who I was paying a flat labor charge to for other stuff...
