Spy Hunter power problem

whammoed

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Spy Hunter starting acting up today. Giving me the garbled screen and resetting. Did what I normally do and plugged in a switcher kit and sure enough it works so I have a power issue. Check 5v on the power board and it is at 5.11 which is a little low for the current boardset in there. It likes 5.25 or maybe a bit more. The adjustment knob on the power board works fine without the boardset plugged in but won't go above 5.11 with the board.

Should I shotgun the power board or is there a specific part or parts that may be to blame?

Weird thing: I notice the base is clipped and raised on Q201. No idea why this was done but it was working for a year.
 
If all the voltages are fine....you could shotgun the reset section of the power supply. There's not a lot to it. Are you sure the problem is the power supply board?

Edward

Voltages are not fine. Can't get past 5.11 with boardsets plugged in.
Works fine with switcher installed so I am pretty sure it's the power board.
 
Shotgunned it. I'll post results later after testing.
 
After the rebuild I am able to get the +5 up to 5.28 which is just enough to get this boardset to boot. So far so good. Going to let it burn in for a while before I declare victory. Reset circuit is now in tact again since that transistor was part of the rebuild kit.
Strange the gas pedal is now out of calibration a bit. I'll have to adjust it back up to get the turbo to kick in again. Just a coincidence I guess?
 
Do you still have the original blue gas pedal pot in the game?

If so, you should replace it. You should be getting values back from it ranging from 0 to 23h. If you're not, replace it!

Regarding coincidence or not, the calibration values for the pots are battery backed up. Once you lose the backup the calibration will be off.
 
Got the pot readjusted. I have brand new pots if it needs replacing.

The bad news. Game will reset sometimes when coin is inserted.
I do not get this behavior when the switcher is installed. If it weren't for the hum I would use it permanently. The switcher is running fine even at 5.00 volts. I thought it needed more but I guess not. The original power board would not boot the game until it was turned all the way up to ~5.28.

Any ideas? I replaced everthing listed here except the connectors and U1/U2.
http://therealbobroberts.net/midway.html
Suppose I'll do that next.
 
I wonder if you've got excessive AC leak from one of the big caps on the transformer assembly.

Edward
 
Welcome to the Spy Hunter club. I thought I got a great deal on mine for $80. About $300 in parts and countless hours labor later it still has issues. Damn you MCR III engineers!!!
 
Still no go. I can get the voltage a little higher this time, but it is still resetting when you drop a coin although a little less often. I can watch the voltage drop a bit sometimes when it happens.
I even tried re-doing the reset circuit hack that was done previously by clipping the base on the transistor. No change.

BTW: I don't recommend replacing the connectors unless you have corrosion. The pins just barely fit in the holes even when all the solder is completely cleared out. It was a royal pain.
 
Sounds like there's a short of some kind, like a solder splash, in your coin switch circuit. Inserting a coin should not cause your 5v supply to drop!
 
Sounds like there's a short of some kind, like a solder splash, in your coin switch circuit. Inserting a coin should not cause your 5v supply to drop!

Works fine when running on switcher. Haven't had the main boards out for this problem. Been concentrating on the power board since everything is fine with the switcher...except for the HUUUUMMMMMMM.
 
If I unplug the coin meter the resetting stops. Something about the pulse to the coin counter causes the issue. I notice on the schems that the coin meter is powered via the +5 unregulated. What's the connection between the +5 regulated and the +5 unregulated? Maybe that will point me in the right direction.
The rebuild must have helped something because I couldn't get this far before.

Who's the MCR expert round here?
 
If I unplug the coin meter the resetting stops. Something about the pulse to the coin counter causes the issue. I notice on the schems that the coin meter is powered via the +5 unregulated. What's the connection between the +5 regulated and the +5 unregulated? Maybe that will point me in the right direction.
The rebuild must have helped something because I couldn't get this far before.

Who's the MCR expert round here?

CDJump

(filler filler)
 
If I unplug the coin meter the resetting stops. Something about the pulse to the coin counter causes the issue. I notice on the schems that the coin meter is powered via the +5 unregulated. What's the connection between the +5 regulated and the +5 unregulated? Maybe that will point me in the right direction.
The rebuild must have helped something because I couldn't get this far before.

Who's the MCR expert round here?


not me, i do repair mcr pcbs though....
My guess is either a bad coin meter, or maybe the diode is shot on it. Without digging through the schems for the power supply, i'm not sure exactly where or how they're related. I'd guess that the +5 unregulated is just powered by the +5 on the switcher adapter, though, which would be able to provide more current than the +5 unregulated that runs the meter in the original game. Why that would cause a reset though, i'm not sure.... I know that there are 2 transistors on the ssio that send the coin meter ground pulse to the meter itself, one of those could possibly be bad, too, but i kinda doubt it.
If it were me, i'd drop another coin counter from a known working game and see if that fixes it, if not, i'd unsolder the 2 transistors on the ssio and see if that fixed it, if that wasnt it, i'd look at the +5 unregulated part of the power supply and see if its tied into the reset circuit at all.
 
not me, i do repair mcr pcbs though....
My guess is either a bad coin meter, or maybe the diode is shot on it. Without digging through the schems for the power supply, i'm not sure exactly where or how they're related. I'd guess that the +5 unregulated is just powered by the +5 on the switcher adapter, though, which would be able to provide more current than the +5 unregulated that runs the meter in the original game. Why that would cause a reset though, i'm not sure.... I know that there are 2 transistors on the ssio that send the coin meter ground pulse to the meter itself, one of those could possibly be bad, too, but i kinda doubt it.
If it were me, i'd drop another coin counter from a known working game and see if that fixes it, if not, i'd unsolder the 2 transistors on the ssio and see if that fixed it, if that wasnt it, i'd look at the +5 unregulated part of the power supply and see if its tied into the reset circuit at all.

will do
the base on q201 is clipped right now...doesn't that take the reset circuit out of the picture?
 
depends on where that transistor gets its power. If it happened to powered from the +5 unregulated, then if that voltage dropped, it would drop the reset voltage as well.
I really think its a bad coin counter.
 
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