Zac Time Machine has died

[63wizz]

You would think with a time machine you could go back in time before it died and prevent it

Any how i was playing it yesterday and the ball jumped up behind the mini playfield and got stuck, the mini PF was raised and the ball shouldn't enter the area where the targets are in this up position,
So instead of taking the glass off i thought i would Tilt the machine and hope when it started back up the mini PF would go down and release the ball.
All the scores flashed on and off all zeros, and the game never started up again.
I turned the game off and back on, to be honest i dont know what has happened.
Now the game plays garbage sounds, the scores are all zeros with the last digit flashing, press credit button and it does not register any thing, same as the start button.
Im sure the CPU is booting the LED stays on.
the Sound board unplugged plays sound and speech when the test button is pressed.
The test advance button does not work.

I have tried.
Re seating socketed chips.
Replaced ic38 3081 chip.
Tr3 BC548 transistor.
Replaced R34, D3, C5 as suggested for board resetting.

Im stuffed any help would be appreciated.
Seems it stuffed up after Tilt im working on switch row and columns

Ian

[Retropin]

Whats up where the ball got stuck?

If there are switch and lamp connections then you may have shorted between the two with the metal ball... im guessing here of course.

Is the mini PF still raised?

Make sure your tilt switch isnt stuck on.

If the CPU led is on.. then the program is running... but this is really just a small part of the CPU board.

I would be disconnecting all boards and boot the CPU.
Then add the driver
Each time you advance one step turn game off and back on... so turn game off to add driver

Then add connectors one by one each time turning off the machine... you should be able to have all connectors off the driver and only connect CN17 at the bottom... this is ground path to all solenoids etc... with this connected you should be able to manually lift PF and lower by shorting tabs of transistors to ground.
Idea im thinking is to get the game to "normal" position and go from there.

If all is good with CN17 in place .. try adding the display connector... then the switch connectors... then lamps etc.

Do displays display normal with Driver off etc.
If ball got stuck where switch diodes are then test these etc

If we do one thing at a time, then we should be able to narrow the fault down to a particular area

[63wizz]

The ball was in the normal play area when the mini PF is down, there is nothing the ball can hurt in this area.
I will try some of your suggestions and get back to you.

ian

[63wizz]

I would be disconnecting all boards and boot the CPU

CPU boots LED on, with only CN9 plugged in.
CPU did not boot next time.
Checked test points on power supply and TP7 is up and down, this is the power failure detect circuit, im not sure what  volts its supposed to be.

Ian

[63wizz]

The CPU boots some times, ive done some Readings on the Power board, and this is what ive found.

TP1 165v with cpu booting and not booting, should be 170v

TP2 13v with cpu booting and not booting, should be 12v

TP3 5.8v with cpu booting and not booting, should be 5.6v

TP4 5.9v with cpu booting and not booting, should be 5v

TP5 68v with cpu booting and not booting, should be 39v

TP6 -5.2 with cpu booting and not booting, should be -5v

TP7 5.0 when cpu has booted, fluctuates between 2.7v to 5v

Ian


Add Text:

I have taken the Mpu board out and connected it to a computer power supply, the board will only boot some times 

[ajlaird]

They all look within spec apart from TP5, and maybe TP7.

I would definitely be checking why you are only getting 39V at TP5.

[Retropin]

The CPU booting only sometimes might not be something to get too concerned about... the POWER FAILURE cct has a timer attached to it and needs the 5V on pin 8 CN11 to be on then removed then on again.... you are tricking the CPU to boot by doing this and sometimes it doesnt work... also sometimes it will boot without the pin8 removal..

The power board is what concerns us most right now... you should have around 43VAC coming in from the transformer.. test this across pins 7 and 8 CN1 ( pin 7 feeds fuse F5)... you should then have 39VDC at pin4 CN2, 5&6 CN3, TP5 and 3&4 CN4... if you dont have approx 39VDC then the bridge P5 is gone and needs replacing.. also replace R21 ( 680 Ohm 10W) at the same time.

While you have the board off replace the caps C6 & C6 ( 10,000uf 20Vea).. also C7 ( 0.33uf) D4 ( 1N4003) R12 ( 100 Ohm) and lastly C8 ( 0.1uf)... this is your smoothing cct and also feedback cct to 5V regulator... this will clean up the 5V and smooth any ripple out.

Now if we are lucky ( which we are invariably not with Zac games) the CPU should boot OK in the machine... if not and TP7 is still fluctuating ( this is cap C5 charging and discharging) then we have a fault with this cct either on CPU OR power board

[63wizz]

The power board is what concerns us most right now... you should have around 43VAC coming in from the transformer.. test this across pins 7 and 8 CN1 ( pin 7 feeds fuse F5)...

CN1 pin 7 & 8 50v with no load, fuse F5 49v.


you should then have 39VDC at pin4 CN2

CN2 pin 4 = 67v

5&6 CN3

67v

TP5 and 3&4 CN4...

67v

if you dont have approx 39VDC then the bridge P5 is gone and needs replacing.. also replace R21 ( 680 Ohm 10W) at the same time

looks like a trip to jaycar, but they dont have the 680 ohm resistor

Thanks for the help Gav

Ian

also SCR1 2N6564 is missing from the Power Board, what can i use instead of this.

[63wizz]

While you have the board off replace the caps C6 & C6 ( 10,000uf 20Vea).. also C7 ( 0.33uf) D4 ( 1N4003) R12 ( 100 Ohm) and lastly C8 ( 0.1uf)... this is your smoothing cct and also feedback cct to 5V regulator... this will clean up the 5V and smooth any ripple out.

I replaced all the above components and all Test Points remained the same as before, with TP5 still 67v.
Then i unplugged this great big capacitor that is screwed to the side of the cabinet. i had not read or seen any thing about it in the schematics, unplugged and turned machine back on and the 67v has come down to 43v.

The game still wont boot though.

The two Brown wires at CN1 pins 3 & 4 are supposed to be 10v AC, I get 0.02 on AC and -5v on DC.

Ian

Will put a pic up of the large CAP soon

[Retropin]

?????????????A cap on the solenoid cct? WTF? 

[Mr Pinbologist]

?????????????A cap on the solenoid cct? WTF? 

+1  Id say someone put that cap there to try to give the solenoids more power 

[63wizz]

?????????????A cap on the solenoid cct? WTF? 

+1  Id say someone put that cap there to try to give the solenoids more power 

well it worked because when the machine was working the ball was pretty lively off the slings and pop bumpers.

any way the machine still wont boot, should i do the acid damaged area to rule this out.
im a bit scared to take out the ram which is socket ed, because i will lose the game settings and with things not working i will be unable to enter the settings again.

Ian

[Retropin]

In all honesty - you have nothing to lose. The RAMs are the first chips that will be affected by any corrosion... the sockets may have saved the actual IC's from being ruined, but they might just be floating due to the traces being eaten away.. so any RAM settings would be lost already.

IF you have corrosion then it needs to be fixed up before it gets worse - mine didnt look too bad, but once the green film was taken off the board to reveal bare traces it was astounding just how far the rot had travelled.
IF the RAMs are eaten away, i have some 6514 here and 2114 are easy to come by... seem to be on every arcade board from 80's era

Am i right in assuming that your board boots sometimes on the bench but not in the game?

[63wizz]

In all honesty - you have nothing to lose. The RAMs are the first chips that will be affected by any corrosion... the sockets may have saved the actual IC's from being ruined, but they might just be floating due to the traces being eaten away.. so any RAM settings would be lost already.

IF you have corrosion then it needs to be fixed up before it gets worse - mine didnt look too bad, but once the green film was taken off the board to reveal bare traces it was astounding just how far the rot had travelled.
IF the RAMs are eaten away, i have some 6514 here and 2114 are easy to come by... seem to be on every arcade board from 80's era

Am i right in assuming that your board boots sometimes on the bench but not in the game?

Yes i have had the board boot on the bench, but have had no luck with it in the machine.
when 5v from the computer supply is connected to the 5v pin at CN9 ( i think ) the power goes through a diode and comes out at 4.33v.
when connected to the machine power supply it gets 5.8v and comes out, i think at 5.6v. and wont boot.
On the bench sometimes the LED would flash on and off for ages and then would stay on for a second or two then start flashing again.

Ian 

[Retropin]

OK.. CPU isnt booting.. its trying hard to though.
The logic voltage on Zacs is a little higher than normal, but all the IC's are well within range and youll find that the voltage drops as it fans out through the board.
The RAMs are right in the corrosion zone.. the pads will be the main issue IF it is corosion that is the problem here.. we havent determined that yet.
The 2 RAms are a bugger of a job... pulling off a socket will do some damage to what could be a delicate area.. this will need to be repaired.
The cct between the 2 RAMs i didnt enjoy rebuilding, but in all honesty it took maybe 2 hrs tops
R1, D1 and D2 cop a flogging with corrosion too.
Theres a large ground path at battery -ve.. mine was eaten away and all R2 - R9 had floating pads... check all this.. buzz it out well, its all one of those jobs that you dont want to have to go back to.

In all honesty, your CPU was booting - now its not, but it is continually trying, not just locked off..
Have you checked all signals on the 2650 CPU?.. This can give very big clues as to why its not booting.
Check that you have signals on data bus on 2650.. anything missing and strongly suspect broken traces or socket fault on Eprom to CPU.
A logic probe is excellent for zac games.. apply to pin 10 IC5 ( 2114 RAM).. make sure its pulsing... then CPU pin 23.. same signal.. should be pulsing.

Id say.. do all this on the bench.. the board seems happier there