E-1236 stuck on Error 6

[MarkInAz]

When the machine is turned on for the first time in a few days it comes on showing error "6" in the display.  After about 5 minutes it changes to 50.000 by itself.  Then after coin-up the machine it will show error "6" when you pull the handle but quickly gos back to 50.000 buy the end of the spin and the Tilt lights up.  If you wait another 5 minutes eventually the errors will stop and you can play the machine all day with no problem. 

I've already changed out the RAM chips (M1, 2, 3, & 7) and inspected the CPU and IO boards under the scope for cold/damaged connections and cleaned all the board connections and chip sockets.  The NiCad battery checks good holding at 3.6VDC when the machine is off.

Suggestions?

[dhellis]

You might want to try replacing C3 which sits next to the reed relay. C3 is a 33 mfd 25 volt electrolytic
and sits in the reset circuit.

The coils of the relay are shown in the Low Voltage detect, one of the contacts of the relay goes to
pin 11 of U5, the other side goes to pin 3 of U26, pin 4 of U26 (an inverter) generate the reset signal
to the CPU chip, that same relay pin also goes to the reset of the CPU chip (pin 16)

I have seen many strange problems caused by C3

[MarkInAz]

OK so you think its the reset signal staying/going high?  I'll have to poke around this area with my scope and see what's what. 
Also, any idea where pin 1 of J3 is coming from? Low voltage of what? I assume it's the +5 power supply as VR-1 is a 5V zener? Funny, I have yet to figure out where one finds the chassis wiring info on these old Ballys.

Cheers,

Mark

[GOS]

I have found the 6 error usually is the power supply.

[dhellis]

I have found the 6 error usually is the power supply.

This very true and since the problem lasts for about 5 minuets I would suspect the
large capacitor. However these power supplies also have known issues with the plugs
so it might be a good idea to order this and replace it.

http://www.ebay.com/itm/Bally-Slot-Machine-E-Series-POWER-SUPPLY-CONNECTION-/350252825206?hash=item518cb1fa76:m:mnkXSbJHsnwjhO2XCor5Mng

[Jon]

if there is a burned terminal on that plug you will need to replace the male part of the plug on the power supply board or replace the power supply board as well as the plug usually I have found the second third or fourth terminal up from the bottom of that plug is burned and that's what causes the six in the display I replace both the Molex plug and the terminal I order mine from Fry's Electronics the plug comes as two tens instead of a 20 for about 3 bucks the terminals come two tens for about $2.25

[dhellis]

OK so you think its the reset signal staying/going high?  I'll have to poke around this area with my scope and see what's what. 
Also, any idea where pin 1 of J3 is coming from? Low voltage of what? I assume it's the +5 power supply as VR-1 is a 5V zener? Funny, I have yet to figure out where one finds the chassis wiring info on these old Ballys.

Cheers,

Mark

I don't really know where the low voltage detect is coming from, the schematic shows that it goes to pin 1 of J3 but does
not show where. The manual that is used to repair these boards just states that the low voltage switch is either at ground
or will go to 10.5 volts so perhaps it goes to the power supply since that is the UR voltage.

[MarkInAz]

Thanks Jon & Dhellis for your input.  Lucky for me there is no damage to the J1 plug or pins on this machine.  When I get a chance I'm gonna measure the power supply voltages too and see what those are reading.  I can see all the electrolytic caps are originals so that's suspect for sure.
On a side note I find the MPU schematic on the 1000 and 2000 rather interesting.  Like that Rf detector/antenna that is tied to the reset line via a 555 timer. What the heck is that all about     It would be nice if I had documentation on the MPU board.

BTW here is what I found on my MPU board.  I have never seen chip legs loose there plating before. Took a lot of effort to clean it all up.

[dhellis]

The "Antenna circuit" is there to prevent excessive radio interference as it will cause a tilt. My best guess is
that this was implemented to deter cheaters. Other than that I see no practical reason.

The documentation on how these MPU's are supposed to work is either not available or perhaps
difficult to find. The board schematics are in FO-650-13 and then there is a manual for test procedures
FO-650-1. This manual is meant to be used with the Bally K-661 tester. The tester has a board simulator
and also need to have the signature analyzer.

The simulator repeats known cycles so from there you know exactly what you should expect to
see at each test point, for an example the first test is pin 1 of U29, the analyzer should read P9AH.
If a test fails, the manual does have a good flow chart for trouble shooting and shows which components
are involved.

I use to fix these things but something has gone wrong with the tester and every board that
I put on it seems to have the same problem. I have also had no luck in finding what the problem is.

[MarkInAz]

I've read a couple other posts about the K-661 tester.  What does it look like??

[rokgpsman]

...On a side note I find the MPU schematic on the 1000 and 2000 rather interesting.  Like that Rf detector/antenna that is tied to the reset line via a 555 timer. What the heck is that all about?

When slot machines made the transition from purely mechanical to electronic there was a lot of worry about people possibly being able to influence the circuitry inside the machine with homemade rf devices. The same thing happened when people tried to use rf transmitter devices to jam police radar so they'd avoid a speeding ticket. In theory it may sound plausible, but in actual practice none of that stuff works as far as I know. But in the casino industry there is a lot of money at stake, and no slot machine company wants to be blamed for inferior design that causes the loss of money to the casino, so the Bally engineers added that antenna circuit to detect if someone is using an rf transmitter nearby. The antenna is usually simply a circuit trace (path) that runs around the edge of one of the circuit boards near the front of the machine where it would have the best chance to pick up any rf signals from the player. The antenna trace is connected to a pin on that board's connector and sent over by a wire to the mpu board.

They thought it was a serious enough threat that it was also used in later designs. Here is a portion of the Bally S5500 mpu board reset circuit, you can see that it also has an antenna input that would reset the machine if rf signals strong enough were received. They had jumpers that you could remove to disable the circuit because in some locations it would cause nuisance reset problems.

[dhellis]

Here is a photo of the tester.

[MarkInAz]

Excellent explanation of the need for the RF circuit Rokgpsman. And cool photo Dhellis. 

[MarkInAz]

Dehellis you were right on- my Error Code 6 is being caused by the reset signal pulsing high for the first 5 minutes after power up.  However I'm having trouble isolating the exact cause as my scope probe is loading the circuit causing the problem to disappear when I connect it. I'll get it eventually.  Thanks for the tip 

Cheers,

Mark

[dhellis]

Dehellis you were right on- my Error Code 6 is being caused by the reset signal pulsing high for the first 5 minutes after power up.  However I'm having trouble isolating the exact cause as my scope probe is loading the circuit causing the problem to disappear when I connect it. I'll get it eventually.  Thanks for the tip 

Cheers,

Mark

Mark
The reset circuit consists of U5 pins 11,12 and 13 and U26 pins 3 and 4. There is a small transistor (Q3) that feeds
pin 12 of U5, and then there is the relay as well as the previously mentioned C3.

Since your scope eliminates the pulsing then you have to think that this is a capacitance issue
so perhaps check C3 as well as C4.