1994 Double Jackpot questions

[Pitts256]

On the LED display board there's a couple of driver chips, 74LS247's or 248's. One could be bad.

Check the wire plug to the board. Could be a broken wire, oxidation on the pins or a loose pin on the board.

The main CPU board may have a flakey LED cathode driver chip, like a ULN2003.

[Thephoneman]

Will do

[Thephoneman]

So I'll be checking those things Pitts, but this fault out that I keep getting is driving me nuts. So what is doing is kicking out  the coin comparator, and the led display. Have to reset it (sometimes  multiple times) it comes back fine and then kicks back out after a few minutes. I have left it on to while it's been doing this. I did replace the voltage regulator and is still feeling pretty warm.  Also bypassed the noise filter in the power supply but that hasn't changed much (haven't heard the squeal lately). 

[Pitts256]

Interesting...

So what do the LED display and coin comparitor have in common? They share the same logic data path and use power from the supply. The coin comparitor uses 32vdc while the LED's use 5vdc. The data lines are used to control multiple functions for the entire machine and the machine doesn't appear to be out of control so I'm thinking you have a power supply issue.

Coin Comparitor Check:
I was looking at the photo you posted of the comparitor and is the white wire from the comparitor plug connected to the BLUE (pin3) or VIOLET (pin 2) wire and the Black wire to the Black wire (pin1) on the CN-39 plug?

The 5vdc voltage regulators run hot, close to 150 deg.

Since you're hearing a squeal there's a probability that one of the filter capacitors in the power supply is failing and allowing ripples to pass. Monitor the output voltages for variation. The 32vdc cap is a 6800mf-35v and the 5vdc uses a 22000mf-16v or 2 10000mf-16v in parallel.

 

[Thephoneman]

That does make sense. I'll see if I can figure some of this out but I'm not sure where all of these points are at.  I can post better pics of coin comparator and power supply if you want so you can guide me a little better. My knowledge on these is starting to get strained lol. And with it being a later model,  I don't know if my manual has these specifics.

[Thephoneman]

So as I continue to tinker with it,  I'm pretty sure there is a power supply issue.  Not sure if that is what's causing the 7 segment display.  So I've looked in the supply and it has the can capacitors as well as a few other items that I dint know the names of.  It's started to blow a fuse (i think it's 9.5v 5a). The fuse was loose and I tightened up the holder for it.  I might just replace all 3 caps and go from there. I'm not a expert by any means so I appreciate the tolerance of me asking all these silly sounding questions.  I can post a Pic later if needed.

[Chris-socal]

Its always a good idea to replace electrolytic capacitors. Not many other components on a power supply go kinda bad. They usually work or not. Capacitors on the other hand can cause variable issues.
Fuses are usually 250volt, not as important as the amp rating. 9 amp seems odd. The value would usually be printed on the board next to the fuse or stamped on the fuse end cap.

[Thephoneman]

I can get the proper numbers when I get home.  But those caps look like they are attached at the bottom by screws? And then just a simple connection on top.

[Chris-socal]

The capacitors are soldered to the board….in most instances soldered to the bottom of the board. Voltage rating on capacitors is very important. You can always use a higher voltage rated capacitor but never lower voltage.

[Thephoneman]

I can't thank you enough for the help and insight. I'll get more accurate info later today.

[Pitts256]

So the 9.5vac 5amp fuse is for the supply to the CPU for the 5vdc. The CPU also uses this voltage to monitor whether the power supply is functioning correctly.

When you order the caps for the supply make sure the values are the same and also check the size, it's tight inside the supply case and the cap diameter and height are critical.

[Thephoneman]

So the fuse that keeps blowing is the AC 9.5V 5A DC 5V (4th fuse from the top. I just did it again while trying to reset the mystery fault. Held the reset button, cycled the power,  heard the comparator click once then clicked again and it blew.  I'm going to get a Pic of it in a sec. 

[Thephoneman]

So here is the psu opened up.  The front is to the top of the pic.

[Pitts256]

The 3 caps circled in the photo below are the ones to replace. These are polarized caps with solder lugs.

If the 5vdc is "dirty" due to a failing capacitor then that would explain why the CPU logic is flakey. Monitoring the 5vdc output with a scope could eliminate the supply as being the issue. If the 5vdc output is clean then there's an issue with a logic chip on the main board.

The coin divertor solenoid on the door, just below the coin comparator, pops closed when the CPU boots up. First step is 32vdc is applied to the coil to close the divertor then the voltage drops down to 12vdc to hold it closed. The only time that divertor should be open is if the hopper is full of coins high enough to make contact with the high level probe.

[Thephoneman]

I have those 3 caps on order. Hopefully that gets me somewhere. Thanks again for all your help pitts!

[Thephoneman]

Well replacing the capacitors has not fixed the problem  Still faulting out.  Needing several on off resets to get it back running. Did manage to get it to fault mid spin, and the reel music kept playing.So I'm not sure if i need to replace non specific to the machine chips or what.  It is playable but hate it cutting out possibly mid game. 

[Thephoneman]

A little more clarification to help with my issue. So I have the ba piggy back board and it usually flashes e21 on it.  When it faults out it goes between e21 and 300 but the 0's look like backwards c's.

[Pitts256]

With little information available on the BV and SUB board it's guesswork. The SUB is a communications board and I'm thinking the error is for a loss of comm to the BV head. I'd have to trace the two harnesses coming off the board to the opposite ends. Does the BV head cycle at startup? If it's not making it through the startup test cycle then it will throw an error.

It's looking like a logic chip is giving you some problems. If you can narrow the glitch down to one specific part in the machine I may be able to recommend what chip(s) to check-change. Again guesswork without the 8800 schematic.

Something we want to avoid though is running the machine with flakey logic chip. If a solenoid coil doesn't change state per the program logic, like the coin divertor, the coil will overheat and short, then go back and take out a driver transistor on the CPU board.

       

[Thephoneman]

I hope I've been giving accurate info since most of the posts are while I'm at work and have been stewing over it lol. I'll have to go thru this thread and make sure all of my issue info is accurate. I dint want anyone who's willing to help go Duran the wrong path issue wise. 

[Thephoneman]

So after looking back thru this thread,  I see where the fault out issue started. The chip that had the red wire attached was "missing" a pin, so i replaced the chip.  I've undone that (bent that pin out) and will let it sit for a while and see if that resolves that issue. I also located the sound board in the meter box on the right hand side of the reels.  Tired to sand the point where that meets the chassis but still get that squeal. Looks like there are 4 small blue can caps as well as the amp ic. I'll see if the electronics store has those and replace them.  So hopefully we'll be down to the display issue.