Intermittent Flashers on Indy

[robm]

On my Indiana Jones the flashers have just started to only work intermittently.  Yesterday (and for months previously) they were working fine, and i decided to level the playfield.  I left the machine on (unsure why?), pulled the glass off and put the spirit level on the playfield - didn't touch any switches or anything that i recall.  The machine was moved a bit as it was lifted to wind the leg levellers.  We did not lift the playfield or remove the backglass at all.

Put the playfield glass back on and noticed that none of the flashers worked during the next game - the sounds came on for jackpots etc, but no flashers.

Today i did the flasher test in diagnotics and nothing worked.  Started a game and they started to work, at 1st the quick multiball one worked, then the path of adventure one didn't, then once i got to 3 ball mode they all started working.....

Then partway through the game, when the quick multiball flasher should have worked, the appropriate sounds came, along with the mode on the DMD, but no flasher.

Suggestions as to where to check first for these potentially painful intermittent problems?

[robm]

I also just noticed that the flashers on the plane gun LED's work all the time (ie: in flasher test and in game when others are not).

Does this give any clues as it is wired a little differently?

I have reseated all the plugs in the diagram with no difference.

[ajlaird]

I guess the first step would be to check continuity between the driver PCB and the flashers. Use a multimeter on continuity setting (or low ohms range) with the machine turned off.

Second step would then be to ensure that signals are making it to the driver board from the CPU board.

[Chuck]

Those molex connectors to the driver board are generally pretty crappy at best. Like suggested check the continuity. I would suggest pulling each molex and checking by sticking your probe down in the connector. The failure usually occurs where the wire is forced into the steel connector. If this is a bad connection I suggest removing the old connector and using solder pins and a new molex connector. That will make a much better connection.

[robm]

An update, there is continuity between the J107 connector on the power driver board and all the flash lamps.  When tested this had the required 20V, as does test point 7.  Below is an extract from pinrepair...

LED5/TP7: +20 volts DC flashlamp circuit. Normally ON. Twilight Zone and later, this LED fades off when the coin door is opened. If off, check coin door and fuse F111 (or bridge BR4 and capacitor C11). The AC Power originates at connector J102 pins 1,2 and 3,4. It then goes through fuse F111, bridge BR4, capacitor C11, LED5/TP7 (20 volts DC), then to connector J107 pins 5,6 (and J106 and J108).


From what i figure U3 (an LS374 IC) controls the flashers, so i am assuming this may well need to be replaced.

Another intriguing factor is that the LED5 (associated with test point 7) stays on for a minute or so after powering the machine off.

Is there anything else i can test to confirm U3 is the problem or does the LED staying on suggest something else?

[The pinballist formally known as Dean Morgan]

When you tested J107 to the flash lamps and it metered Ok, did you then test the flash lamps and they were working?

I doubt U3 would be intermittantly faulty (it is possible, but low probability).  More than likley a loose connection or bad solder join would cause the fault you describe.

If it was all the flashers excluding the Plane Gun that didnt work then this points to the 20v being missing.  So most likley a connection somhere or a bad solder joint or connector on the power driver/supply board that provides the 20 volts to J107.

[robm]

Thanks for the reply - i will go and double check all solder joints, but an initial glance they all seemed OK.  The problem is now permanent...is it possible the chip could have been on the way out when the problem was intermittent or do they just go?

[The pinballist formally known as Dean Morgan]

Thanks for the reply - i will go and double check all solder joints, but an initial glance they all seemed OK.  The problem is now permanent...is it possible the chip could have been on the way out when the problem was intermittent or do they just go?

If the problem is now permanant test between the J107 pin 6 and ground for 20V.  If this is missing the problem is before this point at the power supply. If it is there, then test again for it at one of the flashers under the playfield.

[ajlaird]

Fading off could describe the LED staying on for a while before it fades out.

Redo the soldering to U3 as a next step after doing what Dean suggested, or take it out and put a socket in place if you want. That way if it is faulty you can replace it easily enough.

[The pinballist formally known as Dean Morgan]

Without seing the electronic schematic for the LED, I would say it is only staying on for a little while after power off due to capacitor discharge.  This would be normal and not related to the fault.

[The pinballist formally known as Dean Morgan]

The fact that the led is on would indicate that the 20v at the power supply is Ok.  Howver, could still be a connector from the power supply to J107 - 6.

[ajlaird]

Without seing the electronic schematic for the LED, I would say it is only staying on for a little while after power off due to capacitor discharge.  This would be normal and not related to the fault.

Yeah, that is the case as there is a 15000uF capacitor in parallel with the LED and voltage drop resistor - and probably the LED fades off in the same way when the coin door is opened.

[The pinballist formally known as Dean Morgan]

Without seing the electronic schematic for the LED, I would say it is only staying on for a little while after power off due to capacitor discharge.  This would be normal and not related to the fault.

Yeah, that is the case as there is a 15000uF capacitor in parallel with the LED and voltage drop resistor - and probably the LED fades off in the same way when the coin door is opened.

Yeah, agreed

[ajlaird]

The fact that the led is on would indicate that the 20v at the power supply is Ok.  Howver, could still be a connector from the power supply to J107 - 6.

Having read the schematics in some more detail I am almost convinced that the problem has to be either the LS374 or the connection to J107-6 (20V line).

Here is what we know so far:

The problem is present on all flashlamps that run off J107-6. There is confirmed continuity between J107-6 and the flashlamps, and the 20V tests OK at TP7.

Now, I have to assume that there is a separate circuit for each of the flashlamps as each can be driven individually. However, all playfield flashers (8) could fit on to one LS374 (8 flip-flops) so I guess they all use the same LS374. There are also another 5 flashers driven off the 8 driver PCB and not the power driver PCB like the other 8. These 5 are the LS, RS, Special, Totem Multiball and Jackpot Multiplier flashers. If these don't work it has to point to J107-6.

While there is continuity between J107-6 and the flashlamps, it is possible that the connection is not great (yet still showing continuity) and is causing a large enough voltage or current drop that the flashers are not being driven.

[The pinballist formally known as Dean Morgan]

The fact that the led is on would indicate that the 20v at the power supply is Ok.  Howver, could still be a connector from the power supply to J107 - 6.

Having read the schematics in some more detail I am almost convinced that the problem has to be either the LS374 or the connection to J107-6 (20V line).

Here is what we know so far:

The problem is present on all flashlamps that run off J107-6. There is confirmed continuity between J107-6 and the flashlamps, and the 20V tests OK at TP7.

Now, I have to assume that there is a separate circuit for each of the flashlamps as each can be driven individually. However, all playfield flashers (8) could fit on to one LS374 (8 flip-flops) so I guess they all use the same LS374. There are also another 5 flashers driven off the 8 driver PCB and not the power driver PCB like the other 8. These 5 are the LS, RS, Special, Totem Multiball and Jackpot Multiplier flashers. If these don't work it has to point to J107-6.

While there is continuity between J107-6 and the flashlamps, it is possible that the connection is not great (yet still showing continuity) and is causing a large enough voltage or current drop that the flashers are not being driven.

Agreed, we need to know if all the flashers bar the gun are not working.  If this is the case it needs to be a problem on the 20 volt line.  Connection from power supply to J107-6.