I recently picked up a 79 Flash (my second pin) and am having some difficulties with the left slingshot. The pin had been treated somewhat poorly previously, for instance there were womens hair ties in place of rubber all over the darn thing. As well as ugly fixes here and there on the back of the playfield, and completely warped/cupped inserts across the pin. Someone had also introduced the 'mini' ball for the tilt sensor into the playfield for a 'multiball' effect which the seller stated 'didn't work properly'

Anyway, when I got it the left slingshot coil was frozen, upon removing it I could see it had completely melted (or at least the sleeve did). The solenoid fuse did blow at least, and upon replacing it all the other solenoids work as expected. I replaced the coil with a new one, but it never triggers when the switches are activated on the playfield.

Next up I tested for voltage and got around 23V on it and the other solenoids, so thats good. So then I grounded the new solenoid on the non-banded lug and it fired, but it stuck on immediately -- which is probably how the last one melted. For some reason I freaked out at that moment and then grounded the other lug which unstuck the solenoid.

So now I'm not sure where to go from here. The 'special solenoid' transistors visually look fine, as I partially expected one to be visibly blown but was pleasantly surprised. To be frank I probably don't want the switches to 'work' until I figure out why the coil stuck in the first place (and continues to do so when grounded). In a nutshell:

1. Left slingshot coil was melted
2. Replaced coil, solenoid won't fire when switches are hit on the playfield
3. Grounding the non-banded lug fires the coil in question, but it sticks on at that point.
4. In solenoid test mode, this coil doesn't fire

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I should also clarify cuz this is probably useful info.

In solenoid test mode, the coil in question does not fire.
In Switch test mode, the switches in question do not register either when pressed on the playfield. Will update OP accordingly.

Tried clipping one of the legs of the cap, the coil still stuck when grounded.

Would a bad transistor or pair of them cause the coil to stay stuck on when fired manually by grounding the coil as well?

Ok so small update. I put the machine into switch test mode again, and the right kicker/slightshot switch did register, which would lead me to believe the left switch should register in switch test mode as well (it did not). Continuity tested correct on the switches.

So I then pulled the contacts off the switch matrix headers, and manually tried to see if it would recognize the switch if I selected the correct row/column. It appears to work, as when I touch row 3 and column 8 (last pin on the bottom header) it registers #41 which is what I think it should be registering. So I think that means the switch matrix is probably ok, and there is a wiring issue as to why its not picking up the left kicker/slingshot switch.

I am still at a loss why manually firing the slingshot coil by grounding it results in it being stuck on, as I'm fairly certain that action does not involve the transistors on the driver board at all.

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I did a quick and dirty test just now by connecting the negative to the ground strap, and then touched the positive lead to the metal tab on the large TIPs, and confirmed none of them were shorted via a continuity test. But I know thats not an end-all test and might not tell me much without testing each one individually -- which I will try to get to tonight.

Ah ok this makes sense, so all I really did was validate that the 'scoring' switch underneath the playfield works. I see now why I made that mistake, pressing the above board switches for the right kicker in switch test mode activates the coil, which then pulls down and flips the scoring switch. Doing it manually with the plunger on both left and right kicker/slingshots does indeed register on the switch test. So my switch matrix test I did earlier was a waste of time

I'm going to try and fully test each transistor tonight. My quick and dirty test may not be sufficient as all I know is that they aren't completed shorted to ground. I have new some TIPS on the way from pinballwizard I ordered ahead of time in case of this, but I forgot to order the smaller pre-driver transistors, I need to look those up still.

I just double checked my pinball wizard order, I actually ordered a half a dozen TIP102s and 2N4401s, which I think will work for the pre-driver transistor as well! So...I got lucky there! Time to wait for the mail I guess. In the mean time I'll hope to test them all tonight.

Just a small update, the Q10 and Q9 transistors tested bad, which I think is a good sign since they are tied to the kicker/slingshot in question. I went ahead and pulled them and am now just waiting for replacements to arrive. The resister above Q9, R20 visually looks burned, however it seems to test ok at 68 ohms. I suppose I'll leave it for now.

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Well shoot. I replaced the Q9 and Q10 transistors, and immediately upon powering the machine the coil locks on (which I can only assume happened previously hence the melted coil I found).

On the plus side this is new behavior since I've gotten it, so the new transistors are definitely doing something, but I'm going to have to unsolder the coil so it doesn't melt at this point.

Anybody have any further ideas what could cause this? I'm sort of running out of ideas, the coil and diode are brand new so its unlikely the diode is bad. And its clearly happened in the past as well (and burnt the corresponding transistors in the process). My next guess is the 7408 or 7402, but man I hope it doesn't come to that. Any other possible things I could've missed that would lead the coil to lock on?

Unfortunately I don't have a logic probe. Based on the schematic it looks like the next in line is a 7402N, and downstream from there a 7408PC.

I read in another older thread someone mentioned once a pre-driver transistor sticks and the coil locks open (and potentially melts) it does massive damage to the ICs downstream quickly, so its probable thats what happened here.

Does anybody know a good source for these? I see Jameco has a regular 7402, I assume this would work for the 7402N. https://www.jameco.com/z/7402-Major-Brands-IC-7402-QUAD-2-INPUT-POSITIVE-NOR-GATE-DIP-14-pin_49015.html

They also have a 7408, which I'm hoping somebody can confirm will work instead of a 7408PC https://www.jameco.com/z/7408-Major-Brands-IC-7408-Quad-2-Input-Positive-AND-Gate_49146.html

If those are good I guess it would make sense to just get the sockets as well if I'm going to be taking the chips out. I think these would fit. https://www.jameco.com/z/6000-14DW-R-Socket-IC-14-Pin-Dual-Wipe-Low-Profile-0-3-Inch-Wide_112214.html

If anybody can confirm that would be great!

Edit: Also, does anybody have a higher res version of the schematic/manual than this? http://antelopearcade.com/files/Pinball%20Schematics%20and%20Servive%20Bullitens/FLASH_MANUAL_AND_SCHEMATICS.pdf or this one? https://www.ipdb.org/files/871/Williams_1979_Flash_Manual.pdf

Its really tough to read some of the schematic portions as they are blurry when zoomed in.

Thanks for the schematic info! Bump if anybody can confirm the ICs would work listed above.

Bumping again for any input on where to find the correct ICs.

Unfortunately Ed didn't have everything I needed so I ended up ordering from Jameco. I'll let you guys know if it fixes the issue in a week or so when I get them. Thanks for all the help so far!

And its Fixed! Swapped out the 7402 with a socket and a replacement, and the left slingshot/kicker is back in action! Thanks for the help as always guys!

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