I have a project Space Shuttle machine that I have been troubleshooting a few issues on. Most of them have been resolved but a couple really annoying ones remain:

-The ball trough eject (solenoid 2) tries to fire to eject the ball into the trough but just sits there and keeps weakly trying, quietly clicking. If I manually give it a nudge from below, it will fire out the ball. I have 3 balls in the game and have tested the 3 trough microswitches which are all working. The transistor tests good and was replaced anyway for good measure. The assemblies are all tight and appear to be aligned well. The coil/diode also tested good but was replaced for good measure. The same exact problem continues to occur. I even tried swapping a separate known good Sys9 board into it and it does the same thing. Any ideas?

-Also, the bell is causing me some confusion. It appears to be wired fine and dings fine during the solenoid test. However, when it fires during the game it causes an annoying buzzing-type sound, definitely not a bell ring. I watched it while it did this and the striker seems to hit the bell and just lock on, instead of going back and forth. I'm not experienced with bells so I'm not sure what this could be...

Any help would be appreciated. Thanks!

Thanks for the response. I previously checked the voltage and it was 28v but I'll check it again to make sure it's consistent. The coil/sleeve/diode all seem totally fine, even the one I swapped out. The whole mechanism moves very smoothly by hand, no resistance at all.

I'll go through the other coils again too and check them closer. Thanks again.

Awesome tip, I'll check it out. Thanks!

I connected a jumper wire to ground and then to the control wire and it fires hard every time! So, my problem is in the control wire path somewhere. I get continuity between the control wire on the coil and the board connection. I re-pinned the old IDC connector with a solid Molex one and the problem remains. The transistor has been replaced on the board and tests good. It's like something isn't making a good ground connection where it should be. Any further ideas?

Oh, on the bell: I spent some time adjusting the metal piece that strikes the bell and now it works consistently. Woo hoo!

Yes, I have the manual. The transistor has been swapped and gets the same readings as the surrounding ones. If the transistor was bad, would the coil still try to fire? I can hear (and feel) it trying to fire very weakly. I can definitely try another transistor if that might help.

Thank you so much for the detailed info, this will help me a lot! Sounds like I have a fun weekend project ahead of me.

Oh man, I feel like I'm getting closer! Here's what I found so far from your instructions:

U-46 pin 2 has high pulses
U-57 pin 12 has high pulses
U-57 pin 13 has a high signal
U-57 pin 11 has low pulses (not correct per your instructions, they should be high pulses)
Also checked the base leg of Q-44 and it is low signal.

So, would that mean that the problem is in U-57 or would it do any good to try changing Q-44?

Thank you!
Brent

I'm getting .554 ohms between SR1 pin 3 and the +5v.

With the power on, I get 5v on pin 1.

I'm using the "2k" ohm setting on my DMM for ohm testing on SR1. With a lead on pin 1 and going down the line with the other lead, I get roughly .555 ohms on every pin, except pins 6 and 7 only show about .225 ohms each.

I'm reading it as .5 ohm but as you can tell, I'm a newbie to really digging into troubleshooting the board components. It looks like SR1 and 2 have been replaced at some point. Is it possible that it may be installed backwards? I assume there's a pin 1 mark but the printing is so faint I can't really tell. Weird about the lower readings on pins 6 and 7 though...I checked them several times.

I ordered some parts from Marco and replaced SR1 and Q44. SR1 now is getting 560 ohms all the way across. The ball trough issue remains so it's probably U-57. I ordered a 7408 IC to replace it but they sent me an IC stamped 7402N, so I'm a bit worried it's not the correct one. I emailed them about it to get more info. Other than this one remaining issue, the game is playing really well.

Thanks for all your help

A couple of the legs measured bad but it was the right part. Marco is sending me a 7408 IC so I can replace U-57.