(Topic ID: 195975)

Space Station blows fuse

By Billc479

2 years ago

Topic Stats

  • 16 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by Billc479
  • Topic is favorited by 2 Pinsiders


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SpSt sols1 (resized).png

#1 2 years ago

I'm working on a Space Station, and it began blowing fuse F4 on the Aux Driver board. Installed was a 2 Amp Slow Blow fuse. I've checked the resistance on all of the coils that F4 is associated with - If I'm reading the manual correctly, they are Solenoids 3A, 4A, 6A, 7A, 13, 17, 18, & 20. The coils seemed to read around 8 - 15 ohms each, so I don't think they are bad.

One of the things throwing me are the transistors associated with the solenoids - I can't seem to locate them. I feel like a novice! So where are the driver transistors located? I don't see them on the aux driver board - Am I overlooking them? Thanks

#2 2 years ago


If you go to IPBD, the manual for this pin can be downloaded. Have a look to the very beginning of it, the transistors Qxx are indicated next to each solenoid in the solenoid summary. Your assumption regarding the solenoids id is good, according to the connector by board schematics in the manual. Make sure you check also the triggering transistor, which is the little one next to the driver transistor ( grounding the circuit).

Try to remove the female connector J12 on the Aux Driver board and see if your fuse still blows. If not, you have a short with the coils or under the PF. If yes, the problem is on the boards.
Also check the voltages VDC on the J12.

#3 2 years ago

SpSt sols1 (resized).png

That's the best I can do with the online manual. Can't read anything on the CPU drawing.

#4 2 years ago
Quoted from Billc479:

One of the things throwing me are the transistors associated with the solenoids - I can't seem to locate them.

When Williams added the Aux power supply they added 8 Tip36a transistors to switch high current coils instead of snubber relay boards. For this game coils # 3a 4a 6a 7a 13 and SPL #2 and #4 are controlled by both the CPU transistors and the Aux power supply transistors.

cody_chunn posted the page from the manual which shows the CPU transistors for the coils you are testing. And page 61 of the manual shows the other 8 transistors on the Aux power supply.

For example to troubleshoot coil 3a you need to test transistor Q-32 on the CPU board and Q-1, D-3 on the aux board for shorts that would lock on a coil and blow the fuse.

You can divide the number of coils in half by removing J12 on the aux p/s and testing for ohms on pin 6 and pin 12 of the connector to ground. One of this pins will read low ohms @ 1-2 ohms.

#5 2 years ago

Thanks all. I will report back. I did not realize the driver transistors were on the CPU. I did not find Q75 on the CPU schematic, but I'm sure I will find it on the board.

#6 2 years ago
Quoted from Billc479:

I did not find Q75 on the CPU schematic, but I'm sure I will find it on the board.

It is on page 1 of 4 on the right hand side of the page. The 6 SS TIPs are in a group by the flipper relay on the CPU board.

#7 2 years ago

Remove the plug J12 of your aux driverboard and see if the fuse blows again !

#8 2 years ago

If not you have a problem on the playfield ( solenoids )
If the fuse blows again you have a problem on the aux board

#9 2 years ago

I've tracked the problem to the "Left Ball Popper", solenoid 3A. The aux driver board components checked out OK (Q1, D3). On the CPU, Q32 checks bad. I am going to change it tonight, along with the pre-driver, Q28, as a precaution.

Grumpy, maybe I'm looking at a bad copy, but the TIPs I see are Q78, Q71, Q73, Q69, Q77, and Q79, top to bottom. The numbers are pretty hard to read- it looks like IPDB has a copy of a copy of a copy. Thanks for your help - I really appreciate it.

#10 2 years ago

Here is a tip, system 11 boards are basically the same so you can use schematics for the CPU from a game that the printing is better. So try WW set.

#11 2 years ago

Tip #2 replace Q-32 with a TIP 102 instead of a TIP 122 as it is 60 percent stronger. And any time a coil locks on long enough to burn the fuse you need to replace the diode and check the coil and sleeve.

#12 2 years ago

Grumpy - Thanks for the tip. Unfortunately, I've already put in a 122.

The coil locked on again, so I disconnected the solenoid, and started troubleshooting again to find out why the coil was locked on. I finally found U20 output was high going to Q28 (Q32 predriver). (Pin 9 low. pin 10 high, pin 8 high) Compared that AND gate to the others on that chip, and that was the only group with a bad output. So. I'll change it and try again Wednesday.

We've got a campsite in Southern Illinois for the eclipse and will wait until Tuesday afternoon to leave - hoping that traffic will be more manageable.

#13 2 years ago

Tip #3. I always pull the fuse for the problem coil before testing. After powering on the game I then check for problems by touching the fuse to the holder. If it sparks then I have more work to do.

7 months later
#14 1 year ago

Billc479 Did you ever resolve this? I have the exact same problem. Q32 and q28 test fine for me as well. The aux board components test fine too. If your u20 tested bad did you replace it and that solve the problen?

#15 1 year ago

Also, the lf ball popper will fire 1 or 2 times then blow the fuse.

#16 1 year ago

I replaced U20, it still didn't work, so I sent the board to Chris Hibler. What he found was that I had replaced U20 with a remarked chip - he replaced U20 with a real chip, and the board worked fine.

I had that chip in my tool bin for 10 plus years, so it must have been an early counterfeit chip. Looking closely at the chip, you can see where the old part number was ground off, and a new stencil marking was added on top of the poorly ground surface.

I now look closely at all my chips before installing, and I only buy from GPE - Ed goes through great pains to make sure what he sells is the real thing.

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