F-14 Upper Diverter Solenoid Stuck On

I’ve had this machine for a while, but I’m finally finding time to put some work into it. When I bought it about four years ago, the upper diverter coil was sitting, somewhat scorched, in the bottom of the cabinet. I bought and installed a replacement, and noticed very quickly that it was stuck on when the machine was powered up. So as not to do any further damage, I disconnected power to it. I did some searching around back then but I couldn’t really get my head around the problem, and I was scared of board work, so that is where I left it.

Fast forward a few years, and I’ve re-initiated my search of the forum to try and solve this problem. There are obviously quite a few posts already about similar issues, but none seemed close enough to mine for me to figure out the best way to troubleshoot and correct my specific problem. I have a DMM and know how to use it, if there are things that I can test to isolate the issue. Because I’ve never had it working properly, I’m not really sure what the theory of operation is for these diverters. I believe they they are controlled by special solenoid #6, but do other switches (perhaps the switches under the other ball lock positions) control this? I don’t think that I have any stuck switches, but I can certainly verify.

Any help would be greatly appreciated!

#2 6 years ago

LTG

Pinside member

Hopkins, MN

12y 191K 56,985 24 7

I'd replace the transistor that drives it. Easy to check with a DMM, compare it's legs with other identical transistors near it. See if it's shorted.

Manual can help identify which one to check.

LTG : )

#3 6 years ago

SAM

steve8091

Pinside member

I checked all of the transistors in that area, including Q77, which is the one that I believe drives the upper diverter, with my DMM. I checked for resistance/continuity between each pair of legs, and they all seemed to come out about the same (they'd jump to 60/100 for an instant, then show discontinuity). To be honest I'm not 100% confident in what would differentiate between good and bad (I assume a bad transistor would show continuity between a pair of legs), but again, they all seemed about the same. I pulled the board out to get a closer look, and quickly discovered that this is going to be beyond my ability to repair. There have actually already been repairs in this area - pics below. It looks like Q76 and Q77 (which drive the upper diverter), U50, and possibly Q79 have all been replaced before. There was also a jumper added between one of the legs of U50 and Q67. I'm afraid that I'd end up soldering all of the traces together if I were to attempt to repair it.

I'll search as well, but do you all have any suggestions for who might be able to perform the repair? I'm in NE Wisconsin, so it might be tough to find someone local.

IMG_2114 (resized).JPG
IMG_2115 (resized).JPG

#4 6 years ago

LTG

Pinside member

Hopkins, MN

12y 191K 56,985 24 7

OP
Quoted from steve8091:
I'll search as well, but do you all have any suggestions for who might be able to perform the repair? I'm in NE Wisconsin, so it might be tough to find someone local.

Post on the Wisconsin Minnesota thread and maybe someone close to you can help.

LTG : )

#5 6 years ago

AMS

barakandl

nvram.weebly.com

12y 132K 10,417

I had a diverter coil lock on in my F14 and not blow the fuse until things really burned up. I had to replace two logic chips (7402 and one more I can't remember), the 2n4401, and the tip102.

I also see 74LS02 chip... I don't think you want to be using the LS logic family in this circuit. Use 7402 plain or 74F02. Luckily it is in a socket already.

With a logic probe you can figure out if the chips are working. Pull the solenoid power fuse and you can use test mode. Compare to working circuits.

#6 6 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

OP
Quoted from steve8091:
I checked for resistance/continuity between each pair of legs, and they all seemed to come out about the same (they'd jump to 60/100 for an instant, then show discontinuity).

Did you have J19 disconnected when you tested this. Now that the board is out you can retest pin 2 to 3 on the TIPs and compare to the others.

You should test ZR-8 for being shorted too.

OP
Quoted from steve8091:
There was also a jumper added between one of the legs of U50 and Q67.

This is because of the socket that was installed, there is a cold solder joint on the top of the board at pin 10.

If the Tips and ZR-8 check out OK then reinstall the board and leave 1J19 off and use a logic probe to continue testing.

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#7 6 years ago

SAM

steve8091

Pinside member

Thanks for the replies.

Quoted from LTG:
Post on the Wisconsin Minnesota thread and maybe someone close to you can help

I did and got hooked up with a guy about 30 minutes away who would be able to do the fine soldering for me.

Quoted from barakandl:
I also see 74LS02 chip... I don't think you want to be using the LS logic family in this circuit

I'm completely unfamiliar with these chips...what issues might this cause?

Quoted from GRUMPY:
Did you have J19 disconnected when you tested this. Now that the board is out you can retest pin 2 to 3 on the TIPs and compare to the others. You should test ZR-8 for being shorted too

I quadruple checked, and the TIPs do all check out when disconnected. ZR-8, however, is shorted! I think even I might have the skills needed to replace that one, as the leads aren't too close to anything else. I'll give it a shot and report back.

#8 6 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

OP
Quoted from steve8091:
ZR-8, however, is shorted!

This can cause the coil to lock, cut it off of the board and reinstall the board and retest for the locked coil. This maybe your only problem. On F-14 there is no switch input to this solenoid and ZR-8 is not needed for correct operation. Now if you ever wanted to swap this board into another system 11 you should then replace ZR-8.

#9 6 years ago

JMR

pinballplusMN

Pinball Plus Inc.

11y 84,800 2,591 1

I usually add 2.5 amp fuses to divertors on f14. If one locks on it takes a while to burn the 4asb fuse on power supply at which point lots of damage is done.

#10 6 years ago

AMS

barakandl

nvram.weebly.com

12y 132K 10,417

OP
Quoted from steve8091:
I'm completely unfamiliar with these chips...what issues might this cause?

The original part was 7402, the replacement 74LS02 can only sink half the current.

Considering how the original part fails when a solenoid sticks on for a long time, you don't want to push an LS version that hard.

74F02 or 7402 is better part to use.

#11 6 years ago

SAM

steve8091

Pinside member

I'm pleased to announce that simply removing the ZR-8 from the board got my upper diverter working! The slightly bad news is that somehow in the midst of this, I lost the 'take off' sound that plays when you're getting ready to shoot. I have all other sounds and music, but that one no longer plays. That I might just live with.

Quoted from pinballplusMN:
I usually add 2.5 amp fuses to divertors on f14. If one locks on it takes a while to burn the 4asb fuse on power supply at which point lots of damage is done.

Thanks for the tip. I think that I read that somewhere else as well, and I will go ahead and put those in.

Quoted from barakandl:
74F02 or 7402 is better part to use.

Great, thank you. I'll get one of those in ASAP as well.

Thanks again, everyone. I've had this machine for four years, and it's finally playing the way that it should!

#12 6 years ago

DEC

GRUMPY

Pinside member

10y 95,050 8,703

OP
Quoted from steve8091:
I lost the 'take off' sound that plays when you're getting ready to shoot.

Reseat the 4 game roms.

3 months later

#13 5 years ago

MIK

statictrance

Quoted from barakandl:
I had a diverter coil lock on in my F14 and not blow the fuse until things really burned up. I had to replace two logic chips (7402 and one more I can't remember), the 2n4401, and the tip102.

Any chance you remember which other chip you had to replace? I'm in the exact same boat but with the lower diverter and trying to get my GPE order in so I can repair this weekend.

#14 5 years ago

AMS

barakandl

nvram.weebly.com

12y 132K 10,417

Quoted from statictrance:
Any chance you remember which other chip you had to replace? I'm in the exact same boat but with the lower diverter and trying to get my GPE order in so I can repair this weekend.

In my case U50 (7402, 74s02 or 74f02), U56 (7406), Q19 (TIP102), and the Q78 (2N4401) where all bad.

Not sure what failed first to make the coil lock on, but once the coil burned enough to blow the fuse a cascade failure had happened.

#15 5 years ago

CAP

CaptNRetro

CaptNRetro’s Pinball Co

Snellville, GA

6y 36,650 44 5 23

I have an F-14 with roughly the same problem..the upper diverter is not firing..brand new Rottendog MPU, all new coils and diodes..everything else on the machine works perfectly. In switch test nothing is stuck on, coil test fires every solenoid except upper diverter.. if you start a game and play for a while, within a few minutes the 2.5 amp fuse blows in backbox, which stops all solenoids from firing. can not for the life of me figure out what's going on..need help please..thanks!

#16 5 years ago

MIK

statictrance

If the coil is locking on (or melted and causing that fuse pop) there's a good chance that it's damaging your related transistor (believe that's Q77, mine was the lower and is Q79) and possibly further up into the new board. I would be checking the coil itself first, replace, and then verifying your board.

#17 5 years ago

CAP

CaptNRetro

CaptNRetro’s Pinball Co

Snellville, GA

6y 36,650 44 5 23

Quoted from statictrance:
If the coil is locking on (or melted and causing that fuse pop) there's a good chance that it's damaging your related transistor (believe that's Q77, mine was the lower and is Q79) and possibly further up into the new board. I would be checking the coil itself first, replace, and then verifying your board.

All the coils are brand new..the originals were melted..changed the transistor on the Rottendog as well..still nothing

2 weeks later

#18 5 years ago

MIK

statictrance

OK - So I did a little digging on my fried board and wanted to ask a stupid question...

I cut the ZR8 and ZR9 off my board as they aren't needed for F-14 operation - but the upper diverter coil is still locking on. I'd assume the lower one is too - I just haven't replaced it yet.

Also, if I remove power from that one coil to prevent further damage - I have a few coils that fire correctly, but then stay on (upper kicker, jagov, kickback, etc)... I'm guessing that means I have a PIA or two that needs attention (Already replaced the TIP 102). I do have a logic probe and a general idea of how to use it, but haven't used it myself yet. Does anyone have any idea what the high/low readings of the various chips should be before I go poking and prodding around to similar chips on the board (or is my best bet comparing it to another sys-11 board in a different game)?

Here's another - if flippers stay engaged the entire time - I'm assuming that's the engage relay I need to look at... Any reason or concern with just letting them stay engaged outside of gameplay other than it's wrong? (since it's not on location and only powered on in use)

Anyone have any pictures of their special solenoid fuses added? I shouldn't have to worry about kids wrecking this again for awhile, but I want to be prepared for next time.

Thanks ahead of time. Cross-posting with the F14 owner's cllub

#19 5 years ago

PUS

Platypus

Pinside member

8y 42,050 692 3

Terry B has a good tutorial on his pinball restoration site. I find using a logic probe still confusing but when I discovered that one can find the specs of a specific chip and how it's circuited that really helps.

#20 5 years ago

MIK

statictrance