If you replace the driver transistor, replace the pre-driver above it too.

If one goes, the other usually is stressed and soon goes too.

Replaced driver transistor at Q77. Tests good now. Turned game on, right kicker didn't lock on so thought everything was good. First time the switch for the right kicker went on it kicked on and stayed on. Turned game off. Transistor still tests good. Not sure what to look at now
The pre driver tests good too, didn't have a spare one to replace it

Just to entertain me, take the ball out and go into switch test mode.

When you turn the game on now, does the coil lock after about 1/2 a second?

Coil locks on now as soon as I turn the game on regardless. Not sure what changed

If a transistor is shorted, the kicker would lock on Immediately...there would be no waiting period for the switch to be activated. - as in what you just experienced. Your leaf switches for the slings are shorting and this is what is causing your lock on condition.

So I would need new leaf switches?

Unhook one wire to the stuck coil.

Take the ball out

Go into Switch Test.

Ok will try tomorrow morning

I believe that the only active coil in attract mode is the saucer kick out (so that if the game lost power, the ball could be returned to the trough upon power-up).

I don't think that the slingshots would respond to the switches unless a game has started.

I could be wrong, somebody check my math....

Not necessarily. One thing to look at is to make sure that at rest the leaf switches open with a sufficient gap, and check them with a multimeter to make sure they are not shorting.

I verified your math on our Comet, the slings are inactive and the saucer kick out (funhouse) is the only one that is active in attract mode.

Leaf switches have the same gap as the left kicker and are not shorting.
Switch test shows it is working.
In attract mode there is no power running to the left kicker, but there is 28 volts running to the right one. Going to replace the IC chip at U7 and see if that helps. Something is trying to turn the right kicker on at all times. Not going to be around to test anything else for a few days and then the IC chip will be here so hopefully that will fix it, if not it's back to the drawing board

Sounds like you are shotgunning and just fixing by luck rather than troubleshooting. You can use an oscilloscope, logic probe or even a DMM to test signal flow in and out of that IC when in solenoid test mode, to actually determine if it is suspect. The pulse train is shown in the diagram below (which is actually a system 11, but similar)

There should be power here anytime the power switch is turned on. All solenoid power comes directly from the power supply. Does the left kicker even work? The 7402 IC gates (U6,U7) are what is turned on with the flipper enable signal at game start or test mode - that gate will then allow the switches to create a ground path to the solenoid. Keep in mind that power is not turned on and off to operate solenoids - GROUND is turned on and off.

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Yes the left kicker works perfectly. I guess that's what I don't get. When I measure at the left kicker in attract mode I'm not getting 28 volts but I am on the right.
Basically I ran out of time to do further testing and am out of town for almost a week. For $3 I figured why not give it a try. I didn't want to be gone then come home find out it's what needs replacing and then have to wait another week for the parts to come in.
Downtime for repairs is a bummer when you only have 2 machines. We play every night too. Guess it just means I need to buy more pins!!

The pre-driver 4401 could have been stressed (even if it tested good) and the first trip of the slingshot switch killed it all the way, locking the coil on.

This is a very common 'I fixed it, now it's dead again' happening.

If you like shotgunning, then this time replace the trans AND the pre-trans.

(if you own pins, keep a stock of TIP102 (more heavy duty than the TIP122) and 2n4401 transistors, and coil diodes always in your tool kit)

I joined the club myself this weekend, courtesy of a fellow Pinsider a couple of hours away from me. Game works great, but has some cosmetic issues I’ll be working my way through. I’ve been reading this thread for the last bit, and it’s really interesting.

Hmmmm... I’ve only had to change out a handful myself, but I always made a point of replacing a transistor with the exact same. I took a quick look online but didn’t see any sort of interchange or compatibility table.

What Vid says... Upgrading TIP122's to TIP102's is a pinball basic rule.

Oh, I wasn’t questioning it. Just asking if there was a conversion table. The tips used in Dara east games are comparatively expensive.

It's the same part, just with a higher amperage rating 5A vs 8A.

It costs 2 cents more, so better to get the heavy duty component.

You should read your Data East repair bible again:

TIP122: used at Q39-Q46 (multiplexed), Q8-Q13 (special coils), Q23-Q30 (constant power), Q72-Q79 (lamp matrix row returns) on the CPU board. When replacing a TIP122, always replace a TIP122 with a TIP102 instead. The TIP102 is a more robust version of the TIP122. Equivalent transistors for TIP122 = NTE261; TIP102 = NTE2343.

http://techniek.flipperwinkel.nl/desega/index2.htm#trans

That's what I did to mine. Translucent led different color caps. Looks awesome with freeplays translucent colored ramps!

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I may be able to get a scan. Let me see what I can do.

IC chip came in. Didn't change anything. Back to testing.

Could somebody tell me where this goes? When I stripped most of the playfield to clean I was left with this and can't remember where it goes. Thanks!

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It goes above the shooting gallery on the right side. I'll post a pic in a minute.

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Aghh I take it that it's supposed to support the ramp. Never noticed a issue without it but I'll throw it on. Weird that it blocks the plastic though from view from above.
Thanks for the help!

No, it doesn't support or touch the ramp. It's to keep flying balls from getting stuck up between the plastic and the ramp.

Oh ok that's good to know. In my case I may just throw it in the cabinet since my machine is just for home use. I did a complete parallel flipper conversion kit install from Pinballlife and even with such haven't had any issues with the ball flying around in that area or getting stuck.

The balls will get stuck there, next time you wax the game, just slip that guard back in place.

Also, it's the perfect place to slip a LED lamp strip under, to light up the dark center of the playfield.

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Alright I'll reinstall it lol good idea about the light. I actually have a few of those lights onhand that I bought for the rear of Jurassic Park that I haven't got to.

Vid thanks for the great right up on the conversion from serial to parallel flippers. I ordered the kit from pinball life, put on the capacitors, and installed them. Very quick and easy. The old eos switches were so pitted and burnt up I'm not sure how they even worked!

Getting ready to start @PinDeLaPin's playfield project. Here are a few 'before's'...(look familiar @Malenko??)

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I knew that was my old one before I even saw my name lol. You do good work, and it makes me happy knowing my old PF is going to be restored to improve another comet

Funny! My current one isnt nearly in as bad shape as that, just wanted one to look new again. New ramps from Mark Freeplay40 are sitting on a shelf waiting to be installed on my new to me playfield. Ok Scott keep those status pics coming.

Dabble in playfield necromancy much?

Replaced transistor again. Game played perfect for about 30 to 40 seconds. The right slingshot worked fine when the ball hit, no problems at all. Thought everything was fixed and then there is a kind of building hum sound and the right slingshot locked on again! Bummer! Transistor tests fine right now. What else should I be testing?

Initial paint removal on PF. Inserts are all in very good shape and level. Couple of spots in pics where we will have to do a little filling where ball drops damaged the wood under the paint. Also will fill in some of the major chipped out areas where posts have been moved around over time prior to a coat of clear and the overlay work.

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Another post in the locked on right slingshot saga...
After going through everything again I decided to isolate the leaf switches. Disconnected the orange/red wire to the switches and now I can turn the game on without it locking on. Thought ok it must be a problem with the switches. Took them out of the slings and it looks like it has been worked on before. One of the wires is not soldered on good and has a good amount sticking out. Thought maybe it was touching something and shorted. Trimmed the wire and resoldered. Now with the switches hanging down everything is fine. I can even activate the sling by manually touching them together. Put the switches back, made sure they were no touching and none of the wires were touching. Everything works!! Put it all back together and started a 2 player game with my Dad. I played the first ball for 2 minutes no problem, ball comes off the slings just like it should. On his turn the ball hit the right sling once and the GI lights dimmed, something that was happening a few months ago, and then it hit again and locked on. Went back though and tried everything I did before and no luck. Locked on no matter what. Really stumped and frustrated.

Is it possible that the sling arm itself is pinching a wire or rattling something nearby that causes a short? Or maybe there's a short elsewhere that happens upon vibration when the sling triggers? I'd look at every little thing in that quadrant of the playfield. Can you make it happen by thumping the playfield with a closed fist?

Looking good Scott, you are making good progress on it. With this whole new playfield it may just inspire me to overhaul the cabinet and re-stencil as well.

Mine needs some serious cabinet work as well. Someone instead of fixing one of the rear corners correctly went through the trouble to get a corner metal plate welded and mounted in the game when it probably would have taken 15 minutes and some wood glue and a lot less know how then getting that butt ugly plate made up! Otherwise I’m pretty happy with the games condition and I love the game! Comet is a keeper for sure.

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Sling arm is not pinching anything. Looking around the area I don't see anything out of place. Right now I actually can't get it to NOT lock on, it happens the second you turn the machine on. No idea why it worked for 2 minutes then stopped. Diode and transistor both test fine. IC chip is brand new. Pre driver tests fine.
Maybe something to do with the relay?

So the coil is locking on BEFORE the MPU boots?

It locks before the screams come from the speaker?

Yes

Went over Comet and tried some stuff for the locked on right sling today and still no luck. I'm going to create a separate thread for it so I don't keep clogging up the club thread.

If anyone is interested I had bought the last overlay from user boydsc331 and drscottsmith had just started to refurbish an old playfield for me. If you aren't familiar with drscottsmith go back and read this thread he does beautiful work with these overlays. Due to some extenuating circumstances that came out of the blue a few days ago I will no longer need the playfield and wanted to pass this opportunity on to a fellow pinsider. Scott has already began the process and is almost done prepping the old playfield for the overlay. If somebody is looking for a new playfield now is your chance to get one and not have to wait very long to get one pm me for details.

To close out my problem big thanks to vid. He reccomended changing the transistor, pre driver and diode all at once and sure enough problem solved!
Apparently changing them one at a time would not work.

Congrats! Nothing worse than a pesky problem that keeps you from playing your game. If you are ever gonna listen to anyone he is the guy to listen to. I've spent hours reading a bunch of his how to's.

Thanks! We had a ton of fun in the family arcade tonight. 4 back to back games with my 5 year old daughter and my wife playing by herself later hit the million shot for the 2nd or third time since we have owned it and got her best score ever.

Congrats on the repair!

With your cherry completely busted, you are now officially a pin-tech!

I installed a set of System 9 Pinscore displays in my Comet and found that they don't display the commas. Marco Specialities thought that the issue was probably the driver board and promptly sent me a new one, but it didn't solve the issue. I put my old plasma display driver board back in temporarily with one of the old displays to make sure that it wasn't a CPU or ribbon problem. The old display worked fine. Has anyone else run into this problem or have insights as to what might be going on?