I would check all the connectors that are part of the row circuitry. Wiggle them while the game is on and see if the lamps start working/not working. With the game off, tug lightly on the row 2 wire where it goes into the connector and see if it's loose.

Based on this you'll have to work pretty quickly, but I would check the input and output on the interconnect board with a DMM or logic probe (better choice). That will identify if it's a board problem.

Try some freeze-spray (canned air upside down) across the same connectors as well as possibly the transistors and other components coming from the connectors on the MPU and see if that isolates where the problem is, since it seems like it's thermal failing component. I would bet there is a bad solder joint on the MPU or something?

The online manual is extremely hard to read, but I think I've got the correct test points. Row 2 will be a red/blk wire so you can confirm I've got the correct pin on the connector.

Meter set to DC (20 volt range or whatever is close), black lead on ground and red lead on each of the following test points (one at a time): J3-17, J14-2 and J15-2. After you're setup to take the first reading turn on the game and see what reading you get and if it changes after 15-30 seconds when row 2 starts working. Don't worry about the reading prior to the game booting up since it will change during that period.

Yes, it can be a little difficult to hit the right spot, but you'll get the hang of it after a few tries.

Where did you take the reading? As I explained earlier you need to check in the 3 places I noted while the inserts are not working.

Sounds like you've got a broken wire between the interconnect board and the playfield. With the game off check continuity from any of those connector points I gave you to one of the switches in that row (red-blk wire). Do this when the machine is cold and hopefully the problem will exist at that time (since it seems to go away after the game is on for a while).

Just to confirm, none of the lights in row 2 work?

I'd replace the transistor, if that doesn't do it then the first IC upstream from it.

LTG : )™

Yes install a TIP102

Makes sense.

Q81 was replaced and problem still exists

Does anyone know acceptable replacement for IC7406 which is next upstream one and dont have one of those

There is no substitute for a 7406, just different manufacturers.

https://www.greatplainselectronics.com/proddetail.asp?prod=7406

Ed has them. Don't know if rat shack does.

LTG : )™

Something is warming up and then working. component, trace, solder joint. These are the issues that can drive you nuts. Easy fix, near impossible to find.

LTG : )™

Buy a logic probe and then you can accurately walk through the circuit. The problem is with it being intermittent it's a tough problem to nail down.

It's often hard to explain everything to check when helping someone out since there are so many things that a seasoned tech does without even thinking about. Pushing on components is one of those things. I do it without even thinking about it. Also visual inspections will catch a ton of problems, but if you don't have the experience then you wouldn't know what to look for.

A good way to look at it is to use all of your senses. Sometimes the sound of a coil firing, the smell or feel of an overheated component, the look of a solder joint will get you there faster than pulling out your meter.

Intermittent problems are a pain no matter how much experience you have. Overall you did pretty good, and learned a few lessons along the way.

Last but not least--tools. Lamp and switch matrix problems are a lot easier when you have a logic probe (at least in my opinion, some will disagree).

Pretty much the same path you took. Intermittent problems can be tough to find and easy to fix.

LTG : )

Shotgunning a repair is never good.

You waste parts. Yeah, they may be inexpensive, but it's worse than that.

You're soldering on a board unnecessarily. Heat is the enemy of the board. Even if you're good, and have experience, you can make a mistake, burn a trace off the board, pull a plated through hole.

Plus, what if you did that in the process of replacing the transistor, predriver and 7406? Now, you've got *20* solder points that could be messed up - some on both sides of the board - and some going multiple places! So, now you're messing with your schematic, trying to figure out what plated through hole you pulled. Better hope you didn't change the PIA - that's *another* 40 solder points. See where I'm going?

The way I troubleshoot these things - buy a logic probe. They are cheap. Get the schematic out, and look at a *working* row. Look at the state of the components in the working row. Compare Q81 to the same part in a working row. Does it behave the same? If so, you can be sure with a fair degree of likelihood that the problem is *after* Q81. If Q81 doesn't behave like another nearby row, go back the other direction on the schematic and work your way back to the PIA. Compare the PIA output tied to the non-working row to the PIA output tied to a working row.

At first, you're going to say, this takes more time than just shotgunning. Well, it may at first, because you're learning how to use your logic probe, and learning how the circuit works.

But, when you do this next time... or the time after that, you'll be ready.

Another good investment? Leon's test ROM and a used computer power supply. Wire the ground, +5 and +12 to the CPU board, throw the test ROM in U27, and it'll pulse the PIAs up and down in rhythm. It'll do all the PIAs. Then, you can grab your logic probe, and see where the signal stops *on your workbench*. This is helpful, as that allows you to have good light and easy access.

This is an ATX power supply from a 10+ year old computer, modified to provide +5, +12 and -12 0 I use it to bench test boards of all varieties. Plugs allow me to have a pigtail for different styles of boards, as different mfg/era require different pinouts.

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This is my WMS Factory test fixture for Sys 9 and 11. Works great to allow me to probe around with a logic probe and trace things out. After years of digging around in dark backboxes with logic probes, I finally located one of these. Very helpful tool - but for the casual pinball enthusiast, completely unneccesary.

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