System 1 help needed

[humpalot]

Working on my first system 1 game.  A Joker Poker.

Problem I have is that as soon as the power is turned on the "K" target reset solenoid locks on.  The under playfield transistor is correctly wired and has been replaced, the K target reset solenoid coil is also new and correctly wired.  Have tried both repaired original boards and new after market boards with he same result.  I have also replaced the connector between the CPU and driver board. 

The "K" reset solenoid locks on even with all boards disconnected.

The bottom power board reads fine from the transformers, but the voltage is high at the solenoid bridge, is this normal?  I've replaced both bridges and get the same result, I've even tried another bottom power board and it reads exactly the same.

This thing is killing me.

[pinnies4me]

The voltages always seem high on the system 1 boards at the bridge - check the DC voltages at the power board and if they are right then the rest won't be too much of a concern.

[pinnies4me]

Sounds like the ground is locked on, so it must be some sort of short unless something's mis-wired. Have a look at the under playfield mounted transistor and make sure there's no short between the legs (that go through the metal bracket) and the bracket itself.

[humpalot]

Sounds like the ground is locked on, so it must be some sort of short unless something's mis-wired. Have a look at the under playfield mounted transistor and make sure there's no short between the legs (that go through the metal bracket) and the bracket itself.

There is no short between the transistor legs and the metal bracket.

I thought from the start that it might be a ground fault, but even unpicking the harness I can't find anything.

Game works fine if I disable the k target reset solenoid.

[The pinballist formally known as Dean Morgan]

Has to be a short to Ground, trace wiring from the ground side of coil to transistor & check, disconnect from transistor what happens?

[humpalot]

Has to be a short to Ground, trace wiring from the ground side of coil to transistor & check, disconnect from transistor what happens?

If you disconnect the ground from the transistor, then the coil doesn't lock on.

[The pinballist formally known as Dean Morgan]

Did you replace this transistor?

[humpalot]

Did you replace this transistor?

Yes I did twice with 2 new ones

Anyway all sorted now, I've wasted so much time on this only to discover that the brand new transistors that I got are all faulty    Guess they must be made in China even thou they are stamped Mexico 

I had some new MJ2955's lying around and now it's running 100%.

[The pinballist formally known as Dean Morgan]

Did you replace this transistor?

Yes I did twice with 2 new ones

Anyway all sorted now, I've wasted so much time on this only to discover that the brand new transistors that I got are all faulty    Guess they must be made in China even thou they are stamped Mexico 

I had some new MJ2955's lying around and now it's running 100%.

Good News 

[pinnies4me]

Did you replace this transistor?

Yes I did twice with 2 new ones

Anyway all sorted now, I've wasted so much time on this only to discover that the brand new transistors that I got are all faulty    Guess they must be made in China even thou they are stamped Mexico 

I had some new MJ2955's lying around and now it's running 100%.

I had a batch that came from the states recently in pop bumper driver kits that were all faulty too!!

[humpalot]

Did you replace this transistor?

Yes I did twice with 2 new ones

Anyway all sorted now, I've wasted so much time on this only to discover that the brand new transistors that I got are all faulty    Guess they must be made in China even thou they are stamped Mexico 

I had some new MJ2955's lying around and now it's running 100%.

I had a batch that came from the states recently in pop bumper driver kits that were all faulty too!!

Feel your pain.  Mine came from the states as well, the after sales service was good.

[Strangeways]

I've heard of batchs of 5101s and 7180s, but this is getting ridiculous !

Good find though !