Can you post a picture of the transformer module?
Would be interesting to see where the spinning motor power wires come from the transformer especially their wire colors.

Some solenoid expander boards (SEB) have the solenoid 43V connected to one of the switch legs on the relay with a wire link. Essentially this link wire connects pin 4 to pin 9 on the plugin connector. This causes havoc with some games when the link is installed when it shouldn't be.

Your original SEB shows that wire link is cut which should be right (you can see the cut jumper link between the diode and the relay on your old board).

Does your replacement SEB have any jumpers links?
Where the yellow-white and yellow-red wires for the spinning disk motor connect at pins 4 and 5 on the SEB, do you measure any continuity to other pins on the connector (other than potentially pin 7, there should be none).

The power wires for the spinning motor come off the transformer which we don't have full view of in that picture. I can see a yellow-red wire top right corner but can't see where they come from.
Can you post a pic showing less of the rectifier board and more of the transformer?

Is there any instructions with this SEB on how to jumper it?

If you measure continuity between pin 4 and pin 9 on the connector then you need to cut that JMP 1 jumper. It's connecting solenoid DC power to the spinning disk motor solenoid AC power which is wrong for this game.

See the previous post about the SEB.

In your second picture there is a floating two pin connector with yellow-black and yellow-red wires on one side, and yellow-red and thick red wires on the other side. That connects the transformer to the playfield spinning motor.
The thick red wire has a black cylindrical thing on it which actually contains the fuse for the spinning motor.

Hi @BigAl56, the online Fireball Classic schematics are missing the SEB schematic - not sure if they're in the real paper schematics.

What I can tell from the pictures above:
The fused motor wire connects to the orange wire on the transformer which is solenoid 43 volts AC. This leads directly to the spinning disk motor as the yellow-black wire.
The yellow-red wire connects to the other transformer solenoid 43 volts AC wire which is green.
This yellow-red wire goes to the playfield at pin 4 of the solenoid expander which is the relays common switch arm.
Pin 5 of the solenoid expander is the relays N.O switch contact and connects to the motor as a yellow-white wire.
Pin 9 on the solenoid expander is 43 volts DC used to power the relay.

If pin 4 is jumpered to pin 9 on the SEB then this is shorting the 43 volts DC (after the bridge rectifier) to the 43 volts AC (before the bridge rectifier).
In my mind, that jumper on the SEB needs to be removed so the relay switch is isolated from the DC side of solenoid power.
The picture of the original SEB above shows that jumper is cut.

Have you checked this ^^^ with the SEB installed?

Below is the solenoid expander schematics on Fathom and Centaur.
When the relay is Off, pin 4 is switched to pin 7.
When the relay is On, pin 4 is switched to pin 5.

The Fathom setup shows the purpose of the jumper is to connect pin 4 to pin 9 (which is 43V DC solenoid power). This setup switches solenoid 43VDC power between two banks of solenoids on the playfield.

You need to cut that jumper on the SEB for Fireball Classic. It's shorting 43VAC coming in on pin 4 to 43VDC which is coming in on pin 9 and is causing the playfield 43VDC solenoid fuse to blow.

Scroll down to @barakandl's solenoid expander board on this link - you can see it specifically states to cut the jumper for Fireball Classic.
https://nvram.weebly.com/new-pcbs.html

To check the continuity previously mentioned:
Machine OFF.
Set your meter to low ohms range.
Touch both meter leads together - the multi-meter should show near zero ohms indicating continuity.
Put one meter lead on pin 4.
The other meter lead on pin 7 should make the meter indicate near zero ohms for continuity.
Move that meter lead from pin 7 to pin 9 and you should again see the meter indicate near zero ohms (assuming you haven't cut the jumper yet).

SEB_Fathom.gif
SEB_Centaur.gif

Cool.
And there were no instructions that came with the new solenoid expander board explaining the jumper?