Fathom PCBs

This page contains a list of details on what I did during the Fathom Restoration Project to the Printed Circuit Boards (PCBs) in the Backbox and Cabinet.

Along with textual descriptions, I will show a few pictures of the items before and after the procedures.

PCBs (Printed Circuit Boards) in the Backbox

	MPU
	Solenoid Driver Board
	Solenoid Expander Board
	Lamp Driver Board
	Auxiliary Lamp Driver Board
	Squawk and Talk Board
	Rectifier Board

Here's a picture of my PCBs prior to any work being performed. Hey - they're ALL there!!

MPU - AS-2518-35

	Here a picture of the MPU board out of the pin. I've already cut the battery off (you can see it below the board in the picture). I feel lucky, there is very, very little acid damage. I'm getting ready to neutralize the traces of acid on the board with Vinegar, Alcohol and Toothbrush.
	This is a close up of the lower front portion of the MPU. The battery is off the board, but positioned where it was connected. As you can see, there is little to no damage. The only acid on the board is where the battery connections were soldered.
	This is a close up of the lower back portion of the MPU. The battery is off the board, but positioned where it was connected. As you can see, there is little to no damage.
	NOTE: Clay's mod to jump J4-18/19 to Ground Edge still needs to be performed.

Solenoid Driver Board - AS-2518-22

I manually tested the Transistors and Diodes mentioned in Clay's document with the board out of the game. The Capacitor at C23 is not original so it has been replaced at least once. I double checked myself by having the board tested by Chris Munson via his Bally Test Fixture.

	5 TIP-102 Transistors were bad
	1N4004 Diode was bad
	4 330 Ohm Resisters were bad

	2 1.002 Capacitors were bad
	High Voltage Section Tested OK
	Q15 Relay Tested OK
	Solder re-flowed on all connections

The following modifications suggested by Clay were performed:

	Jumper C23 Negative Lead to trace below it
	Jumper between TP1 & TP3

Solenoid Expander Board - AS-2518-66

This board is located under the Playfield. I had to install a light bulb into it.

Lamp Driver Board - AS-2518-23

I manually tested the Transistors mentioned in Clay's document with the board out of the game. I found a few items that were bad.

3 2N5060 SCRs were bad

Auxiliary Lamp Driver Board - AS-2518-52

This board is located on the back side of the "white" board that holds the Score Displays. I tested the components on this board and they were OK. There are 28 MCR106-1 SCRs on the board which are tightly packed together.

Squawk and Talk Sound Board - AS-2518-61a

Below is a summary on the status of my S&T board.

	U1 - 6808 CPU (not 6802) - OK
	U2 - Empty, No ROM - OK
	U3 - Empty, No ROM - OK
	U4 - ROM
	U5 - ROM
	U6 - 6810 RAM - OK since I'm using 6808 in U1
	U7 - 6821 PIA
	U8 - TMS 5200 VSP Speech IC
	U9 - Empty, No TMS6100 VSM "Phrase" ROM - OK, Fathom doesn't use
	U10 - AD558 DAC
	U11 - 6821 PIA
	U12 - Empty, No AY3-8912 PSG - OK
	J2 Connect is Empty (Right, bottom edge)
	?? Connection is Empty ( Left, top edge)
	?? Connection is for Speaker

I'm am not familiar with this board so I'm having someone else who knows what they are doing check all of the capacitors and replace the ones not working. Chris Munson is doing the work. Chris was unable to get it to boot properly and has since returned it.

Clive Jones has a good tech article on Bally's Squawk-and-Talk PCB. The article is on the Pinball News website - www.pinballnews.com.

Rectifier Board - AS-2518-54

I have visually scanned the connections and none of them appear to be burnt. I will take a closer look at them when I redo the cabinet. At that time I will physically remove the transformer and board from the game and test the voltages to verify the Bridge Rectifiers and Resistors are working properly.

I will also fix any cold solder joints and burnt connectors or header pins that show up during the close inspection.

A few pins on the J5 Connector are burnt.

This page was last updated on 10/30/02