Many boards are replaced unnecessarily. Having worked with these boards since the beginning, at Fadal we would receive boards from service. The typical scenario is the board was replaced in the field, problem solved then the "bad" board was returned to us. We used many sophisticated tests and usually the board was fine. Our standard was then to record the serial number, return to service and if it came back again we would destroy the board.
With the CPU, these actions should be considered before replacing the board.
1) Time to replace the battery?
The memory battery back system was designed to last about 10 years of normal service. The 1" round capacitor (next to the battery) was designed to carry the load over the weekend (off period) then recharge for daily activity during the week, The battery is only used after the capacitor has drained and is under load until power on. A machine being down for an extended time can then be powered up with the parameter and system memory corrupted. This condition will make the CPU board do some unpredictable things, causing one to believe it needs to be replaced.
The first recommend action is to replace the battery. It is a low cost ($8), simple to do and easily available.
Manufacturer: Tadiran Batteries (we wouldn't recommend any other battery type)
Part Number: 667-TL2100T, Battery Size: AA, Voltage: 3.6 VDC, Capacity: 2100 mAh, Lithium Thionyl Chloride - See MOUSER.COM
After installing a the battery you'll need to perform a zeroing of the battery memory, click here for instructions.
2) The second important service to do before replacing any board is to clean the all boards with 100 pin edge connector. You may have seen a serviceman do this with a pencil eraser. A poor connection can cause problems with all boards that plug into the 1060 mother board. In fact, sometimes just removing and replacing a board can repair the problem. A poor connection is one of the main reasons we believed that boards were returned, and then would test just fine.
Cleaning with a pencil eraser is the right idea but the wrong material. The problem is the oils in the eraser can react with the gold plating and oxidize, impacting the conductivity. We recommend using a chemical deoxidizer and protectant called Deoxit for all the boards. It also improves conductivity. They also sell wipes that can be used with the 1060 motherboard to clean in card edge receptacle.
Visit Deoxit products. CAIG Laboratories offers an extensive array of cleaners with details about usage. Be sure to put a sticker on the card cage indicating the date that the card edge connectors have been cleaned.
3) Always check connections! Look closely at the pins, sockets and wire crimps of all related connections. Intermittent failures are common because of bad connections.