Instrument Errors – Drive Board on 402 Unit

Issue: 402 Unit does not work. You may experience an intermittent green light, and/or intermittent fan movement.

Generally this is a failed power transistor on the Drive board.  Typically the drive board needs to be replaced. The board is easy enough that anyone with basic knowledge can change it out. 

Before you receive the new board, you will need to identify if the faulty board is on the left or the right syringe. There are two identical and independent drive boards on each syringe but both circuits are on the same PC board (one drives the valve motor and the other drives the syringe motor). The double drive PC board can however be cut or snapped in half to produce two individual drive boards that can be individually mounted. Gilson supplies both the single drive board and double drive board as spare parts but I would recommend getting the double board this time. 

PROCEDURE FOR IDENTIFYING THE FAULTY DRIVE BOARD ON THE SYRINGE PUMP.

1. Power down the 402 and remove the outside cover. (Held on by 4 screws underneath the unit).
2. Remove the thin plastic ribbon cables (the ones with the pink stripes) from the double drive board on the LEFT syringe (this ribbon cable is common to all drives and provides both power and data to the boards).
3. Power up the unit to see if the fault condition has been eliminated. If the green LED come on and the fan turns normally the both drive circuits on the RIGHT board are OK while one or both circuits on the LEFT board are faulty.
4. If the fault condition remains (flashing green LED and oscillating fan) then it is likely that the LEFT drive board circuits are OK and the RIGHT board contains the fault.
5. If the fault remains after step c. confirm the fault is on the RIGHT syringe board by powering down the units and  replacing the ribbon cables in the LEFT  board while removing them from the RIGHT board.
6. Power on the unit to see if the fault condition has been eliminated. If the green light come on and the FAN turns normally the LEFT drive board circuits are OK and the fault lies with the RIGHT PC board. 

It is very likely that  a power transistor on the drive circuit for either the left or right syringe has blown (short circuited)  as the syringe motor drive draws more current and gets much hotter than the valve drive motor.   

PROCEDURE FOR IDENTIFYING THE A SYRINGE DRIVE OR A VALVE DRIVE FAULT.

1. Once you have identified the faulty board it is necessary to identify if the fault is on the UPPER OR LOWER circuit on the board.
2. Power down the unit and replace the ribbon cable in the lower socket of the faulty board.
3. Power up the unit to see if the fault is eliminated. If the green LED  comes on and the fan turn normally the LOWER drive circuit is ok and the Fault is in the upper board. 
4. If fault remains then the LOWER drive is faulty and it is likely the UPPER drive is OK.
5. Test the UPPER drive by removing the ribbon cable from the LOWER drive and replacing the ribbon cable in the UPPER drive.
6. Power up the unit to see if the fault condition remains. 

Once you have identified the faulty drive put a sticker on it or clearly mark it to indicate that it is faulty BEFORE you remove the board. 

PROCEDURE FOR REPLACING A FAULTY DOUBLE DRIVE BOARD.

1. Unplug the thin ribbon cables from the drive,
2. Remove the syringe and valve from the front of the drive.
3. Remove the two screws that hold the drive in position and remove it completely for the unit. It is a little tricky to remove as the top needs to be pulled out so the face is at an angle of about 20 degrees to vertical while the bottom remains located. It then needs to be lifted slightly to disengage the bottom, pulled forward a little and then lowered slightly before it can be removed without an obstruction. 
4. Unplug the remaining ribbon cables from the drive boards. Each drive has a motor cable and an encoder cable. Note the socket that is used for the encoder cable on each drive as there two identical sockets – one socket is used when the drive is used for the syringe motor and the other is used when the drive is used for the valve motor.
5. Set the dip switches on the new board to the same positions as on the faulty board. (I have attached a diagram of the dip switch settings as a reference). 
6. Install the new board using the two mounting screws 
7. Make sure the board is mounted with the correct orientation as it is possible to get it out by 180 degrees. (If this happened the dip switch setting can be changed on the board rather than removing it).
8. Re-install all the ribbon cables – Power/data, motor and encoder cables. (It is easier to install the thin Power/data cables while the drive is still outside of the unit but the drive will need to be as close to the unit as possible if the cables are to reach).
9. Re-install the drive and secure it in position with the two mounting screws.
10. Power up the unit to make sure there is no longer a fault condition.
11. Test the unit with Gilson Utilities program using the buffered commands “OR” and “OL” to initialize the syringes and the “VRR”, “VRN”, VLR” and “VLN” buffered commands to switch the right and left valve positions. The immediate command “V” can be used to check the valve positions after a command – Depending on the commands sent the status could  be  “NN”, “RR” , NR or “RN” where “N” indicates “Needle” and “R” indicates “Reservoir” . E.g. the status  “NR” would indicate the left valve is set to the needle position while the right valve in in the reservoir position.
12. Finally salvage the good half of the faulty drive board by snapping or cutting the board along the center line. Keep the good half as an in house spare, while discarding the other (faulty side). 

If you want to order the new board from your local Gilson distributors you will need to give them the number on the PC board and make sure they know you want the double board.