By Steve Maull
Over my many years in biomedical engineering and as an instructor teaching equipment service teams about the operation, preventive maintenance and calibration of contrast injectors, I have come to recognize some of the most common phone calls I get about some of the most popular injector models.
Here is my list of common issues and the solutions that are most likely to resolve them.
Bad Head Cable (Stellant or ProVis/Mark V Plus):
The head cable on Stellant and ProVis/Mark V Plus injectors takes a lot of abuse; they get twisted and bent awkwardly countless times a day. The problem is, the head cable is a bundle of wires, and depending on which wire breaks or comes disconnected, that determines the symptom the system starts displaying. However, the telltale signs that a head cable needs replacing are 1) the symptom almost always starts out as intermittent, and 2) the symptom almost always starts out appearing, or disappearing, when the injector head is tilted up or down (whatever wire has come loose in the head cable is making contact in one head position, but breaks contact when the head is tilted in a different direction).
Bad Head Display Board / Switch Card (Stellant or Spectris Solaris):
The display board on the injector head is another relatively high-fail item because it gets contrast spilled on it and it gets pressed on by the operator when filling the syringes, so it takes a little more abuse than most other components on the injector. The symptoms of a head display board in need of replacement often start out as the display segments stop operating or the fill buttons stop moving the piston up and down.
Bad 48 VDC Power Supply (Stellant):
In the main power supply of the Stellant system, there is a 48VDC power supply that is notorious for going bad, (causing error code 3026 or 3028). On that power supply board there are two black wires and two red wires coming into the top of the board. Measure the DC voltage across any black/red pair and you will see it is too low. There is a pot right next to those wires on that power supply board that you can use to adjust the voltage back up to 48 VCD. However, this is just a temporary fix; you still need to replace that 48 VDC board.
Bad Battery (Spectris Solaris):
The symptom will be that the head is not communicating with the display. These batteries are good for several years but at some point it will begin to lose its ability to hold a charge. At first, as soon as they perform an injection, the battery charge indicator immediately drops. Eventually, the battery will just not charge. Solution: Replace your battery every 2-3 years.
Bad Fiber Optic Cable (Spectris Solaris):
If the complaint is that “the injector head is not being recognized by the display” and the battery is not to blame, then this would be the cause. The fiber optic cable is the only means of communication between the injector head and the display. Lying on the floor it can get walked on, rolled on, kicked and yanked. The fiber optic cables have two connectors on each end; one end plugs into the display, the other end plugs into the base of the pedestal. There is a TX (transmit) connector and an RX (receive) connector. If you have disconnected the fiber optic cables and then reconnected them and the system doesn’t work, you probably reinstalled the cables the wrong way; the TX at one end goes into the RX at the other end.
PPI Memory Compare Error (ProVis/Mark V Plus):
PPI stands for Pre-Programmed Injection. This board stores the protocols the operators keep in the system’s memory as well as the injector’s configuration setup. This board is powered by a 3-volt battery that lasts about 10 years. When this battery gets below 2.6 volts, you start getting a “PPI Memory Compare” error. Rather than replace the entire board for about $1000 simply de-solder the old battery and solder the replacement battery (roughly $10) in its place.
“Injector Not Injecting” (ProVis/Mark V Plus): The ProVis/Mark V Plus system can inject at three different flow rate settings: ml/sec, ml/min and ml/hour. 99.999999% of the time they use ml/sec but it is relatively simple to “accidentally” switch the flow rate mode to ml/min without realizing it. That flow rate is so slow that it can seem like the injector is not injecting at all. They press the start switch and nothing appears to be happening because the injection is so slow (if an error message came up, that would be a different issue). Obvious solution: ask them to make sure they are still shooting in ml/sec.