The Bardscan IIs is a portable 2D mechanical sector B-mode ultrasound intended for measuring bladder volume.
The device was originally designed by Mediwatch PLC and released as the Mediwatch Portascan, later upgraded to the Portascan+:
In 2008, Bard released a relabeled version as the Bardscan II. GE also released a relabeled version as the GE Portascan.
All three devices appear to share the same core design:
- battery-powered (with AC option)
- dual-frequency 3.5 / 5.0 MHz mechanical sector abdominal probe
- digital 512 × 512 × 8-bit scan converter
- ~8" color TFT touchscreen LCD (640x480)
- Windows environment
The differences between the Bardscan II and the Bardscan IIs are not clear. This video shows a teardown and repair of a Bardscan II, with the main PCB labelled "Mediwatch Portascan 2 Issue 2". My Bardscan IIs is labeled "Mediwatch Portascan OMAP Issue 6", and has a considerably simpler layout with much fewer components.
The main PCB, labeled "Mediwatch Portascan OMAP Issue 6":
The touchscreen display is an AU Optronics G084SN05-V9:
The thermal printer PCB, labeled "Mediwatch Portascan+ Printer":
The thermal printer is a Fujitsu FTP-628MCL054:
The ultrasound probe connects via a 16-pin LEMO PFG.2B connector:
Which terminates at the PCB:
My ultrasound probe was not activating during a scan. The motor was not running and no image was being produced. The problem persisted on a second ultrasound probe.
An x-ray of the probes did not reveal any clear mechanical problem:
Two chips were overheating:
| Ref | Part | Function |
|---|---|---|
| U30 | LT3481 step-down switching regulator | Generates a low voltage rail used for the pulser |
| Q5 | ZXMN10A08E6TA N-Channel MOSFET N-CH 100V 1.5A | Driven by U8, drain goes to D7, acts as high-voltage enable when a probe is present |
Testing Q5 revealed it was blown. Replacing Q5 eliminated the overheating problem, but the probes were still not activating.
After a lot of oscilloscope and multimeter probing, the rough layout of the PCB becomes clear:
The left-hand block handles power conversion and generates the +/- 100V rails used by the pulser. The right-hand block handles the probe TX/RX.
After investigation, more parts needed replacing:
| Ref | Part | Function |
|---|---|---|
| U7 | TC6320TG-G high-voltage complementary MOSFET pair (1x N channel, 1x P-channel) | Ultrasound output switch |
| U8 | LM5112 MOSFET | High-voltage enable gate |
| D5 and D6 | Schottky diode | Shapes the high-voltage rail and protects the pulser |
After replacement, signals were checked higher up the signal path:
| Ref | Part | Function |
|---|---|---|
| U6 | MD1213 high-speed dual MOSFET driver | High-voltage gate driver for U7 |
The important signals (INA, INB, OUTA, OUTB, OE) looked good, everything was put back together, and the probes were working again.