Huntleigh HIGH SENSITIVITY POCKET DOPPLERS Probe Head
Replacement Procedure
Periodic inspection is essential to ensure continued
effective operation.
Equipment Required
Case splitter part number 6AE025 (not required for D920,
D930, FD1 & FD3).
20MHz Oscilloscope (Gould OS300 or equivalent) and x10
probe.
Plastic jawed vice.
DVM on current range
Synthesised signal
generator
Head alignment service kit, part number 6AH072.
Frequency counter
Soldering iron
New case halves, part number 6AE114.
Power supply
The PCB assemblies used in the main unit and probe contain
electrostatic device (ESD). These may be permanently damaged by electrostatic
potentials encountered in routine handling of the assemblies during servicing.
Recommend that all servicing be carried out in a specialised
handling area, (SHA) as defined by CECC00015 to avoid damage to the assemblies.
Preparation - For High
Sensitivity Probes OP2HS, OP3HS, VP4HS, VP5HS, VP8HS, VP10HS, EZ8)
The retractile cable must be disconnected from the control
unit before head replacement can begin.
A spare retractile cable or the retractile cable from the
unit must be disconnected from the control unit before a head replacement can
begin.
Dismantling Procedure - (All
probes except D920, D930, FD1 & FD3)
Align the
case splitter jaws as shown below.
Gently
squeeze the splitter handles together to release the case internal clips.
Remove the
case splitter and separate the case halves from the probe assembly.
Carefully unplug the probe head.
De-solder the
wire(s) from the screen tube and remove tube.
Clamp PCB
lightly in vice along its length avoiding stress to the board.
[The
retractile cable must be disconnected from the main unit before a head
replacement can begin.]
Remove the
probe clips from the probe with a firm leverage.
Discard
clips.
With the
clips removed, take off the Head Assy by disconnecting it from the 4 way
connector on the Probe PCB.
Detach the
case moulding from the end cap and slide case moulding over the probe.
Discard the
case moulding.
De-solder the
wire from the copper screen tube.
Remove the
tube.
Dismantling Procedure - D920,
D930, FD1 & FD3
Note: The
retractile cable must be disconnected from the main unit before a head
replacement can begin.
Remove the
probe clips from the probe with a firm leverage.
Discard
clips.
With the
clips removed, take off the Head Assy by disconnecting it from the 4 way
connector on the Probe PCB.
Detach the
case moulding from the end cap and slide case moulding over the probe.
Discard the
case moulding.
De-solder the
wire from the copper screen tube.
Remove the
tube.
New Head Fitting and Alignment.
Select a new
head of correct frequency, identified as shown below.
The probe
heads are colour coded on the rear of the head as follows:
Connect the
head adaptor PCB (supplied with head alignment service kit) to the probe. Fit
the head to the adaptor PCB as shown.
Connect the
probe in series with the DVM set to measure current and power supply (check that
voltage is 5V +/- 1%) as shown below, using power supply adaptor PCB(D920,
D930) and adaptor cable (OP/VP probe).
Power Supply Wiring
Switch on
power supply.
Connect scope probe to the Transmitter
Terminals (Tx) of the head adaptor PCB and observe Sine wave.
Adjust PR1 to obtain 1.5V +/- 0.5Vpp.
Adjust T1 to
minimise supply current.
Head adaptor PCB
Head Adaptor PCB Ref :
6AH185 To be used with Head Assemblies:
SP-HEAD - VP4HS
SP-HEAD - VP5HS
SP-HEAD - VP8HS
SP-HEAD - VP10HS
SP-HEAD - EZ8HS
SP-HEAD - OP2HSG1
SP-HEAD - OP3HSG1
SP-TDR - OP2HSB1
SP-HEAD - OP2HSB1
SP-TDR - OP3HSB1
SP-HEAD - OP3HSB1
Head Adaptor PCB Ref :
6AH185-B. To be used with Head
Assemblies:
SP-HEAD - OP2HSG2
SP-HEAD - OP3HSG2
SP-TDR - OP2HSB2
SP-HEAD - OP2HSB2
SP-TDR - OP3HSB2
SP-HEAD - OP3HSB2
SP-726222 = SP-726219
SP-726224 = SP-726218
Vascular Probe Head Assemblies
Only [e.g. VP8HS, VP5HS, VP4HS, VP10HS]
Refer to the Head Assembly to determine drive voltage output
for the selected transmitter impedance (see Figure ) Set transmitter voltage
using PR1
Obstetric Probe Head Assemblies
Only [e.g. OP2HS, OP3HS]
Whilst
observing the probe supply current, adjust PR1 so that supply current = 35 mA.
If 35mA
cannot be obtained, set PR1 to maximum current.
Record this
reading on the Device History Record Sheet
along with transmitter impedance and date code.
(e.g. Date
"21st June 1993", Product "OP2", Serial Number
"135",
Transmitter
Head Impedance "24", Drive Voltage "3V", Supply current
“35mA”, Date Code "TAD").
Check that supply current is;
By adjusting
T1, <45mA for VP4, VP5, VP8, VP10, EZ8
Turn off the
power supply and disconnect probe.
