Mindray BS-200 User manual

Solution for Liquid Level Detect error of BS200

Solution for Liquid Level Detect error of BS200

I. General

When aspirating samples/reagents and dispensing sample in reaction disc, the
BS-200 chemistry analyzer requires the probe to dip into the liquid for a specific depth
(3mm below the liquid level), so as to avoid carryover that has impacts on test results, and
to avoid air aspiration when the reagent/sample is insufficient. Also when washing the
probe in washing pool, probe also need to stay at a special depth to wash the inner part
and outer part.

II. Composition of Level Detection System

The Level Detection System consists of:

1) Sample/reagent probe,

2) Liquid level detection board,

3) Electric wire from liquid level detection board to probe connection board,

4) Electric wire from liquid level detection board to main board,

5) Main board.

 Liquid Level Detect board

The level detection board requires the 5V and 9V voltages. The 9V voltage is the
working voltage of the phase-locked loop, and 5V is the working voltage of other
components on this board. The main control board supplies this board with a 12V voltage,
which is converted into the 5V and 9V voltages as required.

:

 Main board

Solution for Liquid Level Detect error of BS200

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 Sample/reagent Probe (Dual-tube)

Inner probe tube

内针管

Inner insulation layer

内绝缘层

Outer probe tube

外针管

Outer insulation laye

外绝缘层

III. Level Detection process

When the sample/reagent probe touches the sample/reagent level, there will be a

change in the capacitance between the two tubes inside the probe. As the capacitance

Solution for Liquid Level Detect error of BS200

changes, the phase changes. The phase discriminator then outputs a voltage variation,
which will be filtered by a low-pass filter. After that, a band-pass filter takes the variation
and reshapes it to pulse signals, which are finally transmitted to the MCU of the main
control board.

Solution for Liquid Level Detect error of BS200

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IV. Check procedure (please enlarger the font to see clearly)

LLD error

1) Can’t detect
liquid level in
reaction disc

When aspirate reagent, probe detect reagent level by mistake, so probe aspirates air which leads

to no reagent in reaction disc, when add sample, probe can’t detect liquid level at special height.

Cause: see 3) Detect liquid level by mistake

When aspirate reagent, probe aspirates insufficient reagent and add to reaction disc, when add

sample, probe can’t detect liquid level at special height in reaction disc.

Cause: syringe not fixed, bubble in reagent disc, reagent leakage

s 2) LLD function paralysis

No reagent in reaction disc

Insufficient reagent in reaction disc

LLD function paralysis

When probe touches liquid level, the LLD voltage changes normally, and LED1 is on for about 2

seconds, but still there is an error message said: can’t detect liquid level

Cause: wire disconnect or bro ken, c onnec tor f aulty. In this cas e, u sually w e can’ t detec t th e v olt ag e

change in main board.

Solution: reconnect wire on LLD board and on main board,

LLD signal transmit failure

When probe touches liquid level, the conversion of LLD voltage changes normally, and LED1 is on fo
about 2 seconds, also we can measure the v olt age change i n J35, but still ther e is a LLD e rror message
Shown in the screen.

LLD signal tackle error (by main board)

2) LLD function
paralysis

3) Detect liquid
level by mistake

Probe is ok, but LED on LLD board is always on, or even
probe touches the liquid level, LED still off, that may be

Produce LLD
signal
Failure

In this condition, there is no error message at all, but we can know from reaction curve that no
sample/reagent be added
Possible problem: Probe broken, connection wire not good, signal influence (main board or LLD
board not work normally).
Solution: reference check procedure and change relation parts

This condition only occurs when add sample, (when add reagent, the probe doesn’t detec
liquid level) although there is no error message at all, but we can get some information from
reaction curve, also, there will be some leakage from the needlepoint when probe moves from
reaction disc to washing pool.
Possible problem: probe isn’t in the center of cuvette, bubble in reaction cuvette

something wrong with LLD board, also we can check the
voltage on LLD board to confirm.
Solution: change the LLD board, adjust LLD voltage

Inner part and outer part depart, distort, and so on
Solution: change probe

Detect liquid level by mistake in sample/reagent disc

Detect liquid level by mistake in reaction disc

LLD board problem

Probe problem

Solution for Liquid Level Detect error of BS200

V. Convert defective parts

(a) LLD voltage adjustment

Location of the liquid level detect board:

LED1

Liquid Level Detect board:

FRONT VIEW 1

TP2

What we need to do is like below:

1) Detach the cover of probe arm.

J66

VR1

TP4（ground）