Innomed Medical
Heart Screen 60G-80G-L
Service manual
2014.01.09 10/84
D-5450-1-B_HS60G80GL_SM_ENG.doc
5.2
HS80G-L Main board ECG amplifier unit
(D-1127B_HS80G-L_Main_Board_Electrical_Sch)
5.2.1 Main functions as grouped by the connection diagram:
1/9. ECG input
This is where the device’s ECG input circuits and the main amplifier levels with some of the error handling
circuits. Further, this is where the multiplexer (U28) selecting the channel for the AD converter is located.
2/9. Overload Circuits
The pace checking and latch-up checking circuit input, signal preparation levels.
3/9. Filter
Contains the filter circuits with the connecting and blocking circuits.
4/9. ECG AD
This is where 13-bit AD converter (AD1), the reference-voltage creating circuit (OP2), the amplifier controller
(U20) and the processor isolating circuits (OP1-OP4-Q2) are located.
The two monostable circuits in U10 perform the combined latch-up / pace signal shape forming.
The two monostable circuits in U23 extract the auxiliary signals which belong to the ECG data pockets (Clock,
Data ready/DMA request).
5/9. Isolated power supply
Contains the isolated switching power supply, which, besides the basic voltage, creates the negative voltage
needed for the LCD contrast.
