SERVICE MANUAL 3KVA-110V/120V

Table of contents
1. General information .............................................................................................................................................. 3
1.1 Getting start ................................................................................................................................................. 3
1.2 Basic topology introduction ....................................................................................................................... 3
1.3 Inverter family.............................................................................................................................................. 4
1.4 Overview the inverter ................................................................................................................................. 4
1.5 PCB overview.............................................................................................................................................. 5
2. Troubleshooting .................................................................................................................................................... 7
2.1 How to do..................................................................................................................................................... 7
2.2 Check the fault information ....................................................................................................................... 7
2.3 Fault condition............................................................................................................................................. 7
2.4 Test step....................................................................................................................................................... 8
3. Checking and measuring guide .......................................................................................................................... 9
3.1 Check the battery side components ........................................................................................................ 9
3.2 Check the bus side components ............................................................................................................ 16
3.3 Check the buck circuit.............................................................................................................................. 18
3.4 Check the INV full bridge ........................................................................................................................ 20
3.5 Check the PWM SCC board ................................................................................................................... 22
3.6 Check the MPPT SCC board .................................................................................................................. 23
4. Disassembling guide .......................................................................................................................................... 24
4.1 Open the case........................................................................................................................................... 24
4.2 Remove the control board ....................................................................................................................... 25
4.3 Remove the fans. ..................................................................................................................................... 26
4.4 Remove the MPPT board........................................................................................................................ 28
4.5 Remove the main board. ......................................................................................................................... 29
5. Cables connection .............................................................................................................................................. 31

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1. General information
1.1 Getting start
This manual is used as a checking and repairing guide for 3KVA-110V/120V model. Before read this
manual, it’s better to have some electrical or electronic background knowledge. With this guide, you can
fix the inverter by yourself firstly.
There are five main parts of this guide:
General information: This part is the basic information of the inverter; you can start to know the inverter
from this chapter.
Troubleshooting: This part will tell you how to do when you face a problem.
Checking and measuring guide: This part will teach you how to check or repair the inverter by
measuring the critical components.
Assembling guide: This part teaches you how to take the board outside and fix the new one.
Cables connection: This part is a reference for cable connection.

1.2 Basic topology introduction

The topology of the inverter shows as below:

Utility
CNTL board
Control

Inverter
Solar Solar charger Load
Converter

SCC board Main board Parallel

PAR board
(Option)

Battery

Compare with UPS or normal inverter, INVERTER combines a solar charger inside. Solar charger can be
a supplement for battery when there is not grid or for saving energy purpose. And with the solar charger,
the inverter can have more working modes than UPS. For detail information please refer to our user
manual.

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1.3 Inverter family

This service manual includes different models of the inverter, the table as below contains some important
parameters with different models.
These models names are only neutral names; please match the real model name of your inverter to the model
name in the table by comparing the typical characteristics.
Model name Power rating Solar charger Solar charger Off-grid/Hybrid
type number
Inverter with PWM 3KVA 3KVA/2.4KW PWM 1 OFF-grid
Inverter with MPPT 3KVA 3KVA/2.4KW MPPT 1 OFF-grid

1.4 Overview the inverter

PWM 3KVA
is without
MPPT board

MPPT board
Main board

Control board
LCD LED

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1.5 PCB overview

Main board (MPPT):
Control board terminal

Grid
connection
Load
connection

Battery
connection
ISO
ISO TX
TX

Power
Solar supply
connection
To MPPT board BUS soft start
power supply
Main board (PWM):

Control board terminal

Grid
connection
Load
connection

Battery
connection
ISO
ISO TX
TX
PWM SCC
block

Power
Solar supply
connection
BUS soft start
power supply

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Control board:

To Comm
To Parallel To SCC To LCD

To LED

CPU
MPPT SCC board:

Battery connction Solar connection

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2. Troubleshooting
2.1 How to do
When the inverter was faulty, normally there are two main symptoms:
 No display at all;
 Fault code or warning code on the LCD;
When the fault occurred, please help to record the fault information and follow “How to check” of part 2.3
to check the inverter, then feedback the checking result to the service center. It will be very helpful for
solving the problem as soon as possible.

2.2 Check the fault information

Please follow the steps as below to find the issues!
Make sure that you can finish all the steps and feedback us the results. Or we may not be able to
give you the right solution.
Step 1: Test the battery working mode.
Before turning on the inverter, only connect the battery with the inverter which means no solar input and
grid input. Turn on the switch, the LCD will light up and wait for the battery connecting to load.
If the connection is failed, please record the fault code.
Step 2: Test the grid charging mode.
Before turning on the inverter, only connect the utility and battery with the inverter. Without press any
buttons, the LCD will light up. And wait for the utility connecting to battery.
If the connection is failed, please record the fault code.
Step 3: Test the solar charging mode.
Before turning on the inverter, only connect the solar and battery with the inverter. Without press any
buttons, the LCD will light up. And wait for the solar connecting to battery.
If the connection is failed, please record the fault code.

2.3 Fault condition

Note:
When open the top cover, please have a look first, are there any obviously damaged parts?
When take the main board out, please have a look around, are there any obviously damaged
parts?
2.2.1. Not working at all/ No display
Description The inverter couldn’t startup completely.
Possible reason 1. SPS module damaged.
How to check 1. Firstly, please measure the resistor between BAT+ and BAT-. If it is not shorted,
only connect the inverter with battery, and press “ON” button, could the inverter
startup? If not, please check the fan.
2. If the LCD couldn’t light up and fan doesn’t work, please disconnect all the wires
and open the top cover, and then take the main board outside by following part 4.

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How to solve Replace the main board.

2.2.2. 09 fault
Description Bus soft start fails.
Possible reason DC-DC module was damaged.
How to check Check the main board by following “3.1~3.4”;
How to solve Repair the main board or replace it directly.
2.2.3. 56 fault
Description Battery couldn’t be detected.
Possible reason Wire connection or fuse was burnt.
How to check 1. Check the wire connection, the priority of the battery cable;
2. Check the main board by following “3.1”.
How to solve Repair the main board or replace it directly.

2.4 Test step

After replacing all defected components, testing steps can be used to confirm the repair result and the
reliability of the Inverter.

Set up the testing system as below:

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3. Checking and measuring guide

3.1 Check the battery side components
Fuse and capacitors
F3

Parts Attribute Reference values Failure status

F3 Resistor 0 ohm Open

C18/C13/C8

If the capacitors explode as below, they need to be replaced.

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Power devices
DC/DC MOSFET: Q11/Q17/Q20/Q24 & Q38/Q21/Q22/Q12 & Q13/Q18/Q23/Q19 & Q40/Q26/Q25/Q14

Parts Attribute Reference values Failure status

All: Resistor1 GS: 11.7k Short or explosion
GD: 250k
DS: OL
Diode SD: 0.43V
DS: OL
Note1: When you use the multimeter to measure the resistor of the transistor, because of the capacitor in
the circuit, it will cause the changing of the values when you measure the DS and GD. So we recommend
you measure the diode forward voltage of SD, and the resistor of GS. These two values can reflect the
situation of the transistor more correctly.
Note: If one or more of them were damaged, please replace all of them.

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3.1.1. Drivers (This part is only used for repair checking)

Note: Drivers usually need to be checked when users want to repair the boards. Because when power
devices were damaged, the high voltage will rush to driver circuit through the gates of power devices.
The reference of the resistors list as below:
R41/R59/R70/R76/R80/R78/R75/R42/R52/R62/R81/R64/R93/R92/R87/R53

Use multimeter to measure each resistor, find the burnt resistors and replace them; don’t need to replace
them all.
Parts Attribute Reference values Failure status
All: 22ohm Resistor 22 ohm Open or other values
If the resistors need to be replaced, please also check the driver transistors and control IC.

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The Q46and Q48 are 11-300012-00G (TR 2A 50V NPN TO-92)

The Q47and Q49 are 11-300005-00G (TR 2A 50V PNP TO-92NL)

The Q41and Q43 are 11-300012-00G (TR 2A 50V NPN TO-92)

The Q15and Q16 are 11-300005-00G (TR 2A 50V PNP TO-92NL)
Parts Attribute Reference values Failure status
Q46/Q48/Q41/Q43 Resistor BE: 420k Short or explosion
BC: 420k
CE: 30k
Diode BE: 0.6V
BC: 0.6V
CE: 2.3V
Q47/Q49/Q15/Q16 Resistor BE: 420k Short or explosion
BC: 420k
CE: 1.2k
Diode BE: 0.6V
BC: 2.6V
CE: 0.2V

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The Q54and Q56 are 11-400011-00G (TR 2A 50V SOT-89)

The Q55and Q57 are 11-400010-00G (TR 3A 50V SOT-89)

The Q51and Q52 are 11-400011-00G (TR 2A 50V NPN SOT-89)

The Q50and Q53 are 11-400010-00G (TR 3A 50V PNP SOT-89)
Parts Attribute Reference values Failure status
Q54/Q56/Q51/Q52 Resistor BE: 12k Short or explosion
BC: 260k
CE: OL
Diode BE: 0.6V
BC: 0.6V
CE: OL
Q55/Q57/Q50/Q53 Resistor BE: 12k Short or explosion
BC: OL
CE: 277k
Diode BE: 0.6V
BC: OL
CE: 1.09V

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The Q60 and Q61 are 11-420007-00G (MOSFET 5.8A 30V SOT-23)
Parts Attribute Reference values Failure status
Q60/Q61 Resistor GS: 5.637k Short or explosion
GD: 12k
DS: 35k
Diode SD: 0.184V
DS: 1.2V

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Parts Attribute Reference values Failure status

U9 Resistor PIN13 TO PIN12: 22k Short or explosion
PIN11 TO PIN12: 432k
PIN14 TO PIN12: 432k
Note: If you are not sure about these components, we recommend you replacing them all.

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3.2 Check the bus side components

Power devices
DC/DC IGBT: Q27/Q28/Q29/Q30

Parts Attribute Reference values Failure status

Q27/Q28/Q29/Q30 Resistor1 GE: 22 ohm Short or explosion
GC: 181k
CE: 1 Meg
Diode EC: 0.37V
CE: OL
Note1: When you use the multimeter to measure the resistor of the transistor, because of the capacitor in
the circuit, it will cause the changing of the values when you measure the CE and GE. So we recommend
you measure the diode forward voltage of EC, and the resistor of GE. These two values can reflect the
situation of the transistor more correctly.
Note: If one or more of them were damaged, please replace all of them.

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Drivers (This part is only used for repair checking)

Meanwhile, we also need to check the driver tubes of these power tubes.

Parts Attribute Reference values Failure status

R91/R102/R96/R101 Resistor 22 ohm Open or other values
R90/R99/R94/R97 Resistor 0 ohm
D32/D35/D33/D342 Resistor + to -: 240k Short or explosion
- to +: OL
Diode + to -: 0.6V
- to +: OL
Note2: When test the diode; please remove the R90/R99/R94/R97 from the board, or the test result is not
right.

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3.3 Check the buck circuit

Power devices
BUCK MOSFET and Diode: Q32/D13

Parts Attribute Reference values Failure status

Q32 Resistor GS or GE: 23.5k Short or explosion
GD or GC: 273k
DS or CE: 800k
Diode SD or CE: 0.44V
DS or EC: OL
D13 Resistor + to -: 168k
- to +: OL
Diode + to -: 0.36V
- to +: OL

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Drivers (This part is only used for repair checking)

Parts Attribute Reference values Failure status

R125 Resistor 47 ohm Open or other values
R124 Resistor 10 ohm
D38 Resistor + to -: 240k Short or explosion
- to +: OL
Diode + to -: 0.6V
- to +: OL
Note: When test the diode; please remove the R124 from the board, ortherwise the test result is not right.

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3.4 Check the INV full bridge

Power devices
INV IGBT: QA1/QC1/QB2/QD2

Parts Attribute Reference values Failure status

QA1/QC1/QB2/QD2 Resistor GE: 23k Short or explosion
GC: 235k
CE: 900k
Diode EC: 0.4V
CE: OL
Note1: If one or more of them were damaged, please replace all of them.

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Drivers

Parts Attribute Reference values Failure status

R48/R144/R140/R137 Resistor 47 ohm Open or other values
R139/R145/R150/R152
D5/D6/D12/D161 Resistor + to -: 240k Short or explosion
- to +: OL
Diode + to -: 0.6V
- to +: OL

Optocoupler: U1/U2/U3/U4/U12

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Parts Attribute Reference values Failure status

U1/U2/U3/U4/U12 Resistor PIN8 TO PIN5: 2k Short or explosion
PIN7 TO PIN5: 2k

3.5 Check the PWM SCC board

Parts Attribute Reference values Failure status

Q63, Q68, Q73, Q7, Q31 Resistor GS: 433.4k Short or explosion
GD: 705.0k
DS: 774.0k
Diode SD: 0.4V
DS: OL

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3.6 Check the MPPT SCC board

Power devices

Parts Attribute Reference values Failure status

Q2, Q3, Q4, Q10, Q11, Resistor GS: 4.964k Short or explosion
Q13 GD: 37.2k
DS: 260.0k
Diode SD: 0.45V
DS: OL
D8, D49, D48, D47, D24, Resistor + to -: 1.07k Short or explosion
D4 - to +: 1 Meg
Diode + to -: 0.167V
- to +: OL
TVS1, TVS2, TVS3 Resistor 223.3k ohm Short

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4. Disassembling guide
4.1 Open the case
Remove screws on
the top cover

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Open the top cover

carefully, for there are
two cables connected
with LCD display.

4.2 Remove the control board

Remove the cables
on the control board.

Remove the fixing

screws.

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Take out the control

board.

Note: When you put the new control board on the main board, please make sure that the connection is
correct and tighten. Don’t forget to put the screws and cables back.

4.3 Remove the fans.

Remove the fan
paper first.
Use clamp to cut the
bandage.

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Take the plastic

screws out. And then
you can take the fan
paper off.

Remove the screws

of the fans

Remove the fans

cables. And then you
can take the fans out
of the case.

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4.4 Remove the MPPT board.

Note: For PWM model, this step is not available.
Remove the power
cables on the main
board.

Remove the signal

cables away from the
main board.

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Remove the screws

on the MPPT board.

4.5 Remove the main board.

Note: Before replace the main board, please follow 4.2 ~ 4.4, remove the control board, MPPT board, and
fans first.
Remove the power
cables of AC output
and input.
Brown cable is line;
blue cable is neutral.
Do not make the
wrong polarity.

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Remove the screws

on the main board.
And then you can
take the main board
out.

Note: There are nine

screws to fix the main
board.

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5. Cables connection

MPPT PV+

LED 16-500689-XXG
PV-

LCD CN2

Display CN4

LCD

CN2 Panel board CN1

CN16
16-500238-XXG CN5
CN1

CN4 Switch
CN3

CN12

Main board
CN8
16-500758-XXG
16-500757-XXG
Control board

GRID-N
CN5

GRID-L

CN14

CN15
PV-

FAN

PV+

FAN
GRID-L GRID-N

PAR board
CN4

CN3

CN1 16-500243-XXG

COMM board
16-500522-XXG

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