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Programmes After Market Services NHE­8/9 Series Transceivers

Disassembly & Troubleshooting

issue 2 11/97

NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

CONTENTS
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Module Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phone is totally dead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flash programming doesn`t work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power doesn`t stay on or the phone is jammed . . . . . . . . . . . . . . . . . . . . Display information: Contact service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phone doesn`t register (no serv) or doesn`t make a call . . . . . . . . . . . . SIM Card is out of order (insert SIM card or card rejected) . . . . . . . . . . Audio fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Charging fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UIF Module troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UIF­ connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Microphone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Earpiece . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Buzzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keyboard and display LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4 4 4 5 6 9 11 12 14 17 19 20 20 20 20 20 20 21

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PAMS Technical Documentation

NHE­8/9 Disassembly & Troubleshooting

Disassembly
1
Remove battery

2
Remove 6 screws from the chassis

4
Remove the A cover

3
Remove 3 screws from the shield

5
Remove the shield

6 Re­assemble in reverse order

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NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

Troubleshooting
General
The purpose is to define the faulty module block, and then to locate the faulty component. The trouble shooting diagram has been planned so that the fault, whatever it is, can be found by as simple measurements as possible. The flow charts give you the overview of the blocks. The purpose is that you proceed through the flow diagram so that, if your answer is YES for the asked question, go straight to the next level, but if your answer is NO, you have to go the sub­branch. Required servicing equipment: ­ PC for Service Software ­ Power supply (2.0 A) ­ Digital multimeter ­ Oscilloscope ­ Spectrum analyzer ­ Signal generator ­ RF cables ­ Modular cable ­ RS232/MBUS adapter ­ HP8922H or equivalent ­ RF measuring chassis

System Module Troubleshooting
The following hints should facilitate finding the cause of the problem when the circuitry seems to be faulty. This trouble shooting guide is divided into the following sections. 1. Phone is totally dead 2. Flash programming doesn`t work 3. Power doesn`t stay on or the phone is jammed 4. Display information: Contact Service 5. Phone doesn`t register to the network or phone doesn`t make a call. 6. Plug in SIM card is out of order (insert SIM card or card rejected). 7. Audio fault. The first thing to do is carry out a thorough visual check of the module. Ensure in particular that: a) there is not any mechanical damage b) soldered joints are OK

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NHE­8/9 Disassembly & Troubleshooting

Phone is totally dead
Trouble shooting diagram for this fault is represented in figure below Check at first that the battery back is OK and it is not empty. This kind of fault has been limited around the system connector (X100) and the PSCLD (N300).

If the phone is totally dead, check that

Voltage level at PSCLD (N300) pin 25 is same as VBAT
YES

NO

PSCLD N300 pins 5,21,37 voltage level is same as VBAT
NO

YES

Connect pins 18, 22 and 31 together (X101) and measure that voltage level at pin 25 (N300)drop to zero.

Rise up PSCLD pin 25. If the DC voltage is still missing change N300

Check coils L311 + L301 and the sol­ dered joints of the connector X100

NO

The voltage level at pin 25 (N300) is zero

YES

Check soldered joints of X100 and PCB wires between X100 and N300

NO

PSCLD (N300) switches power on so the regulated voltages VL, VA and VSL are 3.16V

YES

Check that capacitors C329, C330, C310 and C311 are soldered. Check also soldered joints of N300. If these things are correct, change N300

Check the UI board and the PWR button.

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NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

Flash programming doesn`t work
In error cases, the flash prommer can give some information about a fault. The fault information messages could be: ­ MCU doesn`t boot ­ MCU flash Vpp error ­ Serial data line failure ­ Serial clock line failure ­ External RAM fault ­ Algorithm file or alias ID don`t find In cases that the the flash programming doesn`t succeed, there is a possibility to test the interface between the ASIC and the MCU. This test is useful to do, when the fault information is: MCU doesn`t boot or Serial clock line failure. The test procedure is following: 1. Connect a short circuit wire between Asic pins 137 and gnd. 2. Switch power on. 3. If the reset line of the MCU rises up, the interface is OK. Otherwise the reset line stays low.
Note: this test can only find short circuits, not open pins.

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NHE­8/9 Disassembly & Troubleshooting

Flash programming doesn`t work

Output voltages of PSCLD (N300) are 3.16 V ( VL, VA, VSL )
YES

NO

Check the soldered joints of N300. If OK, change N300

Master Reset (Purx), PSCLD pin 26 is "1" ( 3.16 V )
YES

NO

Rise up pin 26. If the logic evel is still "0", check soldered joints of N300. If OK, change N300.

Master clock input, ASIC (D151) pin 22 is 13 MHz, 1 Vpp, sine wave with 1 V DC level
YES

NO

Check components R150 and C153. If they are OK, check the VCXO block. One must remember that the control signal for the VCXO is taken from the baseband (see figure 6 )

Clock signal at the input of MCU (D150), pin 51 is 6.5 MHz square wave.
YES

NO

Check resistor R152. Check the soldered joints of ASIC. If OK, change ASIC

NO

MCU Reset input, pin 48 is "1"
YES

Rise up MCU pin 48. If the logic level is still "0", check the soldered joints of the ASIC. If OK, change ASIC.

Check that the following lines are correct. 1. Vpp line from J310 to FLASH (D400) pin 11 Normal fault information: MCU FLASH Vpp error 2. RXD line from J311 to MCU (D150) pin 2 Normal fault information: Serial data line failure 3. TXD line from J312 to MCU (D150) pin 1 Normal fault information: MCU doesn`t boot 4. SCK line from J313 to MCU (D150) pin 3. Check R315 also. Normal fault information: Serial clock line failure 5. WDDIS line from J314 to PSCLD (N300) pin 22 6. GND , J315 is connected to ground

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NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

In cases that fault information is a) MCU doesn`t boot b) Clock line serial failure the ASIC self test function can be used Reset is "0" 1. Connect a short circuit wire between Asic pin 137 and GND 2. Switch power on and measure the state of the MCU Reset line (pin 48) If the Reset line rises up to "1" state there are not short circuits There is a short circuit between the pins. Check circuits: D150, D151 D400, D403, D402.

Reset is "1" Check that there are not open pins in components: D150, D151, D400, D402

In case that fault information is: External RAM fault Check the pins of SRAM (D403) Check also the control lines of SRAM: WrX, RdX from MCU; RAMCS from ASIC

In case that fault information is: Algorithm file or alias ID don`t find, ID is unkwon etc. Check pins of the FLASH (D400) Check also the control lines of FLASH: WrX, RdX from MCU CSelX, PwrDown from ASIC

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PAMS Technical Documentation

NHE­8/9 Disassembly & Troubleshooting

Power doesn`t stay on or the phone is jammed
If a fault has come after the flash programming, there are most probably open pins in IC`s. The soldered joints of IC`s : D150 (MCU), D151 (ASIC), N300(PSCLD), D400 (FLASH), D403 (SRAM) is useful to check at first. Normally, the power switch off after 30 seconds, if the watchdog of the PSCLD can not be served by software. The power off function can be prevented by connecting a short circuit wire from the PSCLD pin 22 (WDDIS) to the ground. If the power switches off after 1..2 seconds, the pins of PSCLD and the PSCLD`s auxiliary components must be checked. If the phone is jammed, and no other reason has been found, the function of 32 kHz clock oscillator must be checked. This can be done by setting the phone to the ASIC self test mode. 1. Connect a short circuit wire between Asic pin 137 and GND. 2. Make a short circuit between the ASIC pins 78 and 79. 3. Switch power on. 4. Measure the signal by oscilloscope at pins 78, 79 (ASIC).

PSCLD pin 26, PurX (Master Reset)

ASIC pin 78 (MCUIRQ1X) and ASIC pin 79 (MCUIRQ0X)

30.5 us

1V

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NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

Power doesn`t stay on or the phone is jammed (In case that fault has come after the flash programming).

ATTENTION ! Do not forget to check needed PCB wires between the circuits.

Connect a short circuit wire from PSCLDs pin 22 to the ground. This make sure that power stays on during the measurements

Output voltages of PSCLD (N300) are 3.16 V (VL, VA, VSL). YES Master Reset, PSCLD pin 26 is "1" (3.16 V) YES Master clock input, ASIC (D151) pin 22, 13 MHz about 1 Vpp sine wave signal with 1 V DC level. YES NO MCU (D150) clock signal input, pin 51, 6.5 MHz square wave signal.

NO

Check the soldered joints of N300. If OK, change N300.

NO

Rise up pin 26. If the logic level is still "0", check soldered joints of N300. If OK, change N300. Check components R150 and C153. If they are OK, check the VCXO block. One must remember, that the control signal for the VCXO power supply is taken from baseband.

NO

Check resistor R152. Check that Master Reset input pin, ASIC pin 120 is "1". If it is "1" check soldered joints of ASIC. If OK, change ASIC.

YES NO MCU reset input, pin 48 is "1" YES Check that there are not open pins in components D150 (MCU), D151 (ASIC), D400 (FLASH), D403 (SRAM) OK Check the function of the 32 kHz oscillator Rise up pin 48. If the logic level is still "0", check the soldered joints of the ASIC. If OK, change ASIC.

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NHE­8/9 Disassembly & Troubleshooting

Display information: Contact service
This fault means that MCU is able to run and the watchdog of the PSCLD (N300) can be served. Thus PCLOCAL functions can be used and some information about the fault is possible to get. In principle, the fault for contact service information can be found around ASIC (D151), DSP (D152), RFI (N450), EEPROM (D402) or AUDIO CODEC (N200).
DSP (D152) pin 66 or testpoint J152) 39 MHz square wave
YES NO

NO

DSP pin 68: 13 MHz square wave
YES

NO

DSP pin 69 (XRES) is "1".
YES

Check the soldered joints of DSP (D152). If OK, change D152 Check R151 and soldered joints of ASIC (D151). If OK Change D151
NO

Check the soldered joints of ASIC (D151). If OK, change D151

DSP pin 20 (XF) or testpoint J153
250 ms Power On XF stays "1" after download Software download to external RAMs

Download is failed. Check soldered joints of ASIC (D151 and DSP (D152)

YES

Check soldered joints of DSP (D151) and external RAMs D405, D415 Check the soldered joints of ASIC (D151). If OK, change D151

RFI (N450) pin 51 (SYSRESX) is "1".
YES

NO

RFI (N450) pin 45: 13 MHz square wave
YES

NO

Check the soldered joints of ASIC (D151). If OK, change D151

Check soldered joints of RFI (N450), DSP (D152), ASIC (D151) Check soldered joints of EEPROM (D405) and connections to the MCU (D150). Check soldered joints of AUDIO CODEC (N200) and connections to the ASIC (D151).

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NHE­8/9 Disassembly & Troubleshooting

PAMS Technical Documentation

The phone doesn`t register to the network (no serv) or phone doesn`t make a call
If the phone doesn`t register to the network or the phone doesn`t make a call, the reason for this could be either the baseband or the RF part. The phone can be set to wanted mode by PCLocals software and try to find reason for fault. The control lines for RF are supplied both the ASIC (D151) and the RFI (N450). The ASIC handles digital control lines (between "0" = 0 V and "1" = 3.16 V) and the RFI handles analog control lines and proper input and output signals. The DSP uses its external flag outpin (XF pin 20) as an indicator of its operation state. During power up, DSP signals all completed functions by changing the state of the XF pin.

1 2 1 3 4 DSP pin 20 (XF) 5 2 3 4 5 6 7 6 7

XF (pin 20) is "1" after power on DSP code download starts DSP has performed self tests and initalization succesfully DSP has received SEARCH_LIST command from MCU ( DSP starts channel search) DSP starts PSW search ( Channel has been found) ( Rx and AGC are OK ) PSW has been found ( the synthesizer works OK) DSP has received synchroniza­ tion. ( AFC works OK)

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Phone doesn`t register to the network or phone doesn`t make a call
NO

NHE­8/9 Disassembly & Troubleshooting

RFI (N450) pins 9,10,11 DC level 4.5 V
YES NO

Check regulator N451. One must remember, that control signal for RFI regulator N451 pin 1 is taken from ASIC (D151) pin 130 and routed to the RFI regulator via PSCLD (N300) pins 24, 20 ( pins 17,13 ).

RFI (N450) pin 3 (REFOUT) DC level 2.5 V

Check components C452. If OK, Change RFI (N450)

YES

ASIC pin 33 (RxPwr) is "1" during the receive slot ASIC pin 34 (SynthPwr) is "1" during the receive slot ASIC pin 35 (SEna1X) is "0" during the receive slot ASIC pin 39 (SCLK) is "1" during the receive slot ASIC pin 38 (SDATA) is "1" during the receive slot
YES

Check the soldered joints of ASIC (D151) and the connections to the RF part

RFI pin 16 (TXCOUT) is "1" during the receive slot RFI pin 24 (PDATA0) is "1" during the receive slot RFI pin 24 (PDATA0) is "1" during the receive slot RFI pin 54 (RXINN): DC level 1.6 V during the receive slot RFI pin 55 (RXINP): DC level 1.6 V during the receive slot RFI pin 64 (AFC) : 1 V < DC level < 3 V
YES

NO

Use PCLocals functions to turn transmitter on

Check the soldered joints of RFI (N450) and the connections to the RF part

ASIC pin 31 (TXP) is "1" during the transmit slot ASIC pin 32 (TXPWR) is "1" during the transmit slot
YES
4.6 ms

NO

Check the soldered joints of ASIC(D151) and the connections to the RF part

YES

RFI pin 1 (TXQN) RFI pin 2 (TXQP) RFI pin 12 (TXIN) RFI pin 13 (TXIP)

1.1 V 2.6 V

NO

Check the soldered joints of RFI (N450) and the connections to the RF part

0.6 ms

CHECK RF PART

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PAMS Technical Documentation

SIM Card is out of order (insert SIM card or card rejected)
The hardware of the SIM interface from the ASIC (D151) to the SIM connector (X102) can be tested without SIM card. When the power is switched on and if the BSI line is grounded by resistor, all the used lines (VSIM, RST, CLK, DATA) rises up to "1" (5 V) four times. Thus the fault can be found without SIM card most of the cases.

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NHE­8/9 Disassembly & Troubleshooting

Display information: Insert SIM card or card rejected
YES

ASIC (D151) pin 25 (CARDDETX): DC level < 2 V, when 68k resistor is connected from BSI line (X100 pin 14) to the ground
YES

NO

Check resistors R311 and R312 Check system connector X100 pin 14 (BSI)

PSCLD (N300) pin 15 (SIMENA):pulses up to "1" (3 V), when the power is switched on
YES

NO

Check connection to the ASIC; pin 30 Check also soldered joints of ASIC (D151) and PSCLD (N300)

PSCLD (N300) pin 10 (SIM_I/O_CTRL): pulses up to "1" (3 V), when the power is switched on
YES

NO

Check connection to the ASIC; pin 26. Check also soldered joints of ASIC(D151) and PSCLD (N300)

SIM CONNECTOR (X102) pin C1 (VSIM) pulses up to "1" (5 V), when the power is switched on
YES

NO

Check connection to the PSCLD (N300) pin 41 and the soldered joints of PSCLD (N300)

SIM CONNECTOR (X102) pin C2 (SIMRST) pulses up to "1" (5 V), when the power is switched on
YES

NO

PSCLD (N300) pin 2 (SIMRST_S): pulses up to "1" (5 V), when the power is switched on
NO YES

PSCLD (N300) pin 9 (SIMRST_A) pulses up to "1" (3V), when the power is switched on
NO YES

Check R322

Check connection to the ASIC; pin 28 (SIMRESETX).Check also soldered joints of ASIC (D151) and PSCLD (N300)

Change N300

SIM CONNECTOR (X102) pin C3 (CLK): pulses up to "1" (5 V), when the power is switched on

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SIM CONNECTOR (X102) pin C3 (CLK): pulses up to "1" (5 V), when the power is switched on.
YES

NO

PSCLD (N300) pin 1 (SIMCLK_S): pulses up to "1" (5 V), when the power is switched on.
NO YES

PSCLD (N300) pin 8 (SIMCLK_A):pulses up to "1" (3 V), when the power is switched on.
NO YES

Check R324

Change N300 Check connection to the ASIC (D151), pin 29 (SIMCLK) Check also soldered joints of the ASIC (D151) and the PSCLD (N300)

SIM CONNECTOR (X102) pin C7 (DATA): pulses up to "1" (5 V), when the power is switched on.

PSCLD (N300) pin 3 (SIMDATA_S): pulses up to "1" (5 V), when the power is switched on.
NO YES

PSCLD (N300) pin 7 (SIMDATA_A): pulses up to "1" (3 V), when the power is switched on.
NO YES

Check R323

Change N300 Check connection to the ASIC (D151), pin 27 (SIMDATA) Check also soldered joints of the ASIC (D151) and the PSCLD (N300)

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NHE­8/9 Disassembly & Troubleshooting

Audio fault
In cases that audio routings are totally muted, a fault could be in serial bus. This serial bus is used for PSCLD (N300) and for Display driver also, so if the PSCLD and the display are OK, there are open pins in the AUDIO CODEC (N200) or the AUDIO CODEC is faulty. Serial bus faults can be found with PCLocals software (self test). Other possibilities are that PCM clock and sync lines are open. CODEC (N200), ASIC (D151) and DSP (D152) must be checked.
Keytones are missing and the earphone and the microphone are muted during a call.
YES NO

CODEC (N200) pins 18,41,42 (VA): 3.16 V
YES

Check the soldered joints of PSCLD (N300). If OK, change N300 CODEC (N200) pin 14 (CCLK): pulses up to "1", when the power is switched on. CODEC (N200) pin 15 (CSX): pulses down to "0", when the power is switched on. CODEC (N200) pin 16 (CDI): pulses up to "1", when the power is switched on.
YES NO

Check Audio interface with the PClocals software.
Result: OK

Result: Fault

NO

ASIC (D151) pin 40 (PCMDCLK): clock starts, when the power is switched on.
YES

Check the soldered joints of ASIC (D151). If OK, change D151.

Check the serial bus lines to the ASIC (D151)

Check UI board and connector X101 Keytones are OK. The earphone and the microphone are muted during a call.
YES

Change CODEC (N200)

ASIC (D151) pin 41 (PCMSCLK): clock starts, when the power is switched on.
YES

NO

Check the soldered joints of ASIC (D151). If OK, change D151. Check the soldered joints of ASIC (D151) and DSP (D152).

DSP (D152) pin 29 (FSR0): clock starts, when the power is switched on.
YES

NO

DSP (D152) pin 27 (CLKR0): clock starts, when the power is switched on.

NO

Check the soldered joints of ASIC (D151) and DSP (D152).

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PAMS Technical Documentation

Keytones are OK. Microphone (uplink) is OK. Earphone (downlink) is muted during a call.
YES

DSP (D152) pin 33 (CLKX0): clock starts, when the power is switched on.
YES

NO

Check the soldered joints of ASIC (D151) and DSP (152)

DSP (D152) pin 37 (FSX0): clock starts, when the power is switched on.
YES

NO

Check the soldered joints of ASIC (D151) and DSP (152)

CODEC (N200) pin 10 (DR): PCM signal during a call

NO

Check the soldered joints of CODEC (N200) and DSP (152)

Keytones are OK. Earphone (downlink) is OK. Microphone (uplink) is muted during a call.
YES NO

DSP (D152) pin 31 (DR0): PCM signal during a call
YES

Check the soldered joints of CODEC (N200) and DSP (152)

DC bias voltage (2.2 V) at MICP pin during a call

NO

Check the soldered joints of CODEC (N200) and bias voltage transistor V200, R201, R202, R210, R221.

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NHE­8/9 Disassembly & Troubleshooting

Charging fault
Two different kind of faults can be separated each other: 1. No information at all on the display, when a charger is connected. 2. Display information: Not charging. 1. In case that information on the display is not given, when a charger is connected, means that PSCLD (N300) , pin 14, can not change the level of the CHRG_IND line ( 0 ­> 1) or the input pin of the ASIC (D151) pin 126 is unconnected. 2. If the display information is: Not charging, the charger indication has been done, but the hardware control unit can not control the charging switch transistor V304.

Charger voltage (10 V) at emitter of V304
YES

NO

Check L107 and L108 and connector X100

Reference voltage 5.1 V at base of V302
YES

NO

Check resistors R301,R326 and zener V301

Charger indication voltage R302/R303 (1.8 V) at PSCLD (N300) pin 28.
YES

NO

Check resistors R302,R303

Charger indication voltage R302/R303 (1.8 V) at PSCLD pin 27.
YES

NO

Check soldered joints of PSCLD. If OK. change PSCLD (N300).

PSCLD pin 14 (CHRG_IND) is "1", when a charger is connected.
YES

NO

Check soldered joints of PSCLD. If OK. change PSCLD (N300). Check also connection to the ASIC (D151) pin 129

PSCLD pin 23 (CHRGSW) is "0", when a charger is connected.
YES

NO

Check soldered joints of PSCLD. If OK. change PSCLD (N300).

Check hardware control components V311,V302,V303,R305...

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Troubleshooting and Module Repairing at Service
The tests listed,can be executed on a complete phone either at module level or by way of PC­locals on a complete handset.

UIF­ connector
­ if module seems not to work, first check the condition of B­B­ connector

LCD
1. LCD does not work ­ check the voltages VL and V5, voltage difference (VL­V5) should be 7 to 9 volts ­ check the solderings of the TAB on to the PCB, i.e. H400 ­ check that correct values of resistors R416 and R419 are mounted ­ check the solderings of the periferal components arround the display 2. Missing rows in LCD ­ check if there are broken connections in the TAB. If yes, change the module. ­ check if there are breaks on LCD glass. If yes, change the module.

Microphone
1. Mic does not work ­ check board­to­board connectors ­ check microphone spring connection (eg. spring contact, dirt on springs). ­ change microphone if needed

Earpiece
1. Earpiece does not work ­ Send tone to earpiece ­ if no tone appears, check the spring contacts of earpiece (eg. spring contact to pads, dirt on springs) ­ change Earpiece if needed

Buzzer
1. Buzzer does not work ­ check the voltage VBatt ­ send tone to buzzer, connect PWM signal to BUZZER line ­ if no sound appears, check the spring connection to the buzzer ­ measure, that transistor V403 operates ­ change buzzer or transistors if needed

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NHE­8/9 Disassembly & Troubleshooting

Keyboard and display LEDs
1. Keyboard LEDs do not work ­ check the voltage VBatt ­ connect 'KEYLIGHT' line to logical HIGH and measure, that control transistors V404 and V405 operate ­ check the solder pads of LEDs ­ change LED or transistor if needed 2. Display LEDs do not work ­ check the voltage VBatt ­ connect 'LCDLIGHT' line to logical HIGH and measure, that control transistor V402 operate ­ check the solder pads of LEDs ­ change LED or transistor if needed

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