PT-TW342, PT-TX402, PT-TX312 (serv.man2) - Panasonic Projector Service Manual (repair manual). Page 4

1.1.  General Guidelines
  - For continued safety, no modification of any circuit must be attempted.
  - Unplug the power cord from the power outlet before disassembling this projector.
  - Use correctly the supplied power cord and must ground it. 
  - It is advisable to use an isolation transformer in the AC power line before the service. 
  -  Be careful not to touch the rotation part (cooling fan, etc.) of this projector when you service with the upper case 

removed and the power supply turned ON.

  -  Observe the original lead dress during the service. If a short circuit is found, replace all the parts overheated or 

damaged by the short circuit. 

  -  After the service, all the protective devices such as insulation barriers, insulation papers, shields and isolation 

R-C combinations must be properly installed. 

  - After the service, check the leakage current to prevent the customer from getting an electric shock. 

1.2.  Leakage Current Check 
  1.   Prepare the measuring circuit as shown in Fig. 1. 
      Be sure to use a voltmeter having the performance described in Table 1. 
  2. Assemble the circuit as shown in Fig. 2. Plug the power cord in a power outlet. 
  3. Connect M1 to T1 according to Fig. 2 and measure the voltage. 
  4. Change the connection of M1 from T1 to T2 and measure the voltage again. 
  5.  The voltmeter must read 0.375 V or lower in both of step 3 and 4. This means that the current must be 0.75mA 

or less. 

  6.  If the reading is out of the above standard, the projector must be repaired and rechecked before returning to the 

customer because of a possibility of an electric shock. 

1.3.  UV Precaution and UHP Lamp Precautions
  - Be sure to unplug the power cord from the power outlet when replacing the lamp. 
  -  Because the lamp reaches a very high temperature during its operation, wait until it cools completely when 

replacing the Lamp Unit. 

  - The lamp emits small amounts of UV-radiation, avoid direct-eye contact with the light. 
  - The lamp unit has high internal pressure. If improperly handled, explosion might result. 
  - Because the high pressure lamp involves a risk of failure, never touch the lamp wire lead during the service. 

Fig. 1

Fig. 2

Table. 2

Weighted leak = Vb/500A

Accuracy:
Input resistance:
Input capacity:
Frequency scope:

To power outlet

Insulation transformer

Connect

Projector

Measure 
circuit 
(Fig. 1)

Fig. 2

Table. 2

To T1 
or T2 
in Fig. 2

15HZ to 1MHZ

Voltmeter
(rms reading)

Performance