Check the ground wiring
Solder the short wire to 25K. Connect the black side stick of tester to 25K. The mode of the tester is made resistance value measurement. Wind the short wire(about 2cm long) to the red side stick of tester. Touch the following check point with the red side stick, and confirm the connection. Touch the component lead directory.
Lead of emitter of TR1 ( 10E ) Lead of emitter of TR2 ( 10K ) 7th pin of IC socket ( 19K ) Minus lead of C1 ( 21M ) Lead of C2 ( 21K ) Ground lead of IC2 ( 21H ) Lead of C3 ( 21E ) Minus lead of C4 ( 21C ) All checking are OK, then disconnect the wire from 25K. Check +12V wiring Solder the short wire to 25I and connect the black side stick of the tester. Touch the following check piont with the red side stick. Lead of R6 ( 3L ) Lead of R4 ( 3D ) Lead of input of IC2 ( 22I ) Plus lead of C1 ( 22M ) Lead of C2 ( 22K ) All checking are OK then disconnect the wire from 25I. Check +5V wiring Insert the wire to the 14th(16E) pin of IC socket, and connect the black side stick of the tester. Touch the following check piont with the red side stick. Lead of output of IC2 ( 22G ) Lead of C3 ( 22E ) Plus lead of C4 ( 22C ) Check other wiring Check the following connection.| R4 | ( 6D ) | - | D3 | ( 5F ) |
| D3 | ( 6F ) | - | TR1 | ( 9F ) |
| TR1 | ( 8E ) | - | R3 | ( 8C ) |
| R3 | ( 12C ) | - | C6 | ( 12H ) |
| R3 | ( 12C ) | - | D2 | ( 15I ) |
| R3 | ( 12C ) | - | IC1 | ( 16G ) |
| D2 | ( 15F ) | - | R2 | ( 14H ) |
| R2 | ( 14E ) | - | IC1 | ( 16F ) |
| R2 | ( 14E ) | - | C5 | ( 18M ) |
| R6 | ( 6L ) | - | D4 | ( 5J ) |
| D4 | ( 6J ) | - | TR2 | ( 9J ) |
| TR2 | ( 8K ) | - | R5 | ( 8M ) |
| R5 | ( 12M ) | - | C5 | ( 17M ) |
| R5 | ( 12M ) | - | D1 | ( 15N ) |
| R5 | ( 12M ) | - | IC1 | ( 16K ) |
| D1 | ( 15K ) | - | R1 | ( 14M ) |
| R1 | ( 14J ) | - | IC1 | ( 16J ) |
| R1 | ( 14J ) | - | C6 | ( 12I ) |
Check the shortage of the power line The mode of the tester is made low resistance value measurement. Connect the red side stick to 25K(ground) and connect the black side stick to 25I(+12V).It is not misconnection. Because, in case of analogue type tester the plus voltage of inside-battery appears to the black side stick, and minus voltage appears to the red side stick.
Check that resistance is not almost zero-ohm. In my case, there is about 600-ohm. If I connect conversely, there is 40-ohm. In this case the voltage is opposite then there is no problem.