ELECTRONICS TROUBLESHOOTING

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Muti-vibrator Troubleshooting

 

The LEDs do not display the actual repetition rate of the multi-vibrator. The scope displays do. Resisitance is given in ohms(3.5k = 3500 ohms) and capacitance in farads (4.7u = 4.7 micro-farads).


For the Baseline, Fault 1 and Fault 2 recording below:
Frame 1 ) BE1 signal (offset -1 volt to eliminate signal overlap).
Frame 2 ) BE1 and CE1 signal.
Frame 3 ) BE1, CE1, and CE2 signal.


Base Line Recording
Sensitivity: Vert: = 2volt/cm ; Horiz: 100 msec /cm

Determine which faulty component listed below is the cause of Fault 1 and which faulty component is the cause of Fault 2.
 Select From: 1) R2 resistance increased. 2) R3 resistance increased. 3) C1 capacitance decreased. 4) C2 capacitance decreased. 5) T1 open collector to Emitter.)  6) T2 open collector to Emitter. 

 


Fault 1 Recording
Sensitivity: Vert: = 2volt/cm ; Horiz: 100 msec /cm

 

 


Fault 2 Recording
Sensitivity: Vert: = 2volt/cm ; Horiz: 100 msec /cm

 

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Fault 1 Answer

C2 capacitance decreased.

 

Fault 2 Answer Below

 

 

Fault 2 Answer Below

 

 

Fault 2 Answer

R2 resistance increased