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31" GE Fails to Turn on: 31GT660

 
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BobGeorge
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PostPosted: Mon Nov 14, 2005 10:08 am    Post subject: 31" GE Fails to Turn on: 31GT660 Reply with quote

Was working fine, began not turning on at times (remote or manual no longer turns on). Control Ckt V Reg? Grounds? ...what have you found?
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PostPosted: Mon Nov 14, 2005 4:01 pm    Post subject: Reply with quote

TCE CTC 187

NO HORIZONTAL SWEEP (CTC 187CL)
C4404 has probably blown up
Caused by an open C4403



BUZZING SOUND: See following problem as DEAD.



DEAD with F4001 blown and either a buzzing sound prior to failure or a hole burned in the bottom of the board under C4007 when received.

Possible problem: Highly repetitive problem with a defective C4007 (190560)



Dead, possibly with a slight squealing sound

Found Q4401 shorted and no reason readily apparent. If IHVT is removed and “rang”, it appears to check ok. The problem is though, that the IHVT is breaking down and arcing after replacement of the HOT.



Dead with H.O. Transistor shorted (27” or greater screen sizes generally)

After replacing the output transistor, no other problem could be found except that the heat sink is running too hot. It should run warm, but not to the point where it would burn you. This problem causes the H.O. Transistor base signal to be apx. 16 volts p-p instead of the normal 12 volts p-p. If you find this 16volt signal, replace the Horizontal Driver Transformer (T4301), part number 215541 for the drawing number 30949060.
If during your testing you find that the Horizontal Driver Transistor base signal is too great, replace the clamping diode CR4303. This can be the cause instead of the driver transformer, so this driver base signal has to be checked also.
Also replace C4302 #190552 and C4309 #190548. Clean well under where these capacitors were mounted.
Note: We have had two instances where none of the above reduced the 16v p-p to the factory required 12v p-p.



DEAD:
CR4106 shorted, F4001 open and U4101 not functioning at all

CTC187BD2
U4101 215530
CR4106 164589
F4001 GMA 5


CTC187CL2
U4101 223948
CR4106 164589
F4001 GMA 5



DEAD with pincushion problem prior to set going dead

C4407 open, CR4106 and CR4403 shorted, F4001 open and U4101
not functioning at all.

CTC187BJ
U4101 215530
CR4403 & CR4106 164589
C4407 214754
Q7403 is 215495
Q7404 is 215496
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