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Main => Monitor/Video Forum => Topic started by: ifkz on May 26, 2008, 11:48:41 pm

Title: WG 4900, cap blowing! (calling Ken Layton)
Post by: ifkz on May 26, 2008, 11:48:41 pm
Hi Ken,

I'm having trouble with my Wells Gardner 4900.

Symptoms:  Blowing cap c702, radial, 10uf@160V.  Brightness on monitor gradually increases as cap is dying.  No other problems.

Diagnosis so far:  Replaced c702 once, same results.  Tested r385 OK.  Tested r316 OK.

I'm no monitor tech, but I'm trying  :)
Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: SirPeale on May 27, 2008, 07:23:28 am
Meter the voltage at that cap leg, what is it?
Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: Ken Layton on May 27, 2008, 11:10:21 am
Did you put it in with the correct polarity?
Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: qrz on May 27, 2008, 06:02:10 pm
just for the fun of it , u may also wish to check d702 , r702   ;)


qrz 

Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: ifkz on May 28, 2008, 10:06:04 am
Yes the polarity of c702 is correct.  I even checked it against the other WG 4900 I have.

I'll have to have a friend help me out when it comes to metering the cap leg.  It always scares me to turn the monitor on while trying to meter a pad/leg!
Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: qrz on May 28, 2008, 06:07:51 pm
Quote from: ifkz on May 28, 2008, 10:06:04 am


I'll have to have a friend help me out when it comes to metering the cap leg.  It always scares me to turn the monitor on while trying to meter a pad/leg!

use one hand .  secure blk lead in chassis frame .  with STEADY hand , touch the rd lead to the test point .   ;D

electricity is not something to be feared .. but , one MUST RESPECT it  !!!!!! 

qrz
Title: Re: WG 4900, cap blowing! (calling Ken Layton)
Post by: Ken Layton on May 30, 2008, 12:27:25 pm
Quote from: qrz on May 27, 2008, 06:02:10 pm
just for the fun of it , u may also wish to check d702 , r702   ;)


qrz 



Yes, check for a shorted diode D702 or bad resistor R702. If those are ok the look for a shorted color driver transistor on the neck board.