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Author Topic: WG 4900, cap blowing! (calling Ken Layton)  (Read 1927 times)

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ifkz

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WG 4900, cap blowing! (calling Ken Layton)
« 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  :)
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SirPeale

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #1 on: May 27, 2008, 07:23:28 am »
Meter the voltage at that cap leg, what is it?
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Ken Layton

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #2 on: May 27, 2008, 11:10:21 am »
Did you put it in with the correct polarity?
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qrz

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #3 on: May 27, 2008, 06:02:10 pm »
just for the fun of it , u may also wish to check d702 , r702   ;)


qrz 

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ifkz

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #4 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!
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qrz

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #5 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
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Ken Layton

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Re: WG 4900, cap blowing! (calling Ken Layton)
« Reply #6 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.
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