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Main => Monitor/Video Forum => Topic started by: Doughbroz on December 18, 2007, 02:20:05 pm

Title: odd WG7000 startup problem
Post by: Doughbroz on December 18, 2007, 02:20:05 pm

Odd to me, anyway, never saw this before.  On a cold startup, absolutely nothing.  No pic, no crackle, no glow in neck.  In this condition, I have 60VAC on both ends of the fuse.  The test pin next to the RGB inputs is .23 volts.  In the corner of the chassis next to the transformer there are two large resistors connected end to end, mounted vertically, with the other ends going into the chassis.  Voltage at the connection point between the two is 126 volts.  It will stay in this condition until power is turned off and back on, then the monitor immediately fires up and works normally until the next cold start.  As long as it's warm, it will start up every time.  When working, the aforementioned voltages are 12 volts and 90 volts.  It's not a bad connection because I can prod, poke, and beat on the chassis with no effect, and all solder joints look perfect.  Any ideas before I waste a cap kit,  or is that the first thing to try.  Thanks

Title: Re: odd WG7000 startup problem
Post by: Ken Layton on December 18, 2007, 06:17:45 pm

If it hasn't had a capkit then that's the first thing to do. Bad caps (off value or open circuit or 'leaky') can cause intermittent startup problems or even cause heat related problems.

Title: Re: odd WG7000 startup problem
Post by: qrz on December 18, 2007, 06:30:55 pm

there is a 47uF @63 volt cap in the smps that will cause it to have start up issues.
the cap filters the b+ to the pwm drive ic .

qrz

Title: Re: odd WG7000 startup problem
Post by: Ken Layton on December 18, 2007, 06:52:42 pm

Um.... the K7000 does not have a switch mode power supply.

Title: Re: odd WG7000 startup problem
Post by: sarge on December 18, 2007, 06:56:29 pm

I've always had luck changing C57 (47@160) to cure startup and shutdown problems with this monitor.

Title: Re: odd WG7000 startup problem
Post by: Doughbroz on December 18, 2007, 09:19:15 pm

Thanks guys, cap kit it is.

Title: Re: odd WG7000 startup problem
Post by: qrz on December 18, 2007, 09:54:01 pm

um..., ur right ken  :-[
thats what i get for jumpin' the gun.....must be gettin' senile ....?   :cry:

 if faulty, c23  (47uF@25v)  would cause the horiz osc to be unstable......
the 47uF @160v ( c57) is vreg filtering . if faulty, the regulated voltage will be unstable and may
cause some interesting symptoms in several stages.......

 here's the print :

  www.arcadeworldllc.com/images/Scans/Monitor%20Schematics/Wells_Gardner_K7000_Service_Manual.pdf

qrz