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Main => Monitor/Video Forum => Topic started by: Shaker73 on May 11, 2015, 03:00:08 pm

Title: Wells wmg2574 shuts down after it is on.
Post by: Shaker73 on May 11, 2015, 03:00:08 pm

I have a wells wgm2574 monitor that shuts down after it is on for about 5 minutes. Turn it off and back on and it comes right back on. Any suggestions?

Title: Re: Wells wmg2574 shuts down after it is on.
Post by: epicfatigue on May 12, 2015, 05:59:35 am

check the b+  with an analogue multimeter and see if you get a spike leading up and to shudown also record the voltage.

Title: Re: Wells wmg2574 shuts down after it is on.
Post by: qrz on May 13, 2015, 07:48:35 pm

IF this is the correct schematic :
https://www.wellsgardner.com/pdf/Schematics/K7400_25_inch.pdf (https://www.wellsgardner.com/pdf/Schematics/K7400_25_inch.pdf)

check R104 (10K/7W)   on SMPS primary.   must be <12K

R120 on the secondary side is also tolerance sensitive
68K/2W    use a 3 Watt when replacing

Title: Re: Wells wmg2574 shuts down after it is on.
Post by: Shaker73 on May 21, 2015, 05:48:00 pm

R104 is at 9.73K and R120 is at 67.8K. B+ went up to 300volts when it shutdown. It stayed at 160v after that.

Title: Re: Wells wmg2574 shuts down after it is on.
Post by: qrz on May 23, 2015, 08:34:42 pm

ok.
the resistors are within 3% of spec .
may be an issue in the feedback circuitry.

check the following diodes
D105, 107 - 113, 117
also check R108, C126.

although not a common failure, check C105.

replace C713 and C730
SHOULD have gone into shutdown before ever reaching 300v !

while in it , suggest replacing the following capacitors as well

C107,115,126,310,502,610,613,615,706,709,716,805 and 806