Wells U3000 - no power up

[jconstanza]

I have a WGM2730 that does not power on. Did a cap kit prior to it not turning on. Checked for broken traces, replaced Q101, also replaced U101. I tried hooking up a light bulb on pins 1 & 3 of CN104 and my bulb does not turn on so I guess I'm pretty sure the problem is in the power supply. Wells doesn't have a troubleshooting guide on their site. Any ideas/help gladly appreciated!

[qrz]

normally, a smps isn't terribly difficult to repair.
http://www.wellsgardner.com/pdf/Schematics/U3000_27_inch.pdf

check c117 , c107, c108, r102, r103, r108

also check snubber components  c106,r104, d107

check for loading on secondaries ...


qrz

[jconstanza]

Can those components possibly be bad even if they tested good or near good, I guess?

[qrz]

depending upon the testing method(s).... yes .

ESR ( effective series resistance) and DA (dielectric absorbtion) are two items most cap testers ignore.

in fact, my tester doesn't include DA... the next model up does .

i've had  old 'lytics test ok for value , but excessive esr.


there MUST be min of10v across c107 for the ic to operate.....

qrz

[jconstanza]

May I ask what tester you use?

[qrz]

sencore lc102...... i think  ?....will need to look       had it for many years of faithful service !

fyi, the majority of equipment i have is sencore.    and thankfully,  it all paid for itself !!

qrz