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wells gardner pd279410 rev 7.3 chassis
techoff2:
Those resistance readings were done with t501 removed from the cct board so c507 would have no influence.
lilshawn:
okay, so was t501 in or out when the circuit breaker you have powering it faults? you didn't mention removing it at all, just that you tested it.
have you tested the rectifier?
easy peasy rectifier test... remove rectifier, place meter in diode test mode. place black negative lead on the positive power leg of the diode pack... red lead to each of the AC terminals. each AC leg should show 0.5 diode drop. place positive meter lead on the negative lead of the rectifier.... same thing... negative lead to each AC leg of the rectifier. each should show 0.5 diode drop. any of the 4 tests shows 0.000 (infinity if analog), a diode is shorted. if the meter shows OL (or 0 if analog) diode is open. if they all show 0.5 or thereabouts, diodes are fine. if diode measures out higher than about 0.6 or lower than 0.4 it's suspect and could be leaky or on it's way to failing.
transformer pin readings (this is for a TPW-E42901 transformer taken from a D9500 (basically a 19" version of the 25" 9400 but the part number on it matches the one listed in the 9400 schematic and not the one in the D9500 ??? ) and taken with a fluke 87III in 4 1/2 digit mode and lead resistance nulled out.)
Primary side
1-3 - 0.44 ohms
5-6 - 0.04 ohms
no pins from 1-3 have any connection to pins 10-18
10-11 - 0.64 ohms
10-12 - 0.61 ohms
13-15 - 0.34 ohms
16-17 - 0.03 ohms
16-18 - 0.06 ohms
16-15 - 0.07
so it's possible the transformer is shorted internally, but not enough to catastrophically fail, but enough to trip a circuit breaker before it does.
maybe try and apply like 12 or 24vdc (even 42v if you have access) to pin 1 and measure for voltage leaking through to pins 5/6 and the other side through pins 10-18 to be extra sure.
if it is shorted internally, i suppose i got this one (if it's the same). i live in canada so it may be prohibitively expensive to ship depending where you are.
techoff2:
I removed t501 to test its resistances and then put it back in to carry out the testing that you recommended.
The bridge is ok.
On the transformer that you have do you have any resistance readings from pin 15 to pin 6.
I have a short about 0.1 ohm.
The schematic that I have shows no electrical connection from pin 6 other than to pin 5.
pin 5 to 6 is around 1.5k ohms
lilshawn:
no pins from 1/3 have any connection to the pins 10-18 or the 5/6
essentially 3 separate coils of wires.
1 and 3 is the primary high voltage coil.
5 and 6 is a feedback/power supply for the SMPS chip
10 to 18 is secondary side providing all the different voltages.
techoff2:
Finally finished this beast.
The transformer was shorted from pin 6 to pin 15 causing an AC short to ground and blowing the house cct breaker.
Also make sure you use the correct UC3842b SMPS ic as other variants don't work in this chassis.