Is my WPC transformer fubar?

[Wizcat]

My BSD has been down, for a little while now. I'd put off looking at it because I was sure my multimeter was broken and giving me duff readings. So I borrowed a Fluke from @replicas, and now I'm pretty sure I have something very very wrong

All the test points on the driver board are out:
TP7, should be 20VDC, I see 7V
TP6, should be 50VDC, I see 7V

(Slightly weird maybe, but the 5VDC is pretty spot on, the game boots perfectly and I dare say I think it plays ok too apart from the 20VDC for the magnet motor being only 7V and so refusing to move)

So anyway, I went further back, to the incoming fuses F111 should be 16VAC I think. But I see 6VAC
F112 I think should be 16VAC too? But I see 27VAC?

So then I went even further back, and (after some effort) yanked out the transformer output cable. First thing I noticed was that it looked like this:



And the voltages I get (all AC) are as follows. Anyone know how badly wrong this is?

(Assume I'm holding the connector upside down in that photo, then I see)
row 1 = RED , RED , WHITE/RED
= 10 , 4 , 11

row 2 = WHITE/RED , WHITE , GREY
= 3.5, 41, 23

row 3 = BLK/YEL , WHITE , GREY
= 40 , 36, 10

row 4 = BLK/YEL , WHT/GREEN , GREY
= 10 , 8 , 4

row 5 = WHT/GREEN , BLU/WHT , BLU/WHT
= 3, 13 , 6

I need a new transformer... right?

 

[pinballmania]

Where is your black meter lead at this point? It shouldn't be on ground. I suspect it is. Ac voltages should be measured across the ac pair. E.g. Red to red/white.

 

[pinballmania]

In 15 years I've never had to replace a wpc transformer.

 

[Wizcat]

Ahh, yes - I was just reading about how I'm doing it wrong from this article
http://www.iobium.com/wpc_transformers.htm

So far I've tested

pins 1/2 = 10v
3/4 = 16v (spec says 16)
5/8 = 88v (spec says 80)
6/9 = 20v (spec says 18)
9/12 = 20v (spec says 18)
6/12 = 39 (spec says 36)
7/10 = 56 (spec says 51)
11/13 = 11.5 (spec says 9.8)

So yes, I think the transformer is ok ... Is it likely that both bridge rectifiers are gone? How do I test input AC there?

 

[pinballmania]

Have you tested the fuses? It's hard to measure on the bridges rectifiers I situ because the contacts are hidden. But you have one leg which is offset from the rest. This is your positive dc. Diagonally opposite is ground. The remaining two are the AC input.

 

[pinballmania]

When you measure your dc voltages where is your black lead? If using the earth braid check that it is actually connected to earth. Use meters continuity test to see that it is connected to the earth pin of the mains plug.