28 May
2008
28 May
'08
11:11 a.m.
Rik wrote:
I think you mean the small transformer with 6 wires
attached,
this transformer has 2 * 9VAC outputs and one AC-line input
(230 or 110V depends on region) This transformer is the
supply for the regulator IC's in the PSU the regulators are
places on two small PCB's, on the large PCB there is a
rectifier (Greatz) witch you have to check.
If thats alright you have a reasonable change the PSU works
after replacing the transformer with a similar type 2 * 9VAC 3 to 5VA.
Hi Rik,
There are 3 transformers on the board:
UNNAMED is the largest transformer, and outputs 9VAC for the monitor (blue
wires), and A.N. Other voltage which goes into 1 side of the second
rectifier (red wires)
T1 is the mid-sized one, and is the one that's blown on my PSU. It has 12
pins out in total, 6 per side.
T3 is the small one (although it's tall on the 240v board, and squat on the
110v board) with 6 wires (3 per side).
I guess UNNAMED may be T2, but I can't see the label.
T1 & unnamed on the 240v board are the same size as their contemporaries on
the 110v board. T3 is half the size on the 110v board.
I guess I should provide a bit more info too.... I know the UNNAMED
transformer is OK, as it's outputing volts to both the monitor & the board.
T3 also operational.
T1's primary (mains side) windings are passing current, but there's nothing
whatsoever on the secondary side. My guess, however, is that the fault is in
the T1 primary coil; otherwise it wouldn't have made such a nasty crack
noise, and vapourised the fuse.
I can't believe that T1 is the same between both boards, as one side of it
is connected to the mains. That said, it looks like it's only getting a
subset of the mains power - the top of each peak has already been rectified
off, if my oscilloscope is to be believed.
I'm not sure about the rectifier; I've swapped out one of them with its 110v
counterpart (it's all on the LV side, so I'm guessing it's an identical
part), but as it's only getting power to one side, there's basically bog all
going into the 12v daughter board.
Many thanks for your assistance,
Ade.
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