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PSU clicking issue (Wang)

Could well be a shorted diode on the board.

It's not foolproof, but at least you can determine the +5 pin by measuring the continuity between the lines on the edge connector and the Vcc pin on any 7400-series TTL IC on the board. If you can find RS232 level shifters, such as an MC1488, you can also locate the +12 and -12 lines, based on the IC pinout.

If you've got 16K DRAMs on the board (i.e. 4116, 2117), that will allow you to trace -5, +12 and +12 lines.
 
Do you know any good friendly TV repair guy's, Might be worth having a word with them, They could probably run through that PSU pretty quick for a pint or two, Connecting the edge connector to a "Modern(ish)" PSU may still yield the same problem if the fault is elsewhere in the machine, It's a long shot but have you tried probing the wires to see if you're getting anything ?, From the Pic of the PSU i can see red / black / white and what looks like yellow and blue wires is that correct ?
 
Thanks for that guys! There's a few ICs on the board, none of them are RAM chips; I will look for the pinouts of the chips that are there -
Malc; I don't know anyone who repairs TVs - but I did probe the wires as you suggested... interestingly, there is a contant output of voltage, i.e it's not dropping to 0 with the ticking noises.. It seems to be providing proper voltage too.. for the most part. The bottom part of the edge connector (closest the the wires) provides 3.5V (the red wires provide this source of power), then about 75% of the way through the bottom, the blue wire provides between 11.4 and 11.5 (fluctuating) V. The last pin which is connected to the yellow cable provides -12.1V.

The top of the edge connector is not connected to anything (at least that's what the traces under the board show) and thus don't register anything on the multimeter; The white wire to the side of the edge connector goes into the first pin of the top of the edge connector, but doesn't provide anything.
The second white wire goes into the first pin of the bottom of the edge connector, and provides exactly 2V....
I am thinking the 3.5V should be 5, but perhaps it won't do that if it's not under load? In which case, possibly the main board is at fault? It doesn't visually show any damage on first, second or third glance :S
 
Are you measuring correctly the blue and yellow wires, usually the yellow = +12v and blue = -12v but some manufactures do like to play differently, Looks like a problem on the 5v line red = +5v and white = -5v, Have you changed all the caps ?, You could trace through the 5v line and look for possibly a bad cap / diode / voltage reg etc.
 
Have you checked all of the diodes on the PSU board--in particular, the TO-220 packaged ones that often are 3-lead devices with two diodes sharing a common lead. It's not unknown for one of these to fail short.
 
Hi Chuck,
I didn't test these.. I will do this as soon as I get home!
Just for information, I drew up a really rough schematic earlier of what the 5v area looks like - just the bit where the cables for the edge connectors are soldered.

 
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