You don’t need a multimeter to confirm some of these components need changing....

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I changed the components highlighted (Q4, Q5, Q6, D4, D4 & R5) in yellow except BR2 as I have tested it and it seems fine.

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BR Test using Multimeter in Diode testing mode gets a reading of between 0.5v to 0.7v for :
==> -ve MM lead on either the AC legs & +ve MM lead on the -ve DC leg of Bridge Rectifier BR2
==> +ve MM lead on either the AC legs & -ve MM lead on the +ve DC leg of Bridge Rectifier BR2

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All looking good and thought I was on for a quick easy fix but put it back in the game with the DMD unplugged and fuse F602 blows straight away.

FYI I have tested it in another machine so it's definitely the DMD Controller Board.

==> Is it possible that the Bridge Rectifier (BR2) can test ok but at higher voltage cause issues??

==> Are there any other components which could cause F602 to blow which I have not yet replaced??

I think I will be replacing BR2 just in case.

Thanks in advance for any suggestions

BR2 replaced and found C9 was shorted so replaced it... DMD working now like it did in 1994.

Thanks