Today i have 2 Dolby Model 740 Spectral Processors that have gone down for some reason.

One is usually in the rack and the other is a spare i picked up as these are very rare.  The one i was using failed so i switched in the spare.  That one promptly died too!  I actually saw and smelled a poof of smoke when the second one died…

 

I opened it up and found that one of the output driver chips had smoked.  It’s really odd that  both failed and the same chips failed in both.  End of life exactly the same time…

The repair was pretty easy, it’s just hard to remove chips that are mounted on the board.  I resorted to cutting the pins and removing each one individually.  These devices are very well laid out inside and easy to work on.  The front slides out and the whole board is easy to get to.