Harman Kardon HK3470. Would not come out of standby and only had the loudspeaker 1,2 LEDs lit. This was an annoying job. I thought it was going to be a nice straight forward repair, all the usual dry joints etc. So with the main board out, yes, lots of dry joints around the regulators and standby transformer. All attended to and the board replaced. But still there was something strange going on with the two separate 5VDC lines. One comes from the standby supply, the other comes from a winding on the main transformer. Lots of ripple on the 5V-U. One faulty LM7805 and decoupling capacitors. The thing is, the service manual is incorrect with the two 5V lines coming from incorrectly numbered components, which lead me on a dance. Then found that the track on the main board connecting 0V from the 5V regulator had a crack and was intermittent. When you test, you must make sure all the screws are fitted securing the main board to chassis, otherwise 0V grounds are not linked and that causes all kinds of odd things to happen.
